Messages in this thread | | | Subject | Re: [PATCH 2/2] perf_counter: optimize context switch between identical inherited contexts | From | Peter Zijlstra <> | Date | Fri, 22 May 2009 11:42:12 +0200 |
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On Fri, 2009-05-22 at 11:22 +0200, Peter Zijlstra wrote: > On Fri, 2009-05-22 at 14:27 +1000, Paul Mackerras wrote: > > > > -----Unmodified----- With this patch series > > Counters: none 2 HW 4H+4S none 2 HW 4H+4S > > > > 2 processes: > > Average 3.44 6.45 11.24 3.12 3.39 3.60 > > St dev 0.04 0.04 0.13 0.05 0.17 0.19 > > > > 8 processes: > > Average 6.45 8.79 14.00 5.57 6.23 7.57 > > St dev 1.27 1.04 0.88 1.42 1.46 1.42 > > > > 32 processes: > > Average 5.56 8.43 13.78 5.28 5.55 7.15 > > St dev 0.41 0.47 0.53 0.54 0.57 0.81 > > Any clues as to why the time is still dependent on the number of > counters in the context? The approach seems to be O(1) in that it > does a simple counter context swap on sched_out and nothing on sched_in.
Ah, should I read this as 'n' lmbench instances on a single cpu? So that we get multiple inheritance sets mixed and have to switch between them?
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