Balbir Singh wrote:
> Ingo Molnar wrote:
>> * Balbir Singh <[EMAIL PROTECTED]> wrote:
>>
>>> If you insist that sched_yield() is bad, I might agree, but how does
>>> my patch make things worse. [...]
>> it puts new instructions into the hotpath.
>>
>>> [...] In my benchmarks, it has helped the sched_yield case, why is
>>> that bad? [...]
>> I had the same cache for the rightmost task in earlier CFS (it's a
>> really obvious thing) but removed it. It wasnt a bad idea, but it hurt
>> the fastpath hence i removed it. Algorithms and implementations are a
>> constant balancing act.
>
> This is more convincing, was the code ever in git? How did you measure the
> overhead? What are your plans for reports with regressions where
> kernel.compat_sched_yield is set to 1?
>
Ingo,
I was looking through nptl/sysdeps/unix/sysv/linux/pthread_yield.c in the glibc
sources and it looks like pthread_yield() calls sched_yield(). Applications
using compat_sched_yield and pthread_yield() are also going to be impacted.
I searched for pthread_yield and sched_yield using google codesearch to look at
the applications that use these routines, the search list is too big for me to
mark applications as candidates for potential improvement.
--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
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