Friday, December 26, 2008

Laptop Shipments Finally Beat Desktops

As reported in this December 23rd piece by Information Week, the new laptop player hiding in these numbers is the NetBook. A netbook is defined as an ultralight, ultraportable PC with screen sizes 10 inches or less. With no CD/DVD drive and limited storage, prices can be as low as $300. Thanks but, no thanks! just give an iPhone.

What's Up (and Down) for 2009

My Aussie colleague, Steve 'Jenks' Jenkin, just pointed me at Robert X. Cringely's (real name: Mark ... Well, who cares? Besides, I like the 'X' factor) prognostications for 2009. Even though he's basically a journalist (a very plugged-in journo, btw), you gotta respect a guy who also reviews his previously wrong predictions.
"Final (2008) score: 4 right and 11 wrong. ... Obviously I have to start making vaguer predictions ..." :-)

Despite this self-flagellation, he's generally had some pretty good insights prior to 2008 and you can't win 'em all, all the time. Here are some of his darts-in-the-wall for 2009:
  • "The good news is that most recessions mean new IT platforms."
  • "The next Yahoo CEO will dismember the company and sell it piecemeal."
  • "Microsoft and Google will peak in 2009 ... Steve Ballmer is toast." [ Jenks claims 2010 for the M$ demise.---njg] (Like Humpty-Dumpty, The Goog) "... is too fat and happy."
  • "If Microsoft and Google are down then what's up? Apple!"

Please standby. ...

Friday, December 19, 2008

Guerrilla Manifesto Online Updated

Those of you who own a copy of Guerrilla Capacity Planning, know about the little manual included in the back jacket (my editor's idea, btw). The intent is to use it as a weapon of mass instruction in your Tiger Team meetings or whatever. As my Aussie colleague, Steve Jenkin, pointed out to me at the time I was writing that book, those of you in the trenches often run into resistance when trying to propose some capacity or performance approach because you lack the authority; even if your argument is an excellent one.

The role of the Guerrilla Manifesto is to provide you with more authoritative support via the various mantras listed there. Hardcopy is good, but online is better; especially for use with your mobile phone. The most recent updates are now available and have been indexed for easier reference. Let me know how this works for you.

CMG 2008 Boot Camp Sessions

Those of you who attended my Capacity Planning Boot Camp sessions at CMG 2008, may have noticed that something got lost in the translation between my original notes and what landed on your CMG CD. The corrected slides, including updated hyperlinks, are now available as PDFs from my CMG Materials page.

If you didn't attend CMG 2008, but you'd like to know more about capacity management techniques, consider coming to my 2-day Guerrilla Boot Camp class in 2009.

Tuesday, December 16, 2008

Gunther Receives A.A. Michelson Award

At the annual CMG International Conference in Las Vegas last week, Dr. Neil Gunther was the recipient of the prestigious A.A. Michelson Award; the industry's highest honor for computer performance analysis and capacity planning. As he said in his acceptance speech, it was the fulfillment of a dream he had entertained at his first CMG Conference in 1993.

Tuesday, December 2, 2008

Linux Meets Zipf's Law

It's amazing how power laws seem to be seen in everything these days:

A team of researchers from ETH Zürich (Einstein's alma mater) in Switzerland used four decades of data detailing the evolution of open source software applications created for a Linux operating system to confirm the adherence to Zipf's law. The team studied Debian Linux, as it is continuously being developed by more than 1,000 volunteers from around the world. Beginning with 474 packages in 1996, Debian has expanded to include more than 18,000 packages today. The packages form an intricate network, with some packages having greater connectivity than others, as defined by how many other packages depend on a given package.

It's also amazing what passes for physics these days:

T. Maillart.; D. Sornette; S. Spaeth, and G. von Krogh. “Empircal Tests of Zipf’s Law Mechanism in Open Source Linux Distribution.” Physical Review Letters 101 218701 (2008).

Wednesday, November 26, 2008

Is the Internet Green?

Research at the University of Melbourne in Australia, presented to the Symposium on Sustainability of the Internet and ICT, claims that a surge in energy consumption caused by the increased adoption of broadband will continue to slow the Internet. The study is the first to model Internet power consumption due to services like video on demand (VOD) and will enable MU researchers to identify the major contributors to Internet power consumption as the adoption of broadband services grows in the coming years.

Monday, November 24, 2008

Worldwide Supercomputer Ratings

Interesting visualization of worldwide supercomputer performance. These Flash bubble-charts seem to be de rigueur for the NYT now. Bubble diameters are proportional to their TFLOPS rating and the location of each bubble cluster is topologically correct with respect to geographical location, but not by Euclidean distance; which is probably why it wasn't superimposed on a map.

The breakdown of these top-100 machines by processor family (not shown there) looks like this:

  1. Intel: 75.6%
  2. IBM: 12%
  3. AMD: 12%
  4. NEC: 0.2%
  5. SPARC: 0.2%
However, the number 1 machine (at 1.1 petaFLOPs) is based on the IBM Cell processor.

Wednesday, November 19, 2008

What the Harmonic Mean Means

As I discuss in Chapter 1 of The Practical Performance Analyst, time is the fundamental performance metric. Computer system performance metrics are therefore either direct measures of time, e.g, seconds, hours, minutes, or they are rates. All rate metrics have their units of time in the denominator, e.g., GB/s, MIPS, TPS, IOPS.

A conceptual difficulty can arise when we try to summarize a set of performance numbers as a single number; especially if they're rates.

Thursday, October 23, 2008

Andy Bechtolsheim Leaves Sun

Aiming at the 10 Gb ethernet market, Andy Bechtolsheim is moving on to become chairman of a new company, Arista Networks, which he also co-founded. That leaves only Scott McNealy as one of the original founders now remaining at Sun.

Wednesday, October 15, 2008

Scalability Workshop (Melbourne, Australia)

Just a reminder about the 2-day workshop being run by NICTA---National Institute for Information and Communications Technology Australia.

Tuesday, October 14, 2008

Every Cloud ...

Guerrilla Graduate Paul P., pointed out recently that Wall Street's losses may be IT's gain. This is consistent with an earlier Slashdot piece, which stated that the data center technology owned by bankrupt Wall St. banks provides a significant chunk of the asset valuation assessed by buyers.

Perceiving Patterns in Performance Data

All meaning has a pattern, but not all patterns have a meaning. New research indicates that if a person is not in control of given situation, they are more likely to see patterns where none exist, see illusions and believe in conspiracy theories. In the context of computer performance analysis, the same conclusion might apply when you are looking at data collected from a system that you don't understand.

Put differently, the less you know about the system, the more inclined you are to see patterns that aren't there or that aren't meaningful. This is also one of the potential pitfalls of relying on sophisticated data-visualization tools. The more sophisticated the tools, the more likely you are to be seduced into believing that any observed patterns are meaningful. As I've said elsewhere ...

The research experiments used very grainy pictures, some of which had embedded images and others which did not.

Friday, October 10, 2008

All Aboard the Pain Train: The Valley View

Eric Eldon, at, obtained a copy of the recent presentation given by Sequoia Capital, entitled "RIP Good Times" and presents their VC perspective on how the current economic crunch came about, how it will impact the high-tech sector, and what can be done in response. It ain't pretty but Sequoia should know since they are a major Si Valley VC company that has provided financial backing for local emblems like Apple, Cisco, Oracle, and Yahoo.

Naturally, they commence by pointing fingers at Wall St. (hint, hint, hint) and the lack of regulatory oversight (although, I think Sequoia is probably more concerned about potential new regulations). Paraphrasing some of their points that are relevant to the IT sector:

  • In terms of the standard econo-metrics, this crisis appears to be unique and therefore recovery may take much longer.
  • If you want to see the future, look at Japan's recent economic history.
  • Manage cash expenditures and focus on quality. [That last one's a doozy. QUALITY ... What's that!?--ed.]
  • Advertising markets are cracking. Retail and e-commerce are deteriorating. Mobile is not immune.
  • IT spending is now being scrutinized more than at any time since the 2003-2007 period. [??? But 2007 was only last year.--ed.]
  • These concerns have triggered a sudden and unexpected drop in business activity.

Although these comments are based on US market data, we do live in a global village . Here is the Sequoia presentation.

Thursday, September 25, 2008

GCaP Training: A Rock-solid Investment

Looking for a rock-solid investment during the financial meltdown? Seats are still available for the next Guerrilla Capacity Planning class, which will be held in November at our Larkspur Landing location.

Entrance Larkspur Landing hotel Pleasanton California
Click on the image for details.

For those of you coming from international locations, here is a table of current exchange rates. We look forward to seeing all of you in November!

Thursday, September 18, 2008

My CMG 2008 Presentations

  1. Sunday Workshop: "How High Will It Fly? Predicting Scalability"
    Session 184, Sunday 8:30 AM - Noon
    Room: Champagne 3/4

Wednesday, September 10, 2008

Logjam at the London Stock Exchange

Guerrilla Graduate Paul P., sent me this WSJ bit on the recent 7-hour outage at the LSE, with the remark: "This kind of outage is a big, big deal in my world." This is the second technical failure at the LSE in 2008. The article points at capacity problems:
"Traders experienced problems connecting to TradElect, a 15-month-old proprietary LSE platform developed with Microsoft Corp. technology that the LSE has touted as allowing it to expand and speed up its capacity for trades."

"By early afternoon, the LSE was informally telling customers that its system would be back online. That appears to have created a logjam as customers tried to reconnect at the same time."

This is almost a replica of a problem described by my colleague Steve Jenkin in our 2006 CMG-Australia paper:
"That load was completely disabled to improve system throughput for the most interesting capacity planning period on the busiest day. This scheduling was mandated by the Secure Hosting Facility after a software fault caused a flood of more than 6,000 emails to be issued after a multi-day stoppage. Such an email flood, containing several days of traffic in 10 minutes, brought the facility mail system to its knees ..."

Some things ...

Friday, September 5, 2008

Google Chrome: Does It Shine?

The envelope please!

This early review indicates the luster is already off Chrome, due to some serious performance issues related to the Adobe Flash plug-in being a CPU hog. Unlike FireFox, there's no workaround.

Thursday, September 4, 2008

Best Practices

The Guerrilla Manual advises: Best practices are an admission of failure (last item in Section 1). As Wittgenstein said: "Just because we all agree on something, doesn't make it right."

Guerrilla graduate Scott J., sent me the following cartoon by Scott Adams, which offers a Dilbert profundity on the same topic.

For me, the punch line IS the 2nd frame. You may need to click on the strip to see the Dilbert punch line in the 3rd frame.

Wednesday, September 3, 2008

Scalability Workshop in Melbourne, Australia

NICTA is offering a 2-day workshop entitled:
Application Scalability By The Numbers
given by yours truly in Melbourne, Nov 5-6, 2008.

If you're in the area, you might also pass this on to other interested colleagues and otherwise contact Anne-Marie Eliseo at or phone: +61-8-8302-3928 for more details. They are trying to figure out if they should run it in Sydney as well. Your feedback could help them.

Wednesday, August 27, 2008

The Valley Ain't What It Used To Be

Important interview in the SF Chron with hi-tech maven, Judy Estrin, where she warns about lagging innovation in the Si Valley and the USA. She is quoted as saying:

"That all sorts of forces, from Wall Street's quarterly profit pressures to worsening government deficits, have undermined support for the forward-looking research on which future products will depend."

I've certainly been complaining for a long time about the excessive influence of Wall St. on shortening capacity planning horizons. Estrin also claims that the environment for innovation in Silicon Valley and the United States has already changed for the worse. Whether you agree everything she says or not, I think her comments are important because there seem to be precious few figureheads who are prepared to stand up and tell as it is.

Updated on Thu Aug 28, 2008: Case in point from Slashdot regarding Alcatel-Lucent (née Bell Labs) yanking the financial plug on basic science "like yer startin' a mower!" (to quote Elaine Benes). As I've said before , the Edison model is dead.

Applying the USL Model to Multivalued Data

A reader was having trouble applying the USL model to his data and asked me to take a look at it. I can't discuss his data because it's private, but I can show you what I did using some simulated data that has the same properties. The data was collected off a production system not a controlled load-test platform, and this brought to the surface two aspects of applying the USL which I had not faced previously:

Saturday, August 23, 2008

It's the PLANNING, Stupid!

The phrase "It's the ECONOMY, stupid!" helped boost Bill Clinton's election prospects in 1992. In 1999, when was having its "CNN moments" (as we called them, back then), I declared that capacity planning seemed to be an oxymoron for many pre-bubble-bursting web sites. They were prepared to throw any amount of money at lots of iron, which presumably meant they understood the "capacity" part (capital expenditure). It's the "planning" part they didn't grok. Planning means thinking ahead. Planning requires investment in the future. If the Financial Dept. can do it, why can't IT?

Thursday, August 21, 2008

GCaP Book Availability

Guerrilla graduate, Greg Rogers, alerted me to the fact that is showing my GCaP book as being "Temporarily out of stock". Sideways, this turns out to be good news. I know some of you will be thinking ahead to Xmas gifts, so don't be dissuaded. :-) I contacted my editor at and here's what's going on.

Back in April, I was busily directing the attention of the GCaP course attendees to the Guerrilla Manual booklet inserted in the back cover when, to their surprise and my chagrin, they discovered that their copies did not have the booklet. Mine did, but it was an older copy. What the ...!? Turns out, it was a production error in the latest printing, which is now in the process of being corrected. The misprint versions have possibly been "recalled" and that's why it is temporarily out of stock. I'm sure Amazon will still be happy to take your order. Thanks, Greg.

Tuesday, August 12, 2008

Scalability Theorems Paper Now Available

As promised, my paper containing the proofs that the universal scalability law is equivalent to the synchronous throughput bound of a machine repairman model of a multiprocessor with state-dependent service rate, is now available from the arXiv preprint server under the title "A General Theory of Computational Scalability Based on Rational Functions," and covers the following topics:

Tuesday, July 29, 2008

How to Recover the Missing X(1) for the USL Scalability Model

When it comes to assessing application scalability, controlled measurements of the type that can be obtained with tools like Grinder or LoadRunner, are very useful because they provide a direct measurement of the throughput, X(N), as a function of the vuser/generator load, N. These data can be input easily into my universal scalability model (USL). To apply USL, however, you need to normalize all the X(N) data to the X(1) value. It often happens that the X(1) value may not have been measured by your QA group or it simply may not be measurable easily. What do you do in that case? You estimate it (carefully).

Friday, July 18, 2008

Mr. Amdahl Calls the Repairman

Back in January, I reported that my Universal Scalability Law (USL) had been proven to be equivalent to the synchronous throughput of the load-dependent machine repairman queueing model. Although I wasn't lying, what I really had was what we call a "sketch" for a proof. The details needed to be filled in, but that was just a question of finding the time to do it. In May, I found time to write the first draft and thought I would be finished shortly thereafter. That attempt ground to a halt for two reasons (you might want to refer to Appendix A in my GCaP book for the background):

  1. Simulations that supported the theorem involved a barrier synchronizer, and for this to work continuously, my colleague Jim Holtman, discovered that the distribution of parallel execution times (with mean 'think' time Z) could only be deterministic (D). That's a special case of the repairman: D/M/1//N, whereas the equations in my proof show quite clearly that it must work for M/M/1//N.
  2. There's a theorem in queueing theory (Bunday and Scraton, 1980) which states that what holds for the repairman (M/M/1//N) also holds for a more general source of requests viz., G/M/1//N. Since G is a superset of the distributions D and M, this theorem suggests that our simulations probably shouldn't be restricted to D-distributed think/execution times as observed in (1). Or should they?

Musical Chairs at AMD

It looks like Intel's very aggressive pace for technology advancement, which I have been tracking loosely over the past 18 months, is really starting to hurt AMD. The response from AMD, however, may represent continued dithering at the executive management level.

Monday, July 14, 2008

Guerrilla Data Analysis Class - Seats Still Available

Most operating systems are capable of collecting hundreds of system and performance metrics every second. Even if you only record them once an hour, after a week you will have more than 50,000 samples; after a month you will be staring at almost a quarter of a million samples! But data are just data. How do you extract performance information out of all those data? Easy! You attend our new and expanded 5-day Guerrilla Data Analysis class, here in California.

In this class, computer engineering and statistics expert Prof. David Lilja presents an easy introduction to statistical methods and finally leads us into the topic of Design of Experiment (DOE) methods applied to performance and capacity planning data.

Having established the foundation theory, R expert, Jim Holtman will show you how to apply DOE and other statistical techniques using example case studies.

You can register for the class, and book your hotel room, online. Book early, book often! We look forward to seeing you in August.

Saturday, July 12, 2008

Apple IT Dies on iPhone 3G Launch

It's great to be popular, but hell to be the rage.

In the aftermath, Apple managed to sell 1 million iPhones in just 3 days cf. the same number of the original iPhone in 2.5 months. Why should you care? Mobile devices like this are actually computers, not just phones. The iPhone runs MacOS X; same as mac laptops. In my view, this and similar devices represent the commodity computer of the future.

Wednesday, July 9, 2008

Back from the Old DDR

Read this to the tune of "Back in the USSR".

I spent part of last month in eastern Germany (former DDR) where there is a decided lack of internet connectivity (hence, no blog entries), even after west Germany (FDR) has thrown a considerable amount of euros to bring the eastern economy up to speed. Hotels either don't offer internet at all or want an arm and a leg for it, if they do.

As far as I can tell, eastern hotels (most of which really don't have the inclination to understand IT; just like hotels in the USA) have let Deutsche Telecom swoop in monopolitically to set up internet packages whereby they can charge 9 euros (a whopping $14 USD) for just 1 hour online, unless you are a card-carrying DT customer, in which case you are entitled to some kind of discount. After resisting for days, I eventually broke down just to prevent my web mailbox from overflowing. These packages are affectionately termed "Hot Spots"; a term possibly meant to confuse tourists like me who naturally jump to the conclusion that it means New York style free wi-fi. It's wi-fi ("WLan") all right, but at a very hot price.

Amazon and Google Discover Erlang

Erlang the language, that is.

VMware CEO Walks

VMware CEO, Diane Greene, stepped down abruptly on Tuesday, sending shares down nearly 25%. No reason was given but the company had warned revenue for the quarter ending June 30 would be below its predicted 50% growth compared with last year. It could also be partly a reaction to the commercial marketplace heating up with Microsoft, Sun Microsystems, Hewlett-Packard and Citrix (backed by IBM) having all built or acquired similar virtualization technologies.

On the FOSS scene, we have VirtualBox as a replacement for VMWare Fusion or Parallels.

Saturday, May 24, 2008

Instrumentierung – die Chance für Linux?

My latest article for the German publication Linux Technical Review appears in Volume 8 on "Performance und Tuning" and discusses a possible roadmap for future Linux instrumentation and performance management capabilities. The Abstract reads:
  • German: Linux könnte seine Position im Servermarkt ausbauen, wenn es dem Vorbild der Mainframes folgte und deren raffiniertes Performance-Management übernähme.
  • English: Linux could be in a position to expand its presence in the server market by looking to mainframe computer performance management as a role model and adapting its instrumentation accordingly.

Topics discussed include a comparison of time-share scheduling (TSS) with fair-share scheduling (FSS) and the Linux Completely fair scheduler (CFS), how to achieve a more uniform interface to performance and capacity planning measurements, and the kind of advanced system management capabilities available on IBM System Z for both their mainframes and clusters.

Thursday, May 15, 2008

Is BitTorrent Being Blocked on Your Block?

Ever since Comcast was sprung by the AP, last fall, for surreptitiously blocking or retarding BT traffic with forged packets, other ISPs, e.g., Road Runner, Charter, Bell Canada and Cox TOS, have also started to block P2P traffic, despite public criticism of their rationale. There are a number of anti-blocking tools (least gyrating web-ads page) and services available to help you determine if your packets and ISP service is being tweaked. Two FOSS tools that are readily available are: Glasnost from Germany, and Pcapdiff from EFF.

Wednesday, May 14, 2008

Spam Still Pays

This interesting nugget appeared in a recent judgement against notorious spammerati Sanford Wallace and Walter Rines. According to court records, "Wallace and Rines sent 735,925 messages and earned over $500,000 in the process." That's better than a 67% hit rate! Of course, those ill-gotten gains pale when compared to the award of $230 mil granted to, who filed the lawsuit last year. But even getting a piece of the $500 K might be a bit tricky since the pair failed to appear in court and have since gone missing. Wallace already has an outstanding $4 mil (peanuts?) fine from the FTC. All in all, looks like crime still pays.

Monday, May 12, 2008

Preposterously Parallel iPods

Here's a question: How many FLOPs in an iPod?

Climatologists, up the road here at LBL, claim that a supercomputer using about 20 million embedded microprocessors, such as those found in cellphones, iPods, and other consumer electronic devices, would deliver useful climate simulation results at a cost of $75 million to construct. A comparable supercomputer could cost closer to $1 billion. Based on a recent post, I'd be wanting to see the front-end compiler system that can upload 20 million processors.

Wednesday, May 7, 2008

Visual Tornadoes and Cyclones

Although physical tornadoes and cyclones are in the news at the moment, there are also the virtual kind or more significantly for PerfViz, the visual kind.

For a long time, I've thought it would be cool to be able to visualize system performance as a shape but was never quite sure what that meant. My role model has been SciViz, where complicated system dynamics like the time-development of tornadoes can be visualized in 3D animations. More recently, the cyclone paradigm has been used for textual analysis based on word repetition (The novel "Frankenstein" is show above). The more a word is used, the larger is its cube. Blue cubes are words that are unique, red cubes are not. The diameter of the rings is determined by the size of the paragraphs. Who woulda thunk it?

The closest I've come to producing performance data as a "shape" is this:

which shows processor %user, %system, and %idle time for a 72-way SMP running a transaction workload on ORACLE 10g over a 20 minute measurement period. Data supplied by Tim Cook of Sun Microsystems. The time-development of the data (not shown here) is not too far removed from the tornado animation in the first figure.

Monday, May 5, 2008

Microsoft Discovers the Dumpster Datacenter

OK, not exactly a dumpster but something slightly bigger; a shipping container. Hello!? Google has been developing this concept for years with Sun and IBM not far behind in adopting it. The new wrinkle is that Google has now been awarded a patent on it.

Supply Chain Factoid: There are so many more (full) shipping containers coming from Asia to the USA and Europe than going the other way, that it is less cost-effective to store the empties than to simply scrap them and make new containers as needed.

Saturday, May 3, 2008

Object, Time Thyself

For quite a while (6 years, to be exact), I've thought that the only sane way to address the problem of response-time decomposition across multi-tier distributed applications, is for the software components to be self-timing. In fact, I just found the following old email which shows that I first proposed this concept (publicly) at a CMG vendor session conducted by Rational Software (now part of IBM) in 2002:

Friday, May 2, 2008

First Guerrilla Boot Camp Rookies Survive

The first "Guerrilla" class for the year and the first Level I Boot Camp ever, seems to have gone swimmingly. Here is some example feedback:

Tim McCluskey wrote on 4/30/08 12:29 PM:

The class was great! I'm glad that I didn't listen to the 2 people that gave me the impression that it or you were going to be over my head.

Vladimir Begun wrote on 4/30/08 20:33:36 -0700:

... it was great! A clear and horizon-expanding presentation of an actual experience in the capacity planning. About right for the jump-start! Eager to attend the level II class.

More people enrolled than we had hoped for in the shortened time-frame that was available to advertise it, and they all reported liking the hotel, sleeping rooms, seminar room, food, and especially the free wifi everywhere. They were also grateful for being able to use the ensuite bathroom across the hall instead of having to walk to the other end of the hotel corridor. :-)

We'll do it all again, in a couple of weeks but at Level II, this time.

Pay per VPU Application Development

So-called "Cloud Computing" (aka Cluster Computing, aka Grids, aka Utility Computing, etc.) is even making the morning news these days, where it is being presented as having a supercomputer with virtual processor units just a click away on your home PC. I don't know too many home PC users who need a supercomputer, but even if they did and it was readily available, how competitive would it be given the plummeting cost of multicores for PCs?

Ruby on de-Rails?

Here we go ... According to a recent post on TechCrunch, is planning to abandon Ruby on Rails after two years of fighting scalability issues. The candidates for replacing RoR are rumored to be PHP, Java, and/or just plain Ruby. On the other hand, Twitter is categorically denying the rumor saying that they use other development tools besides RoR. This is typical of the kind of argument one can get into over scalability issues when scalability is not analyzed in a QUANTIFIED way.

As I discuss in Chap. 9 of my Perl::PDQ book, the qualitative design rules for incrementally increasing the scalability of distributed apps go something like this:

  1. Move code, e,g., business logic, from the App Servers to the RDBMS backend and repartition the DB tables.
  2. Use load balancers between every tier. This step can accommodate multi-millions of pageviews per day.
  3. Partition users into groups of 100,000 across replicated clusters with partitioned DB tables.

All the big web sites (e.g., and do this kind of thing. But these rules-of-thumb beg the question, How can I quantify the expected performance improvement for each of these steps? Here, I only hear silence. But there is an answer: the Universal Scalability Law. However, it needs to be generalized to accommodate the concept of homogeneous clustering, and I do just that in Section 4.6 of my GCaP book.

The following slides (from 2001) give the basic idea from the standpoint of hardware scalability.

Think of each box as an SMP containing p-processors or a CMP with p-cores. These processors are connected by a local bus, e.g., a shared-memory bus; the intra-node bus. Therefore, we can apply the Universal Scalability model as usual, keeping in mind that the 2 model parameters refer to local effects only. The data for determining those parameters via regression could come from workload simulation tools like LoadRunner. To quantify what happens in a cluster with k-nodes, an equivalent set of measurements have to be made using the global interconnect between cluster nodes; the inter-node bus. Applying the same statistical regression technique to those data gives a corresponding pair of parameters for global scalability.

The generalized scalability law for clusters is shown in the 5th slide. If (in some perfect world) all the overheads were exactly zero, then the clusters would scale linearly (slide 6). However, things get more interesting in the real world because the scaling curves can cross each other in unintuitive ways. For example, slide 7 "CASE 4" shows the case where the level of contention is less in the global bus than it is the local bus, but the (in)coherency is greater in the global bus than the local bus. This is the kind of effect one might see with poor DB table partitioning causing more data than anticipated to be shared across the global bus. And it's precisely because it is so unintuitive that we need to do the quantitative analysis.

I intend to modify these slides to show how things scale with a variable number of users (i.e., software scalability) on a fixed hardware configuration per cluster node and present it in the upcoming GCaP class. If you have performance data for apps running on clusters of this type, I would be interested in throwing my scalability model at it.

Sunday, April 27, 2008

Don Knuth on Open Source, Multicores and Literate Programming

Donald Knuth, the father of TeX and author of the long unfinished multi-volume set of books entitled "The Art of Computer Programming", sounds off in this interesting interview.

His comment on unit testing (or an overzealous reliance on it) seems a bit obscured here. I am certainly more inclined to concur with his other quote: "early optimization is the root of all evil," because unit testing tends to promote that bad strategy with respect to system performance. Some personal war stories describing exactly that will be delivered this week in my Guerrilla Boot Camp class.

However, do read and heed what he says about multicores and multithreaded programming. It should sound familiar. BTW, where he apparently says "Titanium", he means Itanium.

His riff on "literate programming" is a bit of a yawn for me because we had that capability at Xerox PARC, 25 years ago. Effectively, you wrote computer code (Mesa/Cedar in that case) using the same WYSIWYG editor that you used for writing standard, fully-formatted documentation. The compiler didn't care. This encouraged very readable commentary within programs. In fact, you often had to look twice to decide if you were looking at a static document or dynamic program source. As I understand it, Knuth's worthy objective is to have this capability available for other languages. The best example that I am aware of today, that comes closest to what we had at Xerox, is the Mathematica notebook. You can also use Mathematica Player to view any example Mathematica notebooks without purchasing the Mathematica product.

Wednesday, April 23, 2008

Postscript to "When is 325,000 Greater Than 325,425?"

When I originally blogged this item, I had an idea about an alternative interpretation but I couldn't quite express it. Now, I think I can.

When we see a high-precision number, we perceive it as being associated with something particular (e.g., this pig). When we see a rounded number, even if it is smaller in magnitude, we perceive it as being associated with an interval or collection of numbers (e.g., the collection of pigs in the drawing). That's more or less what's going on between Sylvie and Bruno; she's thinking round numbers about the collection of pigs, whereas Bruno is focused on the particular four pigs that he can see immediately.

An interval is a range of numbers that could encompass the precise number and therefore, by definition, exceed it. So, for example, $325,425 is larger than $325,000 in absolute magnitude, but the latter could be interpreted (i.e., perceived in our mind) as representing the interval $325,000 to $326,000, which encompasses $325,425. Hence, the particular may be perceived to be smaller than the general. The Cornell researchers did not test for this effect.

Sunday, April 20, 2008

When is 325,000 Greater Than 325,425?

According to a recent Cornell business school report, the answer is, when it involves money. The statistical study actually involved housing prices (rather apropos, given the meltdown in the mortgage market), so that a house priced with a "precise" number like $325,425 (i.e., more significant digits) was perceived to be cheaper than one priced at the rounded down value of $325,000.

Interestingly enough, prices like $299,999 (akin to the usual sales ploy one sees in department stores and on TV) were deliberately excluded from the Cornell study because numbers ending in all 9's, although a precise number (by their definition), is considered too close to the rounded value ($300,000) to give a statistically reliable distinction.

One has to wonder, what are the implications for the way capacity planning reports are perceived? We'll discuss that point next week as part of the section on significant digits in the Guerrilla Boot Camp class.

Even if you think such statistical reports might be a bit suspect, you've gotta love their opening rubric from Lewis Carroll:

`I'm counting the Pigs in the field!' (Bruno, looking out the window)
`How many are there?' I enquired.
`About a thousand and four,' said Bruno.
`You mean "about a thousand",' Sylvie corrected him.
`There's no good saying "and four": you can't be sure about the four!'

`And you're as wrong as ever!' Bruno exclaimed triumphantly.
`It's just the four I can be sure about;
'cause they're here, grubbling under the window! It's the thousand I isn't pruffickly sure about!'

--- "Sylvie and Bruno Concluded" (1893), Ch. 5, p. 3.

Guerrilla Manual Updated

The section of the Guerrilla Manifesto that outlines my
Universal Scalability
law, has been updated with the following diagrams,

which show the explicit components of the model (equation 1). Such effects are now being recognized more widely, so I'll be explaining more about this in my Guerrilla Boot Camp class, next week.javascript:void(0)

Saturday, April 19, 2008

The Woolliness of the Wild Wild Web

WWW is the acronym for World Wide Web, but it more often seems to stand for the Wild and Woolly Web.

Call me old-fashioned, but one of things the drives me up the wall about publication on the web in general, and technical expositions in particular, is the lack of both time-stamps and citations. These two things have existed in the scientific media even before formal journal publication. For example, 17th century scientists like Newton and Hooke, wrote missives to each other and it was convention then, as it is today, to commence a letter with the date. That's how we know that Hooke was very close to coming up with the law of gravitation that is now attributed to Newton (also aided by the latter meticulously eliding all reference to Hooke after the first edition of The Principia). Could we know those things today if they had been using the Web? It's not clear. It depends. And that's the problem; lack of consistency and a lack web tools to enforce consistency.

Friday, April 11, 2008

Internet Needs Flow Control

In a post by Larry Roberts (co-founder of the Internet), he proposes a flow control solution to congestion control problems on the Internet. This is an important ongoing issue ever since the Internet collapsed circa 1986. Because it relates to queueing policies, I discuss this problem in Section 1.8.3 "Metastability on Networks" of my Perl::PDQ book.

Roberts claims, contrary to popular belief, the problem with congestion is the networks, not the TCP protocol. Rather than overhaul TCP, he says, we need to deploy flow management and selectively discard no more than one packet per TCP cycle. Flow management is the only alternative to probing into everyone's network and the only way to fairly distribute Internet capacity. The comments on his post are also worth reading because they compare his proposal with already defined protocols, such as WRED and DiffServ.

Podcast: "Diving into Capacity Planning"

A podcast that I did for TeamQuest Corporation, back in December, is now available. It's a somewhat unconventional take on the motivations for doing CaP, based on taking into account the apparently frustrating but otherwise very realistic perspective of management. During the podcast, I refer to the CMG Keynote given by Jerred Ruble (CEO of TeamQuest Corp.) Here is the abstract of his presentation entitled, "Is Capacity Planning Still Relevant?" (click to enlarge)

Simple registration required to download the 25 MB mp3 file. This podcast also gives you an idea of some the things we will be treating in the Guerrilla Boot Camp class on April 28-29, 2008.

Sunday, March 30, 2008

Heathrow T5 Killed by Queueing

The British might seem to be alone right now when it comes to airport system fiascos, but the good ole USA is just as good, if not better, at mangling baggage systems. So, what happened? Well, of all the lame excuses, finger pointing and spin-doctoring for the media, this item caught my attention from a performance analysis perspective:

"But the underground conveyor system became clogged because staff failed to remove luggage quickly enough at the final unloading stage. So the system shut down. It's like a shopper putting too many goods on the supermarket check-out belt."

Because the baggage transfer area is tightly secured (we hope), there are no clandestine videos available from passenger cellphones. However, the following queue-theoretic simulation reveals what likely happened.

Click on the image to start the simulation.

Wednesday, March 26, 2008

Visualize This

Calling all those interested in improving the visualization of performance data (PerfViz). The following discussion group

Google Groups
Performance Visualization
Visit this group

has now been established. To join the group, just enter your email address and hit Subscribe.


Prospective authors interested in presenting a paper on PerfViz at CMG 2008, have until May 16th to submit an abstract and until June 13th to write a draft manuscript.

Building Perl PDQ with VisualStudio

PDQ user Alex Podelko reports a gotcha when building Perl PDQ with VisualStudio. His solution has been posted to the PDQ download page. Thanks, Alex!

Tuesday, March 25, 2008

Hickory, Dickory, Dock. The Mouse Just Sniffed at the Clock

Following the arrival of Penryn on schedule, Intel has now announced its "tock" phase (Nehalem) successor to the current 45 nm "tick" phase (Penryn). This is all about more cores (up to 8) and the return of 2-threads per core (SMT), not increasing clock speeds. That game does seem to be over, for example:

  • Tick: Penryn XE, Core 2 Extreme X9000 45 nm @ 2.8 GHz
  • Tock: Bloomfield, Nehalem micro-architecture 45 nm @ 3.0 GHz

Note that Sun is already shipping 8 cores × 8 threads = 64 VPUs @ 1.4 GHz in its UltraSPARC T2.

Nehalem also signals the replacement of Intel's aging frontside bus architecture by its new QuickPath chip-to-chip interconnect; the long overdue competitor to AMD’s HyperTransport bus. A 4-core Nehalem processor will have three DDR3 channels and four QPI links.

What about performance benchmarks besides those previously mentioned? I have no patience with bogus SPECxx_rate benchmarks which simply run multiple instances of a single-threaded benchmark. Customers should be demanding that vendors run the SPEC SDM to get a more reasonable assessment of scalability. The TPC-C benchmark results are perhaps a little more revealing. Here's a sample:

  • A HP Proliant DL380 G5 server 3.16GHz
    2 CPU × 4 cores × 1 threads/core = 8 VPU
    Pulled 273,666 tpmC on Oracle Enterprise Linux running Oracle 10g RDBMS (11/09/07)

  • HP ProLiant ML370G5 Intel X5460 3.16GHz
    2 CPU × 4 cores × 1 threads/core = 8 VPU
    Pulled 275,149 tpmC running SQL Server 2005 on Windows Server 2003 O/S (01/07/08)

  • IBM eServer xSeries 460 4P
    Intel Dual-Core Xeon Processor 7040 - 3.0 GHz
    2 CPU × 4 cores × 2 threads/core = 16 VPU
    Pulled 273,520 tpmC running DB2 on Windows Server 2003 O/S (05/01/06)

Roughly speaking, within this grouping, the 8-way Penryn TPC-C performance now matches a 16-way Xeon of 2 years ago. Note that the TPC-C Top Ten results, headed up by the HP Integrity Superdome-Itanium2/1.6GHz at 64 CPUs × 2 cores × 2 threads/core = 256 VPUs, are in the 1-4 million tpmC range.

The next step down is from 45 nm to 32 nm technology (code named Westmere), which was originally scheduled for 2013. Can't accuse Intel of not being aggressive.

Saturday, March 22, 2008

Corrigenda Available for GCaP Book

Looks like it's time to start a corrigenda page for my book, Guerrilla Capacity Planning: A Tactical Approach to Planning for Highly Scalable Applications and Services.

Special note added regarding J2EE/WebLogic listen threads in Chapter 7 and how they control application scalability.

You can submit an erratum online.

Wednesday, March 19, 2008

International Training at Bargain Prices

Google tells me that this blog has a lot of international readers. Additionally, I'm often asked if I plan to present my performance training classes at random locations around the world. Unfortunately, the logistics of doing that is much more difficult than is realized by the people who ask that question. But now, there is a solution! The U.S. dollar has fallen significantly against most other currencies, so it's cheaper for you to travel here, than for me (to charge you) to travel there. And who doesn't want to visit San Francisco? :-)

The U.S. dollar prices shown on the 2008 Training Schedule (PDF) can be converted to another currency using any of the following selection of multipliers:

    Australia ..... 1.08
    Brazil ........ 1.71
    Canada ........ 0.99
    China ......... 7.08
    Euro .......... 0.63
    India ......... 40.2
    Japan ......... 98.23
    Korea ......... 1008.4
    Malaysia ...... 3.15
    Switzerland ... 0.99
    Taiwan ........ 30.72
    Thailand ...... 31.1
    U.K. .......... 0.49

If your currency is not shown here, try this online currency converter. I look forward to seeing more international students in our classes this year.

Monday, March 17, 2008

USA High Tech R&D Trending Down

We've come a long way since Thomas Edison, baby! Among other things, the Wizard of Menlo Park (the one in Joizee, not California) also invented the concept of the modern industrial research lab; existing outside and independently of the cloisters of academia, where most significant research was done prior to Edison. So effective was Edison's Yankee ingenuity, that it was ultimately embraced by such emblematic American corporations as AT&T (Bell Labs), HP (Labs), IBM (Watson Labs), and Xerox (PARC), as well similar companies in Europe (Philips, Siemens) and, of course, Japan. In fact, 25 years ago, Japan had the USA so threatened by its growing economic clout that it would have been considered suicidal for the U.S. not to invest heavily in R&D.

Now, we read that U.S. high-tech R&D is trending downward even further; the PC language is "narrowing our focus" . Like the continual reduction in the Fed Prime Rate, how low can you go before you have no effect? Moreover, how can such trends have been considered suicidal 25 years ago but embraced today? Japan has not gone away, and now China and India also loom as respectable tech competitors in their own right. Not being an economist, I can only think of one explanation: Wall Street. Actually, it's not exactly a new trend because it began more subtly around 15-20 years when the aforementioned corporations slowly started to divest themselves of the large-budget Edison model. Why would they do that? It's around that same time that the U.S. population at large started becoming more invested in Wall St., either directly or indirectly (e.g., retirement accounts). This trend has since been adopted in places like Europe and Australia.

The Street demands short-term gains be reported quarterly, no matter how that goal is accomplished; witness the current sub-prime banking debacle as one potential outcome of trying to meet such insane demands. But if profits in the USA are up (as they measureably are--or have been until very recently), why is there less money going into R&D? Shouldn't the percentage of profits, at least, remain constant? To answer this question, I would point to none other than "Mr. Capitalism" himself, Warren E. Buffet (see if you can guess his point before clicking on the link). Just as the deregulated financial industry has imploded (again--lest we forget the S&L debacle of the late 80's), I think Edison would be appalled at the self-destructive shift of profits out of R&D and into executive compensation packages. Sadly, it seems the Wizard of Menlo Park continues to be overshadowed by the Wizards of Wall Street. OK, end of rant.

Saturday, March 8, 2008

Watch Your Knees and Queues

Beware of optical illusions!

The above plot, showing the normalized response times (R/S) for an M/M/m queue (i.e., a single waiting line with m servers), popped up several times at Hotsos 2008. The M/M/m queue can be employed to model the performance of multiple Oracle processes. Here, the curves correspond to m = 1 (black), 2, 3, 9, 16 (blue) plotted against average server utilization.

Friday, March 7, 2008

Hotsos 2008: Day 3

Only two things happened today; I gave my presentation on "Better Performance Management through Better Visualization Tools" and I met with Bob Sneed because he also asked my to review his presentation.

Hotsos 2008: Day 2

Tanel Poder continued his theme of better ways to collect Oracle performance data by demonstrating how his "Sesspack" (Oracle session level) data could be visualized using VBA calls to Excel charting functionality. He used Swingbench as a load generator for his demos. Afterwards, I spoke with him about my talk tomorrow and he said he was interested and would attend.

Monday, February 25, 2008

Adobe AIR. The More Things Change?

Erm ... Call me old fashioned but, apart from the implementation details such as AJAX, Flash, and yadda, yadda, isn't Adobe AIR like totally how the user interface worked prior to Netscape? Say, America Online circa 1992? I think it was called a client-side application. What am I missing here? Oh, I get it! Web 2.0 eliminates the marketing compulsion to put CDs in your airline food.

Paravirtualization in VMWare Server

Guerrilla alumnus Peter Lauterbach provides some updates on improved performance transparency in VMware ESX Server 3.5 (the bare metal virtualization product).

"Paravirtualization has been available in the VMware Workstation product since version 6, but it also requires guest kernel changes. Linux kernel 2.6.20 and above support pv, look for CONFIG_VMI=y in kernel config. The latest Ubuntu release has this enabled by default. You also need to check the paravirtualized kernel flag in the VMware Workstation and ESX Server Advanced settings under the Options tab.

Paravirtualization in Linux has quite a few moving parts to it, and affects mostly performance metrics and timekeeping functions. The best example is %steal time, which is the time that the virtual guest wanted to run, but was not able to, usually due to contention with other VM guests. This time was previously only visible to the virtual host, but can now be seen by the guest. Paravirtualized guests do run faster, and certainly feel more responsive when using a Linux GUI like KDE on a virtual guest.

Other advances from VMware are things like "VMDesched", which is an experimental feature in VMware Tools that creates a thread that is charged all the involuntary preemption time from the physical CPU."

Thanks, Peter.

Thursday, February 21, 2008

Cool Crypto Attack Gives Cold Comfort

A team of academics at Princeton University, together with industry and independent researchers has demonstrated a new class of computer attacks that compromise the contents of supposedly secure memory systems, particularly in laptops. The attack exploits the relatively slow decay of memory bits (seconds to minutes) that often contain disk encryption keys. The usual decay rate can be slowed even further by spraying the RAM chips with the compressed gas in a typical can of anti-static spray. A video presentation and the research paper are available at the Princeton site.

Saturday, February 16, 2008

Web 2.0 Meets Error 33

Apparently Amazon's Elastic Cloud snapped yesterday and havoc rained down on a number of Web 2.0 sites. This is unfortunate because the same kind of technology was deployed very rapidly (elastically?), exactly one year ago, to help search for missing computer scientist and yachtsman, Jim Gray.

When I was at Xerox PARC, we had a term for this kind of failure mode: Error 33. Error 33 states that it is not a good idea for the success of your research project to be dependent on the possible failure of someone else's research project. This term was coined by the first Director of Xerox PARC, Dr. George Pake and the nomenclature is reminiscent of Catch 22.

Error 33 is an all too appropriate reminder that a lot of Web 2.0 technology, which is hyped as ready for prime-time, is really still in the R&D phase. It's probably only very annoying when SmugMug is off the air for several hours, but mission-critical services like banks and hospitals should approach with caution. Achieving higher reliability is only likely to come at a higher premium.

Board from the Back of the Bus (maybe not)

When boarding a tour bus, the driver often tells you to occupy seats at the back of the bus first. This protocol is assumed to be more efficient than filling seats from the front because people block the aisle while stowing their carry-on baggage and thereby impede the flow. So, back-filling is more efficient than front-filling but is it optimal? The same procedure is used by airlines that implement boarding by groups A, B, C, etc. Group A is usually seated at the rear of the aircraft. There are some variants with aircraft boarding (e.g., window seats before aisle seats) that also help to distribute the passenger weight more evenly. The question remains, however, is it optimal?

An astrophysicist recently decided to look into this question more carefully using Monte Carlo simulations and found some surprising results. He unexpectedly discovered that the common rear boarding procedure is actually the second worst procedure, since it is only slightly more efficient than boarding front-to-back! So surprised was he, that at first, he thought there was a bug in his code. Then it became apparent that there was something more subtle going on. MC sims showed that an optimal boarding method was for passengers to board 10 at a time in every other row, since loading luggage requires about two aisles of space. In this way, passengers are either stowing luggage or sitting in their seats, rather than waiting in the aisle, as they do in the other two protocols. Depending on the size of the aircraft, this boarding procedure produces a speed up of 5 to 10 times over the worst case. Of course, disembarking is still LIFO. :-)

I wonder if this result could have applications in the context of computer or network performance analysis and capacity planning?

Tuesday, February 12, 2008

Guerrilla Training Schedule: A Two Point Landing

After many trials and tribulations, the 2008 training schedule has now stabilized at our new location: Larkspur Landing in Pleasanton, which is only about a mile away from the previous hotel location. The stumbling block for us was not room rates but outrageous contract penalty clauses for class cancellations. Apparently, hotel franchises, which are going to hurt this year in the already obvious economic downturn (I don't care what you call it), have suddenly decided they are no longer in the service/hospitality industry but the gold mining business.

Monday, February 4, 2008

Guerrilla Training Schedule Updates

Because of necessary hotel changes, we are still in the process of organizing Guerrilla Training Schedule for 2008. The bad news is, we still haven't been able to finalize the hotel. The good news is, we are converging. With any luck, everything should be wrapped up this week. Unfortunately, these ongoing negotiations have delayed our normal advertising schedule and one casualty is the new Guerrilla Boot Camp class, which we now have had to move out to July. We apologize to those who will be inconvenienced.

The latest schedule updates can always be found on the Classes page.

Friday, February 1, 2008

Penryn Performance. The Envelope Please!

Having kept pretty much to its promised schedule for the Penryn microprocessor ...

Intel is now significantly ahead of the industry with the production of 45 nm parts using the new high-K dielectric materials. The claims for the new Hafnium oxide-metal gate technology included:

  • Approximatley 2x improvement in transistor density, for either
    smaller chip size or increased transistor count

  • Approximatley 30% reduction in transistor switching power

  • Better than 20% improvement in transistor switching speed or 5x
    reduction in source-drain leakage power

  • Better than 10x reduction in gate oxide leakage power

Wednesday, January 30, 2008

Beware VMWare!

Hot on the heels of the Cisco hyper-mega-switch announcement and Yahoo announcing a reduction in workforce despite increasing profits, comes the nose-dive of VMWare's stock price; losing one-third it's value in a single day. Keeping in mind that Wall Street is capable of either irrational exuberance or irrational pessimism, the events pertaining to Yahoo and VMWare are most likely an expression of the latter. Both companies have solid business plans.

From the performance angle, however, it may also be that the honeymoon period is now over in part because VMWare is a victim of its own success. Not only has all the hype surrounding virtualization and consolidation worn a bit thin these days, but it has also attracted the big guns---Microsoft and Oracle---into the market. And customers are not doubt becoming aware that consolidation doesn't always translate into less MIPS or more greenness. The overheads of virtualization can be very significant. The problem for us performance weenies is knowing what are those overheads in a QUANTITATIVE way. As I've stated before:

All virtualization is about illusions and although it is perfectly reasonable to perpetrate such illusions onto a user, it is entirely unreasonable to propagate those same illusions to the performance analyst.

So, here's an opportunity for VMWare to differentiate itself in the madding crowd of new VMM vendors; focus on providing more whistles and less bells. And you (Dear reader), as John Q. Customer/Analyst, should demand it (even if by proxy). If you don't make the ultimate performance issue known to management, how can they be expected to pressure the vendors?

Monday, January 28, 2008

Cisco Systems: "It's the switch, stupid!"

Today, Cisco Systems (San Jose, California) announced its mother of all switching platforms, the Nexus 7000 Series, aimed at what it calls Data Center 3.0 (analogous to Web 2.0, I presume. I missed Data Center 2.0). Cisco is essentially trying to eliminate the need for separate storage networks, server networks, routing, switching and virtualization, by combining them all into a single unified fabric and managing it through Cisco's new proprietary NX-OS ("nex-os", get it?) operating system.

The Nexus 7000 will deliver up to 15 Tbps of switching capacity in a single chassis, with 512 ports for 10 Gbps ethernet, and eventually it is slated to be delivered with 40 Gbps and 100 Gbps ports. Some of the claimed performance speeds-and-feeds appear rather breathtaking:

  • Copy the entire Wikipedia database in 10 milliseconds.
  • Copy the entire searchable Internet in 7.5 Minutes.
  • Download all 90,000 Netflix movies in 38.4 seconds.
  • Send a high-resolution 2 megapixel photo to everyone on earth in 28 minutes.
  • Add a Web server in 9 seconds rather than 90–180 Days.
  • Transmit the data in all U.S. academic research libraries (estimated at more than 2,000 TB) in 1.07 seconds.

If nothing else does it, the 3 significant digits in the last claim tells you this is marketing-speak (read: calculated using max bandwidth assumptions), so a liberal dusting of sodium chloride is recommended.

The concept of a "data center" is currently undergoing a serious transformation and it will be interesting to see how this kind of mega-switch stacks up against alternative approaches, such Google's Data Center in a Box.

Friday, January 18, 2008

Scalability Law as Queueing Model Proven

It never rains in California, it just pours. Not only have we had a lot of seasonal rain lately but it seems to be the season for proofs. In 2002, I proved that Amdahl's law is equivalent to a special kind of queueing behavior. This particular connection with queueing theory had not been made before. Here's a restatement of that theorem.

Wednesday, January 16, 2008

Sun to Purchase MySQL

This could be good news for Oracle. 8-\

Continuing a string of surprising announcements, Sun Microsystems today said it plans to buy the makers of MySQL open-source database software for almost $1,000,000,000 (I like to see all those zeros). Sun does have a lot of cash burning a hole in its pocket, but it also has a less than stellar track record when it comes to acquisitions.

Monday, January 14, 2008

What to Do with Wobbly Numbers in PDQ

Peter Altvogt (Germany) reported an interesting numerical effect while using the load-dependent server model in Section 6.7.11 of "Analyzing Computer System Performance with Perl::PDQ". The default parameters in are set to N = 15 users and M = 3 maximum processes allowed in the sub-system. The PDQ model calculates the joint probability distribution Pr(j|n) of the queue length at the load-dependent server. For these parameters the mean queue length is 4.50 users.

Saturday, January 12, 2008

Erlang Explained

During the GCaP class, last November, I mentioned to my students that I was working on a more intuitive derivation of the Erlang B and C formulae ( the English wiki link to Erlang-C is wrong) associated with the multi-server or M/M/m queue. This queue is very important because it provides a simple performance model of a multiprocessor or multicore systems, amongst other things. When I say simple here, I mean the queueing model is "simple" relative to the complexities of a real multiprocessor (e.g., it does not include the effects of computational overhead). On the other hand, the mathematics of this particular queueing model is not simple. Not only do we need to resort to using some kind of computational aid to solve it (some people have built careers around finding efficient algorithms), the formulae themselves are completely unintuitive. During that class I thought I was pretty close to changing all that; to the point where I thought I might be in a position to present it before the class finished. I was wrong. It took a little bit longer than a week. :-)

Guerrilla Training Schedule for 2008

The preliminary Guerrilla Training Schedule for 2008 has been posted. The embedded PDF includes a brief slide-show of extracts from the various classes. It also includes hyperlinks to the Course Content pages. Some browsers may render the PDF differently. If you have problems, you might try upgrading to the latest Acrobat Reader. The most significant change is that the GDAT class has now been extended to a full 5 days with the addition of Jim Holtman as an instructor, who is "Mr. Wizard" when it comes to using and explaining how to do statistical data analysis with R (or S-Plus).

Please bear with us while we sort out the situation with the hotels. The Crowne Plaza now has new ownership and is undergoing a complete renovation. They are telling us they will be open again by March, but we have to decide if we need to hedge our bets on that claim. It will get sorted out shortly, but if you are planning on attending a Guerrilla class, please make sure you check the schedule page for the latest information.

Hotsos Oracle Symposium 2008

I've been invited to speak again at the Hotsos Oracle Symposium, March 2-6 in Dallas, Texas. I'm more than happy to do this because I found last year's symposium to be a first class operation with plenty of great speakers and an attentive audience who were very interested in performance analysis and capacity planning in general, in addition to it's applicability for ORACLE.

Just as an aside, if you look at the Hotsos company logo at the top of their web pages, you'll see some equations or bits of equations. The first of these is the denominator of the famous Erlang-C function (A. Erlang, 1917). More on that in an upcoming blog entry.

Looking for Guerrilla Class Pix

First, I should say Happy New Year! I don't think it's too late to say that. Is it? Personally, I've been buried in Mathematica since I came back from
CMG 2007
. In fact, I need a vacation!!!

Anyway, I'm looking for pix (JPEGs) that people have taken over the years while attending my Guerrilla classes. In particular, one year (2003, 2005?) there were some shots taken of the entire group outside the Crowne Plaza in the afternoon sunlight. I was emailed a copy of them at the time by the person who took them, but since upgrading computers N-times, I cannot find them. :-(

Please let me know if you have any such photos.