Re: [PATCH] proc/schedstat: Expose /proc/<pid>/schedstat if delay accounting is enabled

From: Balbir Singh <bsingharora@gmail.com>
To: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: mingo@kernel.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] proc/schedstat: Expose /proc/<pid>/schedstat if delay accounting is enabled
Date: Thu, 28 May 2015 14:41:10 +0530	[thread overview]
Message-ID: <CAKTCnzm5A6n=jvskHqUmpdq7yynzKqwuVFJL-ia=3PmgDeBV-w@mail.gmail.com> (raw)
In-Reply-To: <1432537954-26665-1-git-send-email-naveen.n.rao@linux.vnet.ibm.com>

On Mon, May 25, 2015 at 12:42 PM, Naveen N. Rao
<naveen.n.rao@linux.vnet.ibm.com> wrote:
> /proc/<pid>/schedstat is currently only available if CONFIG_SCHEDSTATS is
> enabled. But, all the fields that this exposes are available and valid
> if CONFIG_TASK_DELAY_ACCT is enabled as well.
>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> ---
>  fs/proc/base.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 093ca14..3ece303 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -304,14 +304,17 @@ static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
>  }
>  #endif
>
> -#ifdef CONFIG_SCHEDSTATS
> +#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
>  /*
>   * Provides /proc/PID/schedstat
>   */
>  static int proc_pid_schedstat(struct seq_file *m, struct pid_namespace *ns,
>                               struct pid *pid, struct task_struct *task)
>  {
> -       seq_printf(m, "%llu %llu %lu\n",
> +       if (unlikely(!sched_info_on()))
> +               seq_printf(m, "0 0 0\n");
> +       else
> +               seq_printf(m, "%llu %llu %lu\n",
>                    (unsigned long long)task->se.sum_exec_runtime,
>                    (unsigned long long)task->sched_info.run_delay,
>                    task->sched_info.pcount);
> @@ -2600,7 +2603,7 @@ static const struct pid_entry tgid_base_stuff[] = {
>  #ifdef CONFIG_STACKTRACE
>         ONE("stack",      S_IRUSR, proc_pid_stack),
>  #endif
> -#ifdef CONFIG_SCHEDSTATS
> +#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
>         ONE("schedstat",  S_IRUGO, proc_pid_schedstat),
>  #endif
>  #ifdef CONFIG_LATENCYTOP
> @@ -2948,7 +2951,7 @@ static const struct pid_entry tid_base_stuff[] = {
>  #ifdef CONFIG_STACKTRACE
>         ONE("stack",      S_IRUSR, proc_pid_stack),
>  #endif
> -#ifdef CONFIG_SCHEDSTATS
> +#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
>         ONE("schedstat", S_IRUGO, proc_pid_schedstat),
>  #endif
>  #ifdef CONFIG_LATENCYTOP
> --

The change looks reasonable, from what I can understand you want these
changes so that you can use /proc/<pid>/schedstat instead of the
netlink interface when CONFIG_TASK_DELAY_ACCT is enabled.

Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>