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From: Namhyung Kim <namhyung@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>, David Ahern <dsahern@gmail.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Jiri Olsa <jolsa@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Andi Kleen <andi@firstfloor.org>,
	Stephane Eranian <eranian@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>
Subject: Re: [PATCHSET 00/16] perf top: Add multi-thread support (v1)
Date: Tue, 15 Dec 2015 02:11:43 +0900	[thread overview]
Message-ID: <20151214171143.GD23614@danjae.kornet> (raw)
In-Reply-To: <20151214165614.GV6357@twins.programming.kicks-ass.net>

On Mon, Dec 14, 2015 at 05:56:14PM +0100, Peter Zijlstra wrote:
> On Tue, Dec 15, 2015 at 01:38:30AM +0900, Namhyung Kim wrote:
> > It requires many changes, but basically I also like the split-up since
> > it's easier to deal with.  IIRC there was an opinion (Andi?) regarding
> > single-file vs multi-file.  The file access will be better for single
> > file so I changed my earlier implementation to use indexed single data
> > file instead of multiple files.
> 
> The page-cache has a lock per inode, so by having all CPUs populate the
> one file you get contention on that.
> 
> Also, I suppose you'll have to arbitrate ranges in that file for each
> cpu to make it work, that too could get you some contention.
> 
> Having a file per cpu avoids all that.

Right.  Now I recall that it was about *report* (not record) time
accessing single file vs. multi files.

At record time we should use file per cpu.  I combined them into
one with index at post-processing time in my earlier work.

Thanks for clarification!
Namhyung

  reply	other threads:[~2015-12-14 17:12 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-10  7:53 [PATCHSET 00/16] perf top: Add multi-thread support (v1) Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 01/16] perf top: Delete half-processed hist entries when exit Namhyung Kim
2015-12-10  9:55   ` 平松雅巳 / HIRAMATU，MASAMI
2015-12-10 18:57     ` Arnaldo Carvalho de Melo
2015-12-14  8:15   ` [tip:perf/core] " tip-bot for Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 02/16] perf top: Fix and cleanup perf_top__record_precise_ip() Namhyung Kim
2015-12-10 19:04   ` Arnaldo Carvalho de Melo
2015-12-11  2:27     ` Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 03/16] perf top: Factor out warnings about kernel addresses and symbols Namhyung Kim
2015-12-10 19:07   ` Arnaldo Carvalho de Melo
2015-12-14  1:44     ` Namhyung Kim
2015-12-14  2:02       ` Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 04/16] perf top: Factor out warnings in perf_top__record_precise_ip() Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 05/16] perf top: Show warning messages in the display thread Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 06/16] perf top: Get rid of access to hists->lock in perf_top__record_precise_ip() Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 07/16] perf hists: Pass hists struct to hist_entry_iter struct Namhyung Kim
2015-12-13 23:15   ` Jiri Olsa
2015-12-14  1:45     ` Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 08/16] perf tools: Export a couple of hist functions Namhyung Kim
2015-12-13 23:17   ` Jiri Olsa
2015-12-10  7:53 ` [PATCH/RFC 09/16] perf tools: Update hist entry's hists pointer Namhyung Kim
2015-12-13 23:23   ` Jiri Olsa
2015-12-13 23:28     ` Jiri Olsa
2015-12-14  1:51       ` Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 10/16] perf hist: Add events_stats__add() and hists__add_stats() Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 11/16] perf top: Implement basic parallel processing Namhyung Kim
2015-12-14  9:23   ` Jiri Olsa
2015-12-14  9:35     ` Jiri Olsa
2015-12-15  2:08       ` Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 12/16] perf tools: Reduce lock contention when processing events Namhyung Kim
2015-12-14  8:43   ` Jiri Olsa
2015-12-15  2:03     ` Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 13/16] perf top: Protect the seen list using mutex Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 14/16] perf top: Separate struct perf_top_stats Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 15/16] perf top: Add --num-thread option Namhyung Kim
2015-12-10  7:53 ` [PATCH/RFC 16/16] perf tools: Skip dso front cache for multi-threaded lookup Namhyung Kim
2015-12-10  8:01 ` [PATCHSET 00/16] perf top: Add multi-thread support (v1) Ingo Molnar
2015-12-10  8:49   ` Namhyung Kim
2015-12-11  8:11     ` Ingo Molnar
2015-12-11 15:01       ` David Ahern
2015-12-14  1:12         ` Namhyung Kim
2015-12-14  9:26         ` Peter Zijlstra
2015-12-14  9:38           ` Ingo Molnar
2015-12-14 14:55             ` David Ahern
2015-12-14 16:26               ` Arnaldo Carvalho de Melo
2015-12-14 16:41                 ` Peter Zijlstra
2015-12-14 17:52                   ` Arnaldo Carvalho de Melo
2015-12-14 16:38             ` Namhyung Kim
2015-12-14 16:56               ` Peter Zijlstra
2015-12-14 17:11                 ` Namhyung Kim [this message]
2015-12-14 14:46           ` David Ahern
2015-12-14 17:06             ` Namhyung Kim
2015-12-14 17:54               ` Arnaldo Carvalho de Melo
2015-12-14 16:25           ` Namhyung Kim
2015-12-14 16:44             ` Peter Zijlstra

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