Re: [patch] CFS scheduler, -v12

Siddha, Suresh B
2007-05-24T16:49:16Z

On Thu, May 24, 2007 at 12:43:58AM -0700, Peter Williams wrote:
>Peter Williams wrote:
>> The relevant code, find_busiest_group() and find_busiest_queue(), has a
>> lot of code that is ifdefed by CONFIG_SCHED_MC and CONFIG_SCHED_SMT and,
>> as these macros were defined in the kernels I was testing with, I built
>> a kernel with these macros undefined and reran my tests. The
>> problems/anomalies were not present in 10 consecutive tests on this new
>> kernel. Even better on the few occasions that a 3/1 split did occur it
>> was quickly corrected to 2/2 and top was reporting approx 49% of CPU for
>> all spinners throughout each of the ten tests.
>>
>> So all that is required now is an analysis of the code inside the ifdefs
>> to see why it is causing a problem.
>
>
>Further testing indicates that CONFIG_SCHED_MC is not implicated and
>it's CONFIG_SCHED_SMT that's causing the problem. This rules out the
>code in find_busiest_group() as it is common to both macros.
>
>I think this makes the scheduling domain parameter values the most
>likely cause of the problem. I'm not very familiar with this code so
>I've added those who've modified this code in the last year or
>so to the
>address of this e-mail.

What platform is this? I remember you mentioned its a 2 cpu box. Is it
dual core or dual package or one with HT?

thanks,
suresh