Messages in this thread | | | Subject | Re: VolanoMark regression with 2.6.27-rc1 | From | Peter Zijlstra <> | Date | Fri, 08 Aug 2008 09:30:05 +0200 |
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On Tue, 2030-08-06 at 11:26 +0800, Zhang, Yanmin wrote: > On Mon, 2008-08-04 at 09:12 +0200, Peter Zijlstra wrote: > > On Mon, 2008-08-04 at 12:35 +0530, Dhaval Giani wrote: > > > On Mon, Aug 04, 2008 at 08:26:11AM +0200, Peter Zijlstra wrote: > > > > On Mon, 2008-08-04 at 11:23 +0530, Dhaval Giani wrote: > > > > > > > > > Peter, vatsa, any ideas? > > > > > > > > --- > > > > > > > > Revert: > > > > a7be37ac8e1565e00880531f4e2aff421a21c803 sched: revert the revert of: weight calculations > > > > c9c294a630e28eec5f2865f028ecfc58d45c0a5a sched: fix calc_delta_asym() > > > > ced8aa16e1db55c33c507174c1b1f9e107445865 sched: fix calc_delta_asym, #2 > > > > > > > > > > Did we not fix those? :) > > > > Works for me,.. just guessing here. > I did more investigation on 16-core tigerton. > > Firstly, let's focus on CONFIG_GROUP_SCHED=n. With 2.6.26, the result > has little difference > between with and without CONFIG_GROUP_SCHED. > > 1) I tried different sched_features and found AFFINE_WAKEUPS has big > impact on volanoMark. Other > features have little impact. > > 2) With kernel 2.6.26, if disabling AFFINE_WAKEUPS, the result is > 260000; if enabling AFFINE_WAKEUPS, > the result is 515000, so the improvement caused by AFFINE_WAKEUPS is > about 100%. With kernel 2.6.27-rc1, > the improvement is only about 25%. > > 3) I turned on CONFIG_SCHETSTATS in kernel and collect > ttwu_move_affine. Mostly, collect ttwu_move_affine, > then recollect it after 30 seconds and calculate the difference. With > 2.6.26, I got below data:
<snip data>
> So with kernel 2.6.27-rc1, the successful wakeup_affine is about > double of the one of 2.6.27-rc1 > on domain 0, but about 10 times on domain 1. That means more tasks are > woken up on waker cpus. > > Does that mean it doesn't follow cache-hot checking?
I'm a bit puzzled, but you're right - I too noticed that volanomark is _very_ sensitive to affine wakeups.
I'll try and find what changed in that code for GROUP=n.
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