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Message-ID: <CO6PR11MB563537F134026F22B5610DADEEEE2@CO6PR11MB5635.namprd11.prod.outlook.com>
Date: Fri, 17 May 2024 21:57:52 +0000
From: "Wang, Weilin" <weilin.wang@...el.com>
To: Namhyung Kim <namhyung@...nel.org>
CC: Ian Rogers <irogers@...gle.com>, Arnaldo Carvalho de Melo
<acme@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar
<mingo@...hat.com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, "Hunter, Adrian" <adrian.hunter@...el.com>, Kan
Liang <kan.liang@...ux.intel.com>, "linux-perf-users@...r.kernel.org"
<linux-perf-users@...r.kernel.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "Taylor, Perry" <perry.taylor@...el.com>,
"Alt, Samantha" <samantha.alt@...el.com>, "Biggers, Caleb"
<caleb.biggers@...el.com>
Subject: RE: [RFC PATCH v8 3/7] perf stat: Fork and launch perf record when
perf stat needs to get retire latency value for a metric.
> -----Original Message-----
> From: Namhyung Kim <namhyung@...nel.org>
> Sent: Friday, May 17, 2024 2:43 PM
> To: Wang, Weilin <weilin.wang@...el.com>
> Cc: Ian Rogers <irogers@...gle.com>; Arnaldo Carvalho de Melo
> <acme@...nel.org>; Peter Zijlstra <peterz@...radead.org>; Ingo Molnar
> <mingo@...hat.com>; Alexander Shishkin
> <alexander.shishkin@...ux.intel.com>; Jiri Olsa <jolsa@...nel.org>; Hunter,
> Adrian <adrian.hunter@...el.com>; Kan Liang <kan.liang@...ux.intel.com>;
> linux-perf-users@...r.kernel.org; linux-kernel@...r.kernel.org; Taylor, Perry
> <perry.taylor@...el.com>; Alt, Samantha <samantha.alt@...el.com>; Biggers,
> Caleb <caleb.biggers@...el.com>
> Subject: Re: [RFC PATCH v8 3/7] perf stat: Fork and launch perf record when
> perf stat needs to get retire latency value for a metric.
>
> On Tue, May 14, 2024 at 10:44 PM <weilin.wang@...el.com> wrote:
> >
> > From: Weilin Wang <weilin.wang@...el.com>
> >
> > When retire_latency value is used in a metric formula, perf stat would fork a
> > perf record process with "-e" and "-W" options. Perf record will collect
> > required retire_latency values in parallel while perf stat is collecting
> > counting values.
> >
> > At the point of time that perf stat stops counting, it would send sigterm
> signal
> > to perf record process and receiving sampling data back from perf record
> from a
> > pipe. Perf stat will then process the received data to get retire latency data
> > and calculate metric result.
> >
> > Another thread is required to synchronize between perf stat and perf record
> > when we pass data through pipe.
> >
> > Signed-off-by: Weilin Wang <weilin.wang@...el.com>
> > Reviewed-by: Ian Rogers <irogers@...gle.com>
> > ---
> [SNIP]
> > diff --git a/tools/perf/util/intel-tpebs.c b/tools/perf/util/intel-tpebs.c
> > new file mode 100644
> > index 000000000000..4b7a98794fae
> > --- /dev/null
> > +++ b/tools/perf/util/intel-tpebs.c
> > @@ -0,0 +1,285 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * intel_pt.c: Intel Processor Trace support
> > + * Copyright (c) 2013-2015, Intel Corporation.
>
> This needs some updates. :)
>
>
> > + */
> > +
> > +
> > +#include <sys/param.h>
> > +#include <subcmd/run-command.h>
> > +#include <thread.h>
> > +#include "intel-tpebs.h"
> > +#include <linux/list.h>
> > +#include <linux/zalloc.h>
> > +#include <linux/err.h>
> > +#include "sample.h"
> > +#include "debug.h"
> > +#include "evlist.h"
> > +#include "evsel.h"
> > +#include "session.h"
> > +#include "tool.h"
> > +#include "metricgroup.h"
> > +#include <sys/stat.h>
> > +#include <sys/file.h>
> > +
> > +
> > +
> > +#define PERF_DATA "-"
> > +#define CONTROL "/tmp/control"
> > +#define ACK "/tmp/ack"
> > +pthread_t reader_thread;
> > +struct child_process *cmd;
> > +struct perf_stat_config *stat_config;
>
> static ?
>
> > +
> > +static int get_perf_record_args(const char **record_argv)
> > +{
> > + int i = 0;
> > + struct tpebs_retire_lat *e;
> > +
> > + pr_debug("Prepare perf record for retire_latency\n");
> > +
> > + record_argv[i++] = "perf";
> > + record_argv[i++] = "record";
> > + record_argv[i++] = "-W";
> > + record_argv[i++] = "--synth=no";
>
> Unfortunately this still synthesizes MMAP records for the kernel
> and modules. As we don't care about them and just want to
> minimize the overhead at the beginning, we can add
> "--tail-synthesize" too.
>
>
> > + record_argv[i++] = "--control=fifo:/tmp/control,/tmp/ack";
>
> This hard-coded path won't work well when more than one users
> want to run the perf command at the same time.
>
Hi Namhyung,
Yes, this is not a good implementation. I'm going to update this named
pipe and all the related code.
Thanks,
Weilin
> Thanks,
> Namhyung
>
> > +
> > + if (stat_config->user_requested_cpu_list) {
> > + record_argv[i++] = "-C";
> > + record_argv[i++] = stat_config->user_requested_cpu_list;
> > + }
> > +
> > + if (stat_config->system_wide)
> > + record_argv[i++] = "-a";
> > +
> > + if (!stat_config->system_wide && !stat_config-
> >user_requested_cpu_list) {
> > + pr_err("Require -a or -C option to run sampling.\n");
> > + return -ECANCELED;
> > + }
> > +
> > + list_for_each_entry(e, &stat_config->tpebs_results, nd) {
> > + record_argv[i++] = "-e";
> > + record_argv[i++] = e->name;
> > + }
> > +
> > + record_argv[i++] = "-o";
> > + record_argv[i++] = PERF_DATA;
> > +
> > + return 0;
> > +}
> > +
> >
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