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Date: Mon, 30 Mar 2015 21:46:35 -0300 From: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com> To: Namhyung Kim <namhyung@...nel.org> 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 Em Tue, Mar 31, 2015 at 09:27:30AM +0900, Namhyung Kim escreveu: > 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. But we will have to serialize access to the data structure at some point... - Arnaldo -- 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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