Messages in this thread | | | Date | Fri, 6 Nov 2009 09:04:18 +0100 | From | Ingo Molnar <> | Subject | Re: specjbb2005 and aim7 regression with 2.6.32-rc kernels |
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* Zhang, Yanmin <yanmin_zhang@linux.intel.com> wrote:
> Comparing with 2.6.31, specjbb2005 and aim7 have some regressions with > 2.6.32-rc kernels on core2 machines. > > 1) On 4*4 core tigerton: specjbb2005 has about 5% regression. > 2) On 2*4 stoakley: aim7 has about 5% regression. > > On Nehalem, specjbb2005 has about 2%~8% improvement instead of > regression. > > aim7 has much dependency on schedule patameters, such like > sched_latency_ns, sched_min_granularity_ns, and > sched_wakeup_granularity_ns. 2.6.32-rc kernel decreases these > parameter values. I restore them and retest aim7 on stoakley. aim7 > regression becomes about 2% and specjbb2005 regression also becomes > 2%. But on Nehalem, the improvement shrinks.
Which precise 2.6.32-rc commit have you tested?
Since v2.6.32-rc6 Linus's tree has this one too:
f685cea: sched: Strengthen buddies and mitigate buddy induced latencies
Which should improve things a bit. For 2.6.33 we have queued up these two in -tip:
a1f84a3: sched: Check for an idle shared cache in select_task_rq_fair() 1b9508f: sched: Rate-limit newidle
If any of them fixes a performance regression we could still merge them into 2.6.32 as well.
Ingo
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