From: Jiri Olsa <jolsa@redhat.com>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
Petr Mladek <pmladek@suse.com>,
Andrey Zhizhikin <andrey.z@gmail.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Thomas Gleixner <tglx@linutronix.de>,
Kan Liang <kan.liang@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH 5/5] perf synthetic events: Remove use of sscanf from /proc reading
Date: Thu, 2 Apr 2020 15:40:52 +0200 [thread overview]
Message-ID: <20200402134052.GI2518490@krava> (raw)
In-Reply-To: <20200401233945.133550-6-irogers@google.com>
On Wed, Apr 01, 2020 at 04:39:45PM -0700, Ian Rogers wrote:
> The synthesize benchmark, run on a single process and thread, shows
> perf_event__synthesize_mmap_events as the hottest function with fgets
> and sscanf taking the majority of execution time. fscanf performs
> similarly well. Replace the scanf call with manual reading of each field
> of the /proc/pid/maps line, and remove some unnecessary buffering.
> This change also addresses potential, but unlikely, buffer overruns for
> the string values read by scanf.
>
> Performance before is:
> Average synthesis took: 120.195100 usec
> Average data synthesis took: 156.582300 usec
>
> And after is:
> Average synthesis took: 67.189100 usec
> Average data synthesis took: 102.451600 usec
>
> On a Intel Xeon 6154 compiling with Debian gcc 9.2.1.
I can see the speedup as well, thanks!
jirka
next prev parent reply other threads:[~2020-04-02 13:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-01 23:39 [PATCH 0/5] Benchmark and improve event synthesis performance Ian Rogers
2020-04-01 23:39 ` [PATCH 1/5] perf bench: add event synthesis benchmark Ian Rogers
2020-04-02 13:41 ` Jiri Olsa
2020-04-01 23:39 ` [PATCH 2/5] tools api fs: make xxx__mountpoint() more scalable Ian Rogers
2020-04-01 23:39 ` [PATCH 3/5] perf synthetic-events: save 4kb from 2 stack frames Ian Rogers
2020-04-01 23:39 ` [PATCH 4/5] tools api: add a lightweight buffered reading api Ian Rogers
2020-04-02 13:41 ` Jiri Olsa
2020-04-01 23:39 ` [PATCH 5/5] perf synthetic events: Remove use of sscanf from /proc reading Ian Rogers
2020-04-02 13:40 ` Jiri Olsa [this message]
2020-04-02 13:41 ` Jiri Olsa
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