By: Jenifer Hopper
This article discusses some basic XML tuning tips for PowerKVM guests. It helps new users get started with editing guest XML definitions, and walks through some simple tuning examples.
The article covers various options to tune the guest disk, network, cpu, and memory. It also includes some example guest resource pinning configurations for different scenarios. Applying these tips may help improve application performance by ensuring your guest is configured properly and optimized for... [More]
By: Jenifer Hopper
This article explains an example method to tune a full-system PowerKVM guest to achieve CPU and memory performance that is very close to non-virtualized speeds, demonstrating very low KVM overhead on a POWER8 system. It also provides some common tuning tips for running SPECjbb2005 and the STREAM memory bandwidth workload on POWER8 systems.
The example tutorial starts by measuring non-virtualized performance to provide a system baseline (non-virtualized mode is currently a technical... [More]
By: Jenifer Hopper
Are you interested in better understanding memory access performance? A new article, Untangling memory access measurements - memory latency explains how to use an example benchmark called lat_mem_rd to measure memory read latency on IBM® Power Systems™ servers running Linux.
This article takes a practical approach to measuring memory latency performance, from understanding initial results to moving on to examining the effects of more... [More]
By: Steve Dobbelstein.
On February 22, 2013, IBM® published a new SPECjEnterprise®2010 result on a two socket system. The result was achieved on the new IBM PowerLinux™ 7R2 system using IBM WebSphere® Application Server v8.5 and IBM DB2® 10.1 running on Red Hat® Enterprise Linux® release 6.4. The Linux Technology Center (LTC) team, the WebSphere team, the Java team, and the DB2 team all worked together to analyze and tune the performance of the... [More]
By: Maynard Johnson and Beth Taylor. Finding performance bottlenecks in applications that you develop can be a daunting task. But with the right tools and a little guidance, it's easier than you might think. OProfile is a performance analysis tool set for Linux systems. A new collection of topics has been published in the Linux for IBM Systems Information Center to help application developers get started with OProfile on Power Systems™ servers running Linux. Getting started with OProfile on PowerLinux introduces the new operf... [More]
By: Anirban Chatterjee.
month, the PowerLinux team is announcing the biggest technology change in PowerLinux servers
since we launched, with the availability of our POWER7+ chips on the platform.
POWER7+ is more than just a speed bump on our POWER7
processors. Our hardware teams have
worked hard to increase the flexibility of the platform, bringing
balanced performance increases while keeping other factors like energy
consumption at bay. Some examples:
doubled the memory capacity in... [More]
zswap" is discussed, with some initial performance data provided to demonstrate the potential benefits for a system (partition or guest) which has constrained memory and is beginning to swap memory pages to disk. The technique improves the throughput of a system, while significantly reducing the disk I/O activity normally associated with page swapping. We also explore how zswap works in conjunction with the new compression accelerator feature of the POWER7+ processor to potentially improve the system throughput even more... [More]
By: Beth Taylor and Walt Madden. Several previous blog posts have told of the
advantages of IBM ®
Advance Toolchain for PowerLinux for application performance analysis on IBM
Power Systems ™
servers. Likewise, you've heard about
IBM Software Development Kit for PowerLinux ™ , which combines C/C++ source
development with the Advance Toolchain and classic Linux debugging and
performance analysis tools like OProfile. Recently, the IBM InfoSphere Streams development
team has had the positive experience to give credit to these claims... [More]
By: Jenifer Hopper. More details on CPU utilization issues
I recently posted about a RHEL6.3 kernel update that resolves a CPU utilization bug in this blog . Since then I have received a few questions asking for more details, so I want to share those here. Q: The problem was in /proc/stat? What was the issue? A: Yes, there was a bug that caused incorrect idle and iowait values to be displayed in /proc/stat. The main issue was a change that caused an incorrect divisor to be used (msec vs. usec). Q: Do I need to update my profiling... [More]
By: Jenifer Hopper.
Fixing CPU utilization metrics on RHEL 6.3
As reported earlier in a blog post , the standard RHEL 6.3 kernel has issues with correctly calculating CPU utilization values .
(For more insights into the fix below, see a different blog post )
** Note: The specific zstream kernel version mentioned in this article was the most recent at the time of publication. Newer RHEL 6.3 zstream kernel releases should contain this... [More]
By: Carlos Seo. The IBM Advance Toolchain for PowerLinux is a set of open source development tools and runtime libraries which allows users to take leading edge advantage of IBM's latest POWER hardware features on Linux. A new update release is now available, and it features: Bug fixes for DFP in GCC. Fix to address over counting user context lost samples in Oprofile. GDB now displays correctly the vperm instruction. Time zone for the Advance Toolchain is now automatically set to the system's time zone. New advance-toolchain-at5.0-selinux rpm,... [More]
By: Bill Buros. If you've updated to the most recent RHEL 6.3, you might be seeing issues with CPU utilization being reported to the end users.
# uname -r 2.6.32-279.el6.ppc64 With the kernel here, if you run "top" on an idle system, it may report clearly inaccurate CPU utilization metrics, as in the idle system below. 66% kernel time on an idle system is not accurate.
# top top - 16:05:04 up 1 day, 39 min, 2 users, load average: 0.00, 0.00, 0.00 Tasks: 1167 total, 1 running, 1166 sleeping, 0 stopped, 0... [More]
By: Carlos Seo. The IBM Advance Toolchain for PowerLinux is a set of open source development tools and runtime libraries which allows users to take leading edge advantage of IBM's latest POWER hardware features on Linux. A new major release is now available, and it features: New base toolchain, based on gcc-4.7.2 and glibc-2.16 Supported on SLES 11 and RHEL 6 only (and their respective Service Packs and Updates) Optimized libraries for POWER7 only gcc now defaults to -mcpu=power6 -mtune=power7 Oprofile now supports non-root single... [More]
By: Steve Champagne. For information about performance tuning on your PowerLinux system, be sure to see the A Tuning Guide for PowerLinux section of Performance Rocks - Best Practices . I added three new sections there today:
Tuning Guide: Compilers and Optimization Tools for C/C++/Fortran
Tuning Guide: Empirical Performance Analysis using the IBM SDK for PowerLinux
Tuning Guide: Deeper Empirical Analysis for improving performance
By: Carlos Seo. The IBM Advance Toolchain for PowerLinux is a set of open source development tools and runtime libraries which allows users to take leading edge advantage of IBM's latest POWER hardware features on Linux. A new release is now available, and it features: Performance improvements for tcmalloc Bug fixes for DFP support in Valgrind For download links, more information and documentation, please refer to our official documentation page . Please let us know if you have any questions about this release.
By: Carlos Seo. The IBM Advance Toolchain for PowerLinux is a set of open source development tools and runtime libraries which allows users to take leading edge advantage of IBM's latest POWER hardware features on Linux. A new release is now available, and it features: Important bug fixes in libstdc++ Added support for DFP (decimal floating point) for Power in valgrind Updated OpenSSL to 1.0.1c For download links, more information and documentation, please refer to our official documentation page . Please let us know if you have any... [More]
New IBM XL compiler versions now available!
By: Bill Buros.
IBM has released the IBM XL C/C++ Version 12.1 and IBM XL Fortran V14.1 products for use on PowerLinux systems.
IBM XL C/C++: http://www-01.ibm.com/software/awdtools/xlcpp/linux/
IBM XL Fortran: http://www-01.ibm.com/software/awdtools/fortran/xlfortran/linux/
Over on developerWorks, there are two good articles on "what's new" with these new versions.
What's new with IBM XL C/C++ for AIX and Linux,... [More]
Performance Projections vs "Hope for the Best" By: Bill Buros. Here's a quick introduction to the notion of understanding what you're trying to do when you are looking for performance improvements. Over the last month or two, we have been focused on several engagements where we are helping to improve an application's performance on Linux. Being in the Linux Technology Center, we focus on Linux itself, the tools, commands, products, and post-processing analysis of the results. So while we often deal first with Power systems, many of... [More]
Need Java 7? We got Java 7. By: Bill Buros. Last year we posted that the IBM Java 7 was in open beta mode, but along the way we neglected to post the news that the IBM Java 7 kits are now fully available across a number of platforms and operating systems. By now, this is relatively older news, IBM Java 7 was announced back in September 2011, but it's always good to remind people and teams that it's available. This latest IBM Java is available on Power systems and across the RHEL and SLES distros available for Power. We use the latest... [More]
By: Bill Buros. Continuing our journey into benchmarks, we recently were working on the SPECcpu2006 set of benchmarks again, and returned to look at some of the dependent products which we build and run with. One of the products which we link with on Power Linux is MicroQuil's Smartheap library. This is a run-time library which can be purchased from MicroQuil. One of the benchmark components of the SPECcpu2006 suite - xalancbmk - is a classic example of a questionable choice as a system and compiler measurement benchmark. The... [More]
The common standard benchmarks By: Bill Buros. After we have a new Power7 system installed and configured, we generally will run a set of performance benchmarks on the system to confirm that it's running things as we expect it to. In a performance lab like ours, we have the luxury of access to SPEC.org benchmarks, the latest IBM XL C/C++ and Fortran Compilers, the latest gcc-based Advance Toolchain libraries, and the full suite of performance tools and profilers installed on our systems. On a new system, we will regularly install,... [More]
By: Bill Buros. This morning we got into a good discussion on what simple things that we check on a new system or partition for Power Linux.
The list was easy. How many cores? what SMT mode are the cores running in? how fast are the cores running? how much memory is available? how is the memory balanced? and is any of the memory tied up in Hugepages?
So we wrote a quick script here to get that information and thought we'd post that here. Edit'ed Aug 3rd 2012: See a new article " Setup and understand your system " for a more... [More]
By: Bill Buros. I thought this would be a relatively trivial exercise, but as with any good technology answer, it depends. It depends on your server, how it's controlled, and the distro releases you have. In this case, I have a Power7 server connected to an HMC with RHEL 6.1 installed on the server which is connected to a previously enabled RHEL 6.1 yum repo. NOTE: That "enabled RHEL 6 yum repo" is an important assumption. You can check that you have that enabled with the command # yum repolist and look for the base... [More]
By: Bill Buros. Recently, the IBM SDK for Linux on Power released another beta update of the environment for developing, debugging, and doing performance analysis of programs running on Power systems. On a regular basis, people ask about the SDK and wonder "So... what exactly can this do?" . Being a little tired of creating more and more wiki pages, I'm hoping that the video approach might be more interesting and quickly informative (not to mention it provided a nice tangent on the few days before the Thanksgiving break). ... [More]
By: Bill Buros. In the continuing journey of performance improvements with GCC, numerous development and performance teams recently hit an interesting milestone with results taking advantage of GCC compilers. The bottom-line difference between similar publishes of SPECint_rate_base2006 has broken the 10% difference milestone on Base measurements. These results are taking advantage of GCC-4.6.1-ibm-r176948 build. The bottom-line difference is calculated by taking the scores of 12 different programs and doing something called a "... [More]
Java Java Java! By: Bill Buros. If you're interested in the latest Java technology, IBM is running an open beta program for IBM SDK for Java™ 7 . In the Beta, there are a number of new technologies, new approaches, improvements, and updates. In the Linux Technology Center, we're busy updating the Java Performance on POWER7 article with new recommended tunings and optimizations, getting experience with the Beta release and the Java 7 update, and of course providing feedback to the development teams.
In the coming days, we'll be... [More]
By: Bill Buros.
Java based applications and workloads are pervasive in the server space. Nicely, IBM provides Power-tuned Java engines for the operating systems which run on Power servers. Easy to download . Easy to install. Easy to leverage. This allows product teams around the world to leverage the best of Java with the best of Power7 servers to deliver applications optimized for Power. IBM teams regularly provide the latest Java updates,... [More]
By: Jessica Erber-stark. Check out the Linux Information Center for new information about Improving performance with Advance Toolchain 4.0 About the Advance Toolchain : The Advance Toolchain provides early and easy access to
libraries and the latest compiler technologies for Linux distributions. Over time, these libraries
and latest compiler technologies are integrated into the shipping
distributions. However, the Advance Toolchain contains the latest
tested and supported GNU Compiler Collection (GCC) compiler versions,
tailored for... [More]
By: Bill Buros. Continuing our theme of leveraging gcc for performance based workloads, here we point to a couple of recent Linpack results from the Top500 web site. The Top500 site tracks the results of Linpack runs from small single standalone servers all of the way up through the Top 500 supercomputers in the world. Naturally, the smaller results are buried in a very big table somewhere on the site, but the Top500 entries are listed separately. What’s noteworthy in the two results below is that "gcc" was leveraged to build... [More]
Last week a new SAP Sales and Distribution (SD) Standard Application Benchmark result was published on the SAP benchmark site ( here ). The result was produced with SLES 11 sp1 running on an IBM Power 730 12-core system. What's particularly cool for us is the result was produced with gcc 4.3.4 as shipped with the SLES 11 distro. For more information on general SAP tunings, an IBM InfoCenter Blueprint paper was published which explains how to tune an SAP implementation on Linux on Power. The article describes common system tunings, as... [More]