OS2 World.Com Forum

Subject  :  ACPI and Hyperthreading
Author  :  Blonde Guy
Date  :  05 Nov, 2006 on 16:19
If you have the ACPI beta and a hyperthreading CPU, then you should be able to run eComStation Pro (the SMP kernel and doscalls1.dll, etc) to really get the effect of two processors.

We did so at the last BayWarp meeting, and while we did see some evidence of two processors, we ran out of time before we got to any conclusions.

Does anyone else have some experience with this, and how would you best demonstrate that both CPUs are working?


Expert Consulting for OS/2 and eComStation

Subject  :  Re:ACPI and Hyperthreading
Author  :  Kim
Date  :  06 Nov, 2006 on 12:06
Well, earlier when I had a ABIT BP6 board with two Celeron CPU's 366@550MHz together with WSFEB it was quite easy; by checking the CPU meeter and start an application that loads the CPU 100%. In my case I used to test with SETI clients but don't know what current status is with the SETI client for OS2.

Subject  :  Re:ACPI and Hyperthreading
Author  :  Sebadoh sys3175@optonline.net
Date  :  06 Nov, 2006 on 17:25
My problem with this discussion is there is a big difference between an Intel Hyper threading CPU and the newer round of Dual Core cpus. The dual core cpu's actually have two cores, running at the same speed, while the hyper thread cpu's have a simulated second core running at a lower clock rate.

You should see a decent performance improvement with a dual core processor, the hyper threading processors usually show little to no improvement, although you might find slightly better wps response under high system usage.

Seti is a great way of demonstrating assuming that seti is a multi threaded app (i believe it is).


Subject  :  Re:ACPI and Hyperthreading
Author  :  obiwan
Date  :  06 Nov, 2006 on 19:32
I think Sebadoh is right. Even on other platforms I haven't seen that hyperthreading CPU's give any explicit indication anywhere that there is an additional CPU.

Subject  :  Re:ACPI and Hyperthreading
Author  :  davidfor
Date  :  07 Nov, 2006 on 02:03
Unfortunately, I do not have hyperthreading machine I can test OS/2 on. Or an SMP licence for that matter. But, I have been doing stuff under Windows.

Windows 2003 server shows two CPUs when run on a machine with Hyperthreading. And turning it on does help. My job for the last 18 months has been testing software we develop. This is a development tool that generates source code from a model definition stored in SQLServer. There is a noticeable performance improvement when Hyperthreading is on compared to when it is not on. From memory it was better than 25% faster. This was happening because Windows could run SQLServer and our application on the real and virtual CPU and the total context swapping was less than when there was only the real CPU.

The interesting difference came with Pentium D machines. These have two cores and hyperthreading. On these machines, it was better to turn hyperthreading off. The problem was that Windows 2003 cannot tell the difference between the real and virtual processors. It would allocate SQLServer and our process to the real and virtual processors of the same physical processor. Turning off hyperthreading on these machines was getting us close to halving the single processor time.

OS/2 should benefit from hyperthreading. Because of the way that hyperthreading works, I would expect to see more improvement in a multi-threaded application than when running multiple single threaded processes. And OS/2 has always been good at multi-threading. Unfortunately, I can't think of a good test application. The old SETI@Home was a single thread application. I don't know about the BOINC version as I don't run it.

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David


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