Messages in this thread | | | Date | Wed, 18 Mar 2009 16:08:27 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH -tip] cpuacct: Make cpuacct hierarchy walk in cpuacct_charge() safe when rcupreempt is used. |
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On Wed, 18 Mar 2009 10:18:01 +0530 Bharata B Rao <bharata@linux.vnet.ibm.com> wrote: > Looks ok to me, but will wait for experts' comments. > > However, I did a quick measurement of read times with percpu_counter_read() > (no readside lock) and percpu_counter_sum() (readside lock) and I don't > see a major slowdown with percpu_counter_sum(). > > Time taken for 100 reads of cpuacct.stat with 1s delay b/n every read. > percpu_counter_read() - 9845 us > percpu_counter_sum() - 9974 us > Then, almost 1 us overhead per read().....Hmm, seems big (as counter).
Thanks, -Kame
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