Messages in this thread |  | | | Date | Thu, 27 May 2010 13:54:46 -0700 | | Subject | Re: [PATCH] perf: implement recording/reporting per-cpu samples | | From | Arun Sharma <> |
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On Thu, May 27, 2010 at 11:41 AM, Arnaldo Carvalho de Melo <acme@ghostprotocols.net> wrote: > Em Wed, May 05, 2010 at 11:16:12AM -0700, Arun Sharma escreveu: >> On Tue, May 04, 2010 at 11:16:38AM +0200, Peter Zijlstra wrote: >> > > In a shared multi-core environment, users want to analyze why their >> > > program was slow. In particular, if the code ran slower only on >> > > certain CPUs due to interference from other programs or kernel >> > > threads, they want to know that. >> > >> > But for that you use perf record -a, right? So you record all cpus >> > allways -- otherwise there is no telling what was happening to make it >> > go slow. >> >> The updated patch records the CPU only in the system_wide mode. > > I think this should be done only if you'll actually need it, as in, > "cpu" is one of the sort keys, but that can be done as a followup patch, > but there is another thing I think you need to change, see below. >
How would you know if the user is going to sort by cpu at "perf record" time?
Thanks for taking care of the second part.
-Arun
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