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SubjectRe: [revert] mysql+oltp regression
Gregory Haskins wrote:
> Ingo Molnar wrote:
>> * Gregory Haskins <ghaskins@novell.com> wrote:
>>
>>
>>>>> Speaking of this: Another patch I submitted to you Ingo (had to do
>>>>> with updating the load_weight inside task_setprio) seems to also
>>>>> have this phenomenon: e.g. its technically correct but further
>>>>> testing has revealed negative repercussions elsewhere. So please
>>>>> ignore that patch (or revert if you already pulled in, but I don't
>>>>> think you have). Ill try to look into this issue as well.
>>>>>
>>>> ok, under which thread/subject is that? Not queued in tip/sched/*
>>>> yet, correct?
>>>>
>>> Here is the original thread:
>>>
>>> http://lkml.org/lkml/2008/7/3/416
>>>
>>> I do not believe you have queued it anywhere (public anyway) yet.
>>>
>>> Note I have already invalidated 1/2, and now I am retracting 2/2 as
>>> well. (1/2 is actually a bogus patch, 2/2 is "technically correct"
>>> but causes ripples in the load balancer that need to be sorted out
>>> first.
>>>
>>
>> ok, thanks. I'm curious, what are those ripple effects? Stability or
>> performance?
>>
>
> Performance. I found it while working on my pi series (which fyi I
> should have a v2 refresh for soon, probably today...i am hoping to get
> some review feedback from you on that as well, time permitting of
> course ;).
>
> Basically the behavior I was observing was that kernel builds via
> distcc would cluster all the cc1 jobs on a single core. At first I
> thought my pi-series was screwed up, but then I realized I had applied
> the patch referenced above earlier in my development tree, and
> removing it allowed pi to work fine.
>
> I found the problem with in once boot cycle with ftrace (thanks Steve!).

Hmm..Im not sure what went wrong between brain and hand above, but of
course I meant to say ".. within one boot cycle ..", not "with in
once". Heh.


> Basically newidle balancing was always returning "no imbalance" even
> though I had 32 cc1 threads on 1 core, and 3 idle cores. Clearly not
> correct! So I think that by adjusting the load up, we throw off the
> hysteresis built into the load averages and cause the system to
> incorrectly think it's balanced. TBD.
>
> -Greg
>
>
>> Ingo
>>
>
>


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