One of the interesting things about new POWER7 hardware and AIX 7 is the integration between them, which is one of the key selling points: IBM's investment in both hardware and the OS contribute to its impressive performance gains.
In the case of POWER7, customers running AIX 7 will obviously gain the most benefits, but if there's one thing that's true about IBM, the company keeps the door open for lagging customers for a long time, sometimes years. And sometimes customers do lag -- or have some workloads that lag behind.
It's this point that I want to highlight from Jay Kruemcke's AIX 7 - The Future of UNIX presentation, presented today (and available soon as a recorded event). Kruemcke is the AIX program director for IBM, and while he jammed a wide range of AIX 7 and POWER7 information into less than an hour, POWER7 and AIX 7 may become the key catalysts that help IBM customers on older releases sit up and begin their upgrades.
For example, to help its customers along, POWER7 lets you run LPARs in one of three modes -- POWER7, POWER6, or POWER6+. The modes, then, reflect the capabilities inherent in each generation of POWER processor. When a POWER7-based Power Systems server is running in what IBM calls POWER7 mode, you can run both AIX 7 and AIX 6 . . . but what about AIX 5.3?
To run AIX 5.3, you would run in POWER6 or POWER6+ modes. While the ability to run AIX 5.3 on new hardware provides a range of benefits, Kruemcke gave an interesting example of how IBM can squeak out better performance for those customers also running AIX 6 or AIX 7 -- to the tune of a 17 percent performance gain.
"The big difference between AIX 5.3 running on a POWER7 system and AIX 6 or AIX 7 is that POWER7 mode allows four-thread SMT, or four simultaneously threads executing on each core at any instant in time," Kruemcke explains. "And we call this capability IntelliThreads because the system will automatically use the number of threads that best fits your workload."
So, while AIX 6 and AIX 7 can utilize four threads per physical core, AIX 5.3 users are limited to two threads per core. Then there's the feature IBM calls Affinity.
When you allocate a partition, you create a certain amount of memory allocated to a physical location in the system itself. If you're using MicroPartitions or shared processor pools, Kruemcke says, the processor that actually services a thread at any particular instant might be any one of the processors in the system. "What we do inside the hypervisor, with the assistance of AIX providing some hints, we try to pick the core that's closest to the physical location in memory. We call that Affinity," Kruemcke explains.
While IBM has been working on Affinity since AIX 5.3 on POWER5, IBM built in some new enablement into the POWER7 chip itself to improve Affinity, which is only available when running in POWER7 mode.
"These two things -- the four-thread SMT and the better Affinity -- means that if you're running a workload in a POWER7 mode, you can see up to 17 percent better performance than you would running the same workload in a POWER6 or POWER6+ mode. So there's a clear definition now for you to move up to AIX 6 or AIX 7 when you're running on a POWER7," Kruemcke says.
So Much More
There is, of course, so much more packed into the webcast, including more detail about IBM's AIX Workload Partitions, and the new AIX 5.2 Workload Partitions for AIX 7, which brings us back around to IBM's leaving the door open for lagging customers. With AIX 5.2 Workload Partitions for AIX 7, customers can migrate their old AIX 5.2 workloads to POWER7. It's not free, but it's hard to argue that it's not wicked cool. With it, you can run really old workloads on brand spanking new hardware on top of AIX 7.
Basically, you back up your existing legacy AIX 5.2 environment and restore it to an AIX 7 WPAR, and your old applications running on AIX 5.2 continue to run in an AIX 5.2 environment with AIX 5.2 libraries. Interested in learning more? Obviously, listening to the recording of the AIX 7 - The Future of UNIX presentation is a good idea, but you can also learn more at IBM's AIX 5.2 Workload partitions for AIX 7 site.
And the rest of the Power of AIX - 2010 Fall Webcast Series?
Here's the upcoming live sessions and times: