linux-kernel - Re: [PATCH 12/12] perf report: Add --task option to display monitored tasks

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Date:   Tue, 9 Jan 2018 10:56:07 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        kernel-team@....com
Subject: Re: [PATCH 12/12] perf report: Add --task option to display
 monitored tasks

Hi Jiri,

On Sun, Jan 07, 2018 at 05:03:56PM +0100, Jiri Olsa wrote:
> Adding --task option to display monitored tasks stored
> in perf.data. Displaying pid/tid/ppid plus the command
> string aligned to distinguish parent and child tasks.
> 
>   $ perf record -a
>   ...
>   $ perf report --task
>   #     pid     tid    ppid  comm
>           0       0      -1 |swapper
>           2       2       0 | kthreadd
>       14080   14080       2 |  kworker/u17:1
>           4       4       2 |  kworker/0:0H
>           6       6       2 |  mm_percpu_wq
>   ...
>           1       1       0 | systemd
>       23242   23242       1 |  firefox
>       23242   23298   23242 |   Cache2 I/O
>       23242   23304   23242 |   GMPThread
>   ...
>        1195    1195       1 |  login
>        1611    1611    1195 |   bash
>        1639    1639    1611 |    startx
>        1663    1663    1639 |     xinit
>        1673    1673    1663 |      xmonad-x86_64-l
>       23939   23939    1673 |       xterm
>       23941   23941   23939 |        bash
>       23963   23963   23941 |         mutt
>       24954   24954   23963 |          offlineimap

Nice! :)


> 
> Link: http://lkml.kernel.org/n/tip-ehvadnmg8b3kdhvgsbuesbr7@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/perf/Documentation/perf-report.txt |   4 +
>  tools/perf/builtin-report.c              | 136 ++++++++++++++++++++++++++++++-
>  2 files changed, 138 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
> index b0d70bf4ddfe..dcf0d154918f 100644
> --- a/tools/perf/Documentation/perf-report.txt
> +++ b/tools/perf/Documentation/perf-report.txt
> @@ -441,6 +441,10 @@ include::itrace.txt[]
>  	Display overall events statistics without any further processing.
>  	(like the one at the end of the perf report -D command)
>  
> +--task::
> +	Display monitored tasks stored in perf data. Displaying pid/tid/ppid
> +	plus the command string aligned to distinguish parent and child tasks.
> +
>  include::callchain-overhead-calculation.txt[]
>  
>  SEE ALSO
> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> index 11d303494b0c..f2ca2cbe63c1 100644
> --- a/tools/perf/builtin-report.c
> +++ b/tools/perf/builtin-report.c
> @@ -15,6 +15,7 @@
>  #include "util/color.h"
>  #include <linux/list.h>
>  #include <linux/rbtree.h>
> +#include <linux/err.h>
>  #include "util/symbol.h"
>  #include "util/callchain.h"
>  #include "util/values.h"
> @@ -61,6 +62,7 @@ struct report {
>  	bool			inverted_callchain;
>  	bool			mem_mode;
>  	bool			stat_mode;
> +	bool			task_mode;
>  	bool			header;
>  	bool			header_only;
>  	bool			nonany_branch_mode;
> @@ -598,6 +600,124 @@ static int stat_print(struct report *rep)
>  	return 0;
>  }
>  
> +static void task_setup(struct report *rep)
> +{
> +	memset(&rep->tool, 0, sizeof(rep->tool));
> +	rep->tool.comm = perf_event__process_comm;
> +	rep->tool.exit = perf_event__process_exit;
> +	rep->tool.fork = perf_event__process_fork;
> +	rep->tool.no_warn = true;
> +}
> +
> +struct task {
> +	struct thread		*thread;
> +	struct list_head	 list;
> +	struct list_head	 children;
> +};
> +
> +static struct task *task_list(struct task *task, struct machine *machine)
> +{
> +	struct thread *parent_thread, *thread = task->thread;
> +	struct task   *parent_task;
> +
> +	/* Already listed. */
> +	if (!list_empty(&task->list))
> +		return NULL;
> +
> +	/* Last one in the chain. */
> +	if (thread->ppid == -1)
> +		return task;
> +
> +	parent_thread = machine__findnew_thread(machine, -1, thread->ppid);

I think it should be machine__find_thread() since creating a new
thread at this stage would lack thread->priv anyway.

Thanks,
Namhyung


> +	if (!parent_thread)
> +		return ERR_PTR(-ENOMEM);
> +
> +	parent_task = thread__priv(parent_thread);
> +	list_add_tail(&task->list, &parent_task->children);
> +	return task_list(parent_task, machine);
> +}