linux-kernel - Re: [patch] mm, vmpressure: add high level

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Message-ID: <20131017030512.GA21327@teo>
Date:	Wed, 16 Oct 2013 20:05:12 -0700
From:	Anton Vorontsov <anton@...msg.org>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Hocko <mhocko@...e.cz>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [patch] mm, vmpressure: add high level

Hello David,

On Wed, Oct 16, 2013 at 05:43:55PM -0700, David Rientjes wrote:
> Vmpressure has two important levels: medium and critical.  Medium is 
> defined at 60% and critical is defined at 95%.
> 
> We have a customer who needs a notification at a higher level than medium, 
> which is slight to moderate reclaim activity, and before critical to start 
> throttling incoming requests to save memory and avoid oom.
> 
> This patch adds the missing link: a high level defined at 80%.
> 
> In the future, it would probably be better to allow the user to specify an 
> integer ratio for the notification rather than relying on arbitrarily 
> specified levels.

Does the customer need to differentiate the two levels (medium and high),
or the customer only interested in this (80%) specific level?

In the latter case, instead of adding a new level I would vote for adding
a [sysfs] knob for modifying medium level's threshold.

Thanks,

Anton
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