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Date: Thu, 25 Jun 2015 11:00:35 -0700
Message-ID: <CAM_iQpW8+pHOhdnZS7iwE987Qc1AqX0qCRYPvEZx5Xc8Ep+92w@mail.gmail.com>
Subject: Re: [PATCH] proc/schedstat: Expose /proc/<pid>/schedstat if delay
 accounting is enabled
From: Cong Wang <xiyou.wangcong@gmail.com>
To: Balbir Singh <bsingharora@gmail.com>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
        Ingo Molnar <mingo@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Thu, May 28, 2015 at 2:11 AM, Balbir Singh <bsingharora@gmail.com> wrote:
> 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.
>>

[...]

> 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.
>

Why?

If you need the procfs interface, just enable CONFIG_SCHEDSTATS.
If you need the netlink interface, enable CONFIG_TASK_DELAY_ACCT.
They are just two different interfaces for getting the same sched
information, so why make this change?

There must be some reason you don't want to enable
CONFIG_SCHEDSTATS? If so, please add it in the changelog.

My guess is it depends on DEBUG_KERNEL which is not what you
want? But I see no reason it should have that dependency, it just
exposes some stats, looks like can be just removed (and moved out
of Kconfig,debug of course).