linux-kernel - Re: [PATCH] perf sched map: Add command-name option to filter the output map

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Message-ID: <ZmKtlQdwk5uwha06@chenyu5-mobl2>
Date: Fri, 7 Jun 2024 14:49:57 +0800
From: Chen Yu <yu.c.chen@...el.com>
To: Madadi Vineeth Reddy <vineethr@...ux.ibm.com>
CC: <acme@...nel.org>, <peterz@...radead.org>, <mingo@...hat.com>,
	<namhyung@...nel.org>, <mark.rutland@....com>,
	<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
	<irogers@...gle.com>, <adrian.hunter@...el.com>, <kan.liang@...ux.intel.com>,
	<acme@...hat.com>, <atrajeev@...ux.vnet.ibm.com>, <kjain@...ux.ibm.com>,
	<linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf sched map: Add command-name option to filter the
 output map

On 2024-04-17 at 20:55:21 +0530, Madadi Vineeth Reddy wrote:
> By default, perf sched map prints sched-in events for all the tasks
> which may not be required all the time as it prints lot of symbols
> and rows to the terminal.
> 
> With --command-name option, one could specify the specific command
> for which the map has to be shown. This would help in analyzing the
> CPU usage patterns easier for that specific command. Since multiple
> PID's might have the same command name, using command-name filter
> would be more useful for debugging.
> 
> For other tasks, instead of printing the symbol, ** is printed and
> the same . is used to represent idle. ** is used instead of symbol
> for other tasks because it helps in clear visualization of command
> of interest and secondly the symbol itself doesn't mean anything
> because the sched-in of that symbol will not be printed(first sched-in
> contains pid and the corresponding symbol).
> 
> 6.8.0
> ======
>   *A0                   213864.670142 secs A0 => migration/0:18
>   *.                    213864.670148 secs .  => swapper:0
>    .  *B0               213864.670217 secs B0 => migration/1:21
>    .  *.                213864.670223 secs
>    .   .  *C0           213864.670247 secs C0 => migration/2:26
>    .   .  *.            213864.670252 secs
> 
> 6.8.0 + patch (--command-name = schbench)
> =============
>    **  .   ** *A0       213864.671055 secs A0 => schbench:104834
>   *B0  .   .   A0       213864.671156 secs B0 => schbench:104835
>   *C0  .   .   A0       213864.671187 secs C0 => schbench:104836
>   *D0  .   .   A0       213864.671219 secs D0 => schbench:104837
>   *E0  .   .   A0       213864.671250 secs E0 => schbench:104838
>    E0  .  *D0  A0
> 
> This helps in visualizing how a benchmark like schbench is spread over
> the available cpus while also knowing which cpus are idle(.) and which
> are not(**). This will be more useful as number of CPUs increase.
> 
> Signed-off-by: Madadi Vineeth Reddy <vineethr@...ux.ibm.com>
> ---
>  tools/perf/Documentation/perf-sched.txt |  4 ++++
>  tools/perf/builtin-sched.c              | 17 ++++++++++++++---
>  2 files changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/Documentation/perf-sched.txt b/tools/perf/Documentation/perf-sched.txt
> index 5fbe42bd599b..b04a37560935 100644
> --- a/tools/perf/Documentation/perf-sched.txt
> +++ b/tools/perf/Documentation/perf-sched.txt
> @@ -94,6 +94,10 @@ OPTIONS for 'perf sched map'
>  --color-pids::
>  	Highlight the given pids.
>  
> +--command-name::
> +	Map output only for the given command name.
> +	(** indicates other tasks while . is idle).
> +
>  OPTIONS for 'perf sched timehist'
>  ---------------------------------
>  -k::
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index 0fce7d8986c0..e60836da53e5 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -156,6 +156,7 @@ struct perf_sched_map {
>  	const char		*color_pids_str;
>  	struct perf_cpu_map	*color_cpus;
>  	const char		*color_cpus_str;
> +	const char		*command;
>  	struct perf_cpu_map	*cpus;
>  	const char		*cpus_str;
>  };
> @@ -1594,8 +1595,6 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
>  
>  	sched->curr_thread[this_cpu.cpu] = thread__get(sched_in);
>  
> -	printf("  ");
> -
>  	new_shortname = 0;
>  	if (!tr->shortname[0]) {
>  		if (!strcmp(thread__comm_str(sched_in), "swapper")) {
> @@ -1605,7 +1604,8 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
>  			 */
>  			tr->shortname[0] = '.';
>  			tr->shortname[1] = ' ';
> -		} else {
> +		} else if (!sched->map.command || !strcmp(thread__comm_str(sched_in),
> +								sched->map.command)) {
>

I've tested on my machine and it looks good. One minor question, can we do
fuzzy name matching? Say, there are many tasks 'a-taskname-b',
and we can filter them via
perf sched map --command-name=taskname

thanks,
Chenyu