How to Quantify Scalability

How to Quantify Scalability: Synopsis of The Universal Scalability Law (USL), has just been posted in PDF format for improved readability. I did this post haste so, reporting any typos, broken links, etc., is always appreciated.

Performance Ponderings Updated

Just updated my "Performance Ponderings" page. It covers my performance analysis papers published over the past 35 yrs. 😳 You may be thinking: Who cares about performance analysis cases that is that dated?

Amazingly, performance analysis (done right) is often not technology-dependent, per se. The right abstraction can remain invariant into perpetuity. For example, my 2025 analysis of the GPT Efficient Computer Frontier (ref. 8 in paper 1) is based partly on my 1989 analysis of virtual memory thrashing in paper 53. Same paradigm; vastly different context.

The connection between the two papers is by no means obvious but, quite striking (not to mention satisfying) when you realize it.

PDQ Online Workshop, May 17-21, 2021

PDQ (Pretty Damn Quick) is a free, open source, performance analyzer available from the Performance Dynamics web site.

All modern computer systems, no matter how complex, can be thought of as a directed graph of individual buffers that hold requests until to be serviced at a shared computational resource, e.g., a CPU or disk. Since a buffer is just a queue, any computer infrastructure, from your laptop up to Facebook.com, can be represented as a directed graph of queues.

The directed arcs or arrows in such a graph correspond to workflows between different queues. In the parlance of queueing theory, a directed graph of queues is called a queueing network model. PDQ is a tool for predicting performance metrics such as, waiting time, throughput, optimal user-load.

Two major benefits of using PDQ are:

1. confirmation that monitored performance metrics have their expected values
2. predict performance for circumstances that lie beyond current measurements

Find out more about the workshop and register today.

CPU Idle Is Not Like White Space

This post seems like it ought to be too trite to write but, I see the following performance gotcha cropping up over and over again.

Under pressure to consolidate resources, usually driven by management and especially regarding processor capacity, there is often an urge to "use up" any idle processor cycles. Idle processor capacity tends to be viewed like it's whitespace on a written page—just begging to be filled up.

The logical equivalent of filling up the "whitespace" is absorbing idle processor capacity by migrating applications that are currently running on other servers and turning those excess servers off or using them for something else.

Hockey Elbow and Other Response Time Injuries

You've heard of tennis elbow. Well, there's a non-sports, performance injury that I like to call hockey elbow. An example of such an "injury" is shown in Figure 1, which appeared in a recent computer performance analysis presentation. It's a reminder of how easy it is to become complacent when doing performance analysis and possibly end up reaching the wrong conclusion.

Figure 1. injured response time performance

Figure 1 is seriously flawed for two reasons:

1. It incorrectly shows the response time curve with a vertical asymptote.
2. It compounds the first error by employing a logarithmic x-axis.

Hotsos Symposium 2012

Time Bandits: How to Analyze Fractal Query Times

Tues, March 6, 2012 @ 2:15 pm

That's the title of my presentation at this year's Hotsos Symposium and no, I won't be trying to make any obscure connections between Terry Gilliam's famous movie and Oracle database products (as interesting as that exercise might be).

Instead, I'll be talking about fractals in time and how they can impact performance—especially Oracle database performance. The responsiveness of your Oracle application can be lost for longer than expected periods of time, ostensibly stolen by time bandits.

Preview Slides (2012). A more detailed explanation of the fractal technique used is now provided in the Guerrilla Data Analytics (GDAT) class: How to Get Beyond Monitoring from Linear Regression to Machine Learning.

Fundamental Performance Metrics

Baron Schwartz invited me to comment on his latest blog post entitled "The four fundamental performance metrics," which I did. Coincidentally, I happened to address this same topic in my presentation at CMG Atlanta last week. As the following slides shows, I claim there are really only 3 fundamental performance metrics (actually 2, if you want to get truly fundamental about it).

Velocity 2010 The Aftermathglow

I was so impressed with Velocity 2009, I really wanted to present something at Velocity 2010.


Thread-limited scalability of memcached
Working with Shanti and Stefan of Oracle (née Sun Microsystems), I was able to accomplish that goal. Our session was rated 92.4%, which is an A+ in anyone's books. Congrats to us and the Velocity organizers and thank you, crowd.

NorCal ORACLE User Group Meeting

The 2010 Winter noCOUG Conference will be held at the CarrAmerica Conference Center in Pleasanton, California, on Thursday, February 11, 2010. Attendance is $50 for non-members. If you're planning to attend, then you will need to RSVP online.

I will be presenting both:

• a Keynote: "Why Are There No Giants?" (9:30 - 10:30) and
  
• a Technical Session: “Performance Analysis for Those Who Can't Wait” (beginner's level, 11:00 - Noon)

Last 2009 Guerrilla Class Next Week

Good news! You can still pile into the last Guerrilla Capacity Planning class for 2009 at the Early Bird rate. Since this class will be professionally videotaped for later distribution on the web, the more the merrier. It's also your chance to be digitally immortalized.


As usual, it will be held at our lovely Larkspur Landing location. Click on the image for booking information.

Registered attendees please bring your laptops, as course materials will only be provided on CD or flash drive, this time. We will be distributing free notepads so you can also take hand-written notes. The venue also has free Wi-Fi to the internet.

Googling Google + Linux

Honorary Guerrilla alumnus, GB, sent me a link to "How Google uses Linux" which, although it provides an interesting view inside The Goog's datacenter management, looks like it's supposed to be available only to LWN subscribers:

"The following subscription-only content has been made available to you by an LWN subscriber." Eh? 

Not wishing to let any cats out of their subscription bag, I checked with the editor and he said it's ok to blog the link.

Hadoop, MAA, ML, MR and Performance Data

Over the past few months, I've been attending a series of talks on machine learning (ML), sponsored by ACM.org at the NASA Ames Research Center, with an eye to applying such things to gobs of computer performance data. Two pieces of technology that kept cropping up were Google MapReduce and Apache Hadoop.

Final Guerrilla Class for 2009 in November

Seats are still available for the final Guerrilla Capacity Planning class of 2009 during November 16-20. All classes are held at our Larkspur Landing location. All 5 days of this class will be professionally videotaped for later online distribution. So, if you want to be digitally immortalized, better get on it.


(Click on the image for details)

New Performance Papers from VMware

Two new performance whitepapers from VMware:

1. VMware vSphere 4: The CPU Scheduler in VMware ESX 4
   
2. Understanding Memory Resource Management in VMware ESX Server:
   

Both apply controlled measurements ("Experimental Environment"), as described in my latest Linux Technical Review article.

Performance und Virtualisierung

Autor: Neil J. Gunther
Erschienen: 15.09.2009
Umfang: 13 Seiten

Woran denkt man, wenn man den Begriff Virtualisierung hört? An einen Hypervisor wie Citrix XenServer oder den ESX-Server von VMware? Oder an virtualisierte Services wie beim Cloud Computing? Oder an Multicore-CPUs mit Hyperthreading, die virtuelle Prozessoren ermöglichen? Am besten betrachtet man all diese Erscheinungsformen von Virtualisierung nicht isoliert, sondern als Teile eines einzigen Performance-Management-Puzzles. Dieser Beitrag erklärt wieso und er unterstreicht, wie wichtig es ist, durch kontrollierte Performance-Messungen Daten zu sammeln.

"Virtualization in the Enterprise from the Performance Management Perspective"

When you see the word virtualization, what do you think of? Hypervisors like Citrix XenServer or VMware ESX? Perhaps you thought of virtualized services like cloud computing? What about hyperthreaded multicores that facilitate virtual processors? Rather than thinking of all these forms of virtualization as being completely different from one another, this article explains why it's better to think of them as being pieces of the same performance management puzzle.The importance of doing controlled performance measurements is also emphasized.

Linux Technical Review

Starbucks Discovers Performance Analysis!

According to the WSJ, Starbucks "vice president of lean" (and apparently mean), has discovered performance analysis.

Heeellooooo! That would be The Principles of Scientific Management, developed by Frederick Winslow Taylor almost a century ago. Of course, it's uncool to be a prophet in your own land, so more notice was eventually taken in Japan then the USA, after WW-II. Baristas will probably be less than bullish on it, but they can take heart that this genius idea by the VP of Lean is totally pre-Toyota.

August Guerrilla Class: Using R for Performance Analysis

Registrations are still open for the Guerrilla Data Analysis Techniques (GDAT) class being held August 10-14, 2009. The focus will be on using R and the new release of PDQ-R for performance analysis and capacity planning.

All Guerrilla classes are held at our Larkspur Landing location in Pleasanton, California; a 45-minute BART ride to downtown San Francisco.


(Click on the image for details)
For those of you coming from international locations, here is a table of currency EXCHANGE rates. We look forward to seeing all of you in August!

WolframAlpha Performance Degradation

Surprise, surprise! After the big wind-up, it turned out that WolframAlpha wasn't really ready for prime time. In an LA Times interview today, Stephen Wolfram, the creator of the site -- five years in the making -- sheepishly explained that a large-scale traffic simulation test had failed. Oops!

Performance Short Course in Switzerland

On June 25 and 26 2009, I will be presenting a 2-day short course on performance analysis and capacity management at Trivadis AG in Zürich, Switzerland.



This class is especially accessible if you are located in central Europe. Since it will come hot on the heels of the TrivadisOPEN conference (23.-24. Juni 2009), it should also be of particular interest if you are responsible for ORACLE database performance management.

I Really Don’t Know Clouds at All (video)

As the well-known cloud-architect, Joni Mitchell, said so presciently:

"I’ve looked at clouds from both sides now
From up and down, and still somehow
It’s cloud illusions I recall
I really don’t know clouds at all”

Or, as Larry Ellison put it more succinctly, "What The Hell Is Cloud Computing?"

Like all things Web 2.0, there's an overabundance of fascination with what can be done vs. how fast it can be done or how many things can be done, before the system might fail to scale.