Messages in this thread | | | Date | Thu, 16 Jun 2011 17:18:39 +0200 | From | Frederic Weisbecker <> | Subject | Re: scheduler / perf stat question about CPU-migrations |
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On Thu, Jun 16, 2011 at 04:11:03PM +0100, Pádraig Brady wrote: > On 16/06/11 16:03, Frederic Weisbecker wrote: > > On Thu, Jun 16, 2011 at 10:46:26AM -0400, Theodore Ts'o wrote: > >> Can someone tell me how I'm being confused? > >> > >> I ran the following command as root: > >> > >> perf stat schedtool -a 1 -e e2fsck -ft /dev/funarg/kbuild > > > > A theory is that schedtool does: > > > > if (!fork()) { > > set affinity there > > launch e2fsck > > } > > Well `taskset` and `chrt` from util-linux don't fork at least, > so you could try those instead.
Even if they don't fork and change their own affinity, you'll get migrations that happened since taskset/chrt were launched.
The only solution is too set perf affinity itself:
schedtool -a 1 -e perf stat -- e2fsck -ft /dev/funarg/kbuild
Taskset would work too.
> > I also suggest protecting the command with -- > in case perf is not stopping at the first unrecognized option. > > cheers, > Pádraig. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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