Messages in this thread | | | Subject | Re: hackbench regression with 2.6.26-rc2 on tulsa machine | From | Mike Galbraith <> | Date | Tue, 20 May 2008 11:22:32 +0200 |
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On Tue, 2008-05-20 at 16:09 +0800, Zhang, Yanmin wrote: > Comparing with 2.6.26-rc1, hackbench has about 30% regression with 2.6.26-rc2 on my tulsa machine > which is a netburst architecure hyper-threading x86_64. > > Command line to test: #hackbench 100 process 2000 > > With 2.6.26-rc1, it takes 30 seconds. But with 2.6.26-rc2/rc3, it takes 40 seconds. > > Bisect located below patch: > 46151122e0a2e80e5a6b2889f595e371fe2b600d is first bad commit > commit 46151122e0a2e80e5a6b2889f595e371fe2b600d > Author: Mike Galbraith <efault@gmx.de> > Date: Thu May 8 17:00:42 2008 +0200 > > sched: fix weight calculations > > The conversion between virtual and real time is as follows: > > dvt = rw/w * dt <=> dt = w/rw * dvt > > Since we want the fair sleeper granularity to be in real time, we actually > need to do: > > dvt = - rw/w * l > > > > The bisect steps look stable. > > On my core architecure machines(stoakley and tigerton), I do see improvement instead of regression, > like result from 31 seconds down to 28 seconds. > > I'm not sure if hyper-threading need more cares in this situation.
Oh joy. I'll update my poor old P4 and see what I can duplicate this.
Do you still have group scheduling enabled? If so, can you turn it off and try again? (when in doubt, grasp at any straw within reach;)
-Mike
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