Looking for Huge Performance Gains? Virtualize With Red Hat Enterprise Linux 5

September 21, 2007

by RHEL5 Team

Not many people think of virtualization as a way to make applications run faster. In fact, the general assumption is that things are likely to be a little slower, hopefully not too much, but that the other advantages easily outweight the performance drop.

OK, so virtualization does cost some performance. But with the para-virtualization in Red Hat Enterprise Linux 5, we are seeing very small drops. Of course it’s application dependent, but single-digit percentage points seem to be the norm. Given the increased operational flexibility, for most this is absolutely a cost worth bearing. Bottom line: it makes sense to run any Red Hat Enterprise Linux 5 system with paravirtualized guests.

So where’s the performance increase, you ask? It’s in the hardware! But before you cry “foul,” bear with us for a moment. Red Hat and Intel have worked closely for many years and most recently we have collaborated on providing optimized support for Intel’s new Tigerton/Caneland quad-core systems. One of the big advantages of doing this development using the open source collaboration model is that engineers from both companies work really closely together to make things sing. The result is that these systems are supported in Red Hat Enterprise Linux 5.1, which is scheduled for general availability at the end of October 2007, and in tests they are delivering simply stunning performance.

Additionally, Red Hat Enterprise Linux 5.1 will include para-virtualized drivers for use with fully virtualized guests. Initially these will be for Red Hat Enterprise Linux 3, with drivers for non Red Hat operating systems expected to appear in the following months. We think these drivers will deliver another big boost to performance. You may recall that paravirtualization for Red Hat Enterprise Linux 4 was delivered with Update 5.

The net effect of these technologies is that you can take a complete, stable application stack based on Red Hat Enterprise Linux 3, run it as a virtualized guest on a new Caneland system and gain a significant performance boost. Note that Red Hat Enterprise Linux 3 doesn’t support Caneland systems directly, so without virtualization it would be necessary to redeploy your application stack on Red Hat Enterprise Linux 5 before you could enjoy the performance boost – something you may not have the time or resources to do.

And where’s the proof? Red Hat and Intel asked a respected third-party performance testing laboratory – Principled Technologies – to perform some industry-standard benchmarks on these new capabilities. The results can be found here.

You will find great reports for SPECjbb2005, SPECcpu2006 and Linpack. Without going into all the numbers in this blog, the SPECjbb2005 report provides a good taste of the results:

  • A Xeon system running Red Hat Enterprise Linux 3 achieved approximately 210,000 operations/second (4 socket, hyperthreaded, dual core allowing for 16 compute threads).
  • A Caneland system running Red Hat Enterprise Linux 5 achieved approximately 380,000 operations/second (4 socket, quad core also allowing for 16 compute threads).
  • A Red Hat Enterprise Linux 3 virtualized guest running on a Red Hat Enterprise Linux 5 host achieved approximately 340,000 operations/second. So Red Hat Enterprise Linux 3 delivered a performance increase of over 50 percent when running virtualized on the new Caneland system.

Clearly, the newer hardware is playing the major role in the performance boost, but that’s what Moore’s law has always provided. The new twist is that you can enjoy the benefits of Moore’s law without the pain of migrating application stacks to the new system.

So there you have it: old software on new hardware with virtualization equals more performance – with none of the trauma associated with application upgrades and requalification. And virtualization is included in every Red Hat Enterprise Linux system for no additional cost. You know it makes sense!

And one more thing. VMware does not support virtual machine guests with more than four executable threads. Meanwhile, Red Hat Enterprise Linux guests can utilize all the underlying hardware – so a full quad-core, 4-socket system can be virtualized and presented to Red Hat Enterprise Linux 3. Put bluntly, VMware cannot provide a virtual machine guest larger than 1/4 of the new Caneland capacity.

For more information on Red Hat’s virtualization capabilities, see here.

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