Messages in this thread | | | Subject | [patch 0/12] sched: fastpath cycle recovery | From | Mike Galbraith <> | Date | Thu, 11 Mar 2010 10:49:10 +0100 |
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Hi Peter,
The following patchlets take a pinned pipe-test context switch frequency in tip from 663KHZ to 694KHZ, and an unpinned instance from 450KHz to 540KHz. With these applied to tip.today, I have zero 31-12->today regressions, and even some modest progressions.
The biggest difference is made by the first patch. We have a problem with nohz when waking cross-cpu, which given select_idle_sibling(), we do quite a bit. In testing netperf TCP_RR, hitting nohz code on every micro-idle was eating ~10% of throughput, making cross-cpu wakeup a loser. These patchlets combined turned netperf TCP_RR cross-cpu vs affine from big loser into a winner.
All of these are trivial, mostly axe murder, but cycles add up.
-Mike
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