From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: "Liang, Kan" <kan.liang@intel.com>
Cc: "peterz@infradead.org" <peterz@infradead.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"jolsa@kernel.org" <jolsa@kernel.org>,
"namhyung@kernel.org" <namhyung@kernel.org>,
"Hunter, Adrian" <adrian.hunter@intel.com>,
"Odzioba, Lukasz" <lukasz.odzioba@intel.com>,
"wangnan0@huawei.com" <wangnan0@huawei.com>,
"hekuang@huawei.com" <hekuang@huawei.com>,
"ast@kernel.org" <ast@kernel.org>,
"ak@linux.intel.com" <ak@linux.intel.com>
Subject: Re: [PATCH RFC V4 1/6] perf tools: lock to protect namespaces and comm list
Date: Mon, 2 Oct 2017 16:34:53 -0300 [thread overview]
Message-ID: <20171002193453.GD2869@kernel.org> (raw)
In-Reply-To: <37D7C6CF3E00A74B8858931C1DB2F077537CD725@SHSMSX103.ccr.corp.intel.com>
Em Mon, Oct 02, 2017 at 07:14:10PM +0000, Liang, Kan escreveu:
> > Em Fri, Sep 29, 2017 at 07:47:52AM -0700, kan.liang@intel.com escreveu:
> > > From: Kan Liang <kan.liang@intel.com>
> > >
> > > Add two locks to protect namespaces_list and comm_list.
> > >
> > > The lock is only needed for multithreaded code, so using mutex
> > > wrappers provided by perf tool.
> > >
> > > Not all the comm_list/namespaces_list accessing are protected, e.g.
> > > thread__exec_comm. Because the multithread code for perf top event
> > > synthesizing does not touch them. They don't need a lock.
> >
> > They don't need a lock _now_, ok I think we can proceed that way, this cset
> > should serve as a warning to people working in further multithreading perf.
> >
>
> Do I need to add some comments in the code to give a warning?
Maybe, but then one can use 'git blame' and see the comments on the
patch introducing the locking.
BTW, I'm applied and tested it, pushed to acme/perf/core.
- Arnaldo
next prev parent reply other threads:[~2017-10-02 19:34 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-29 14:47 [PATCH RFC V4 0/6] perf top optimization kan.liang
2017-09-29 14:47 ` [PATCH RFC V4 1/6] perf tools: lock to protect namespaces and comm list kan.liang
2017-10-02 18:05 ` Arnaldo Carvalho de Melo
2017-10-02 19:14 ` Liang, Kan
2017-10-02 19:34 ` Arnaldo Carvalho de Melo [this message]
2017-10-03 16:44 ` [tip:perf/core] perf tools: Lock " tip-bot for Kan Liang
2017-09-29 14:47 ` [PATCH RFC V4 2/6] perf tools: lock to protect comm_str rb tree kan.liang
2017-10-03 16:45 ` [tip:perf/core] perf tools: Lock " tip-bot for Kan Liang
2017-09-29 14:47 ` [PATCH RFC V4 3/6] perf top: implement multithreading for perf_event__synthesize_threads kan.liang
2017-10-03 16:45 ` [tip:perf/core] perf top: Implement " tip-bot for Kan Liang
2017-09-29 14:47 ` [PATCH RFC V4 4/6] perf top: add option to set the number of thread for event synthesize kan.liang
2017-10-03 16:45 ` [tip:perf/core] perf top: Add " tip-bot for Kan Liang
2017-09-29 14:47 ` [PATCH RFC V4 5/6] perf top: switch to backward overwrite mode kan.liang
2017-09-30 19:48 ` Jiri Olsa
2017-10-02 17:19 ` Liang, Kan
2017-10-02 18:03 ` acme
2017-10-03 8:24 ` Jiri Olsa
2017-09-29 14:47 ` [PATCH RFC V4 6/6] perf top: check the cost of perf_top__mmap_read kan.liang
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