linux-kernel - Re: vmstat: make vmstat_updater deferrable again and shut down on idle

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Message-ID: <CAPub148GRFho0oS9Vf0UdX+2Q84+031DE7jKj6Nxc0o0ZqWEmA@mail.gmail.com>
Date:	Wed, 20 Jan 2016 19:22:09 +0530
From:	Shiraz Hashim <shiraz.linux.kernel@...il.com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Michal Hocko <mhocko@...nel.org>, akpm@...ux-foundation.org,
	linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
	hannes@...xchg.org, penguin-kernel@...ove.sakura.ne.jp
Subject: Re: vmstat: make vmstat_updater deferrable again and shut down on idle

Hi Christoph,

On Fri, Dec 11, 2015 at 2:15 AM, Christoph Lameter <cl@...ux.com> wrote:
> Currently the vmstat updater is not deferrable as a result of commit
> ba4877b9ca51f80b5d30f304a46762f0509e1635. This in turn can cause multiple
> interruptions of the applications because the vmstat updater may run at
> different times than tick processing. No good.
>
> Make vmstate_update deferrable again and provide a function that
> folds the differentials when the processor is going to idle mode thus
> addressing the issue of the above commit in a clean way.
>

The patch makes vmstat_shepherd deferable which if is quiesed
would not schedule vmstat update on other cpus. Wouldn't this
aggravate the problem of vmstat for rest cpus not gettng updated.

regards
Shiraz