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Date: Tue, 31 Mar 2015 09:27:30 +0900 From: Namhyung Kim <namhyung@...nel.org> To: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com> Cc: Jiri Olsa <jolsa@...hat.com>, David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>, Stephane Eranian <eranian@...gle.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [BUG] segfault in perf-top -- thread refcnt On Mon, Mar 30, 2015 at 12:13:03PM -0300, Arnaldo Carvalho de Melo wrote: > Em Mon, Mar 30, 2015 at 11:58:05AM -0300, Arnaldo Carvalho de Melo escreveu: > > Em Mon, Mar 30, 2015 at 09:48:52PM +0900, Namhyung Kim escreveu: > > > But this makes every sample processing grabs and releases the lock so > > > might cause high overhead. It can be a problem if such processing is > > > done parallelly like my multi-thread work. :-/ > > > > Still untested, using rw lock, next step is auditing the > > machine__findnew_thread users that really should be using > > machine__find_thread, i.e. grabbing just the reader lock, and measuring > > the overhead of using a pthread rw lock instead of pthread_mutex_t as > > Jiri is doing. > > Don't bother trying it, doesn't even compile ;-\ OK. :) But I think rw lock still has not-so-low overhead as it involves atomic operations and cache misses. Thanks, Namhyung -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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