volanoMark 12% regression with 2.6.25-rc6

From: Zhang, Yanmin
Date: Tue Mar 18 2008 - 05:16:18 EST


Comparing with 2.6.25-rc5, volanoMark has 12% regression with 2.6.25-rc6
on my 8-core stoakley.


Bisect tracked it down to:

e22ecef1d2658ba54ed7d3fdb5d60829fb434c23 is first bad commit
commit e22ecef1d2658ba54ed7d3fdb5d60829fb434c23
Author: Ingo Molnar <mingo@xxxxxxx>
Date: Fri Mar 14 22:16:08 2008 +0100

sched: fix fair sleepers

Fair sleepers need to scale their latency target down by runqueue
weight. Otherwise busy systems will gain ever larger sleep bonus.

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>


In the patch, vruntime -= calc_delta_fair(sysctl_sched_latency, &cfs_rq->load).

Should we call __sched_period to get the first parameter of calc_delta_fair in case
there are more than 5 tasks in the runqueue?

-yanmin


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