linux-kernel - Re: [PATCH] vmpressure: implement strict mode

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Message-ID: <20130626093240.2b9c15ac@redhat.com>
Date:	Wed, 26 Jun 2013 09:32:40 -0400
From:	Luiz Capitulino <lcapitulino@...hat.com>
To:	Anton Vorontsov <anton@...msg.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org, mhocko@...e.cz,
	minchan@...nel.org, akpm@...ux-foundation.org
Subject: Re: [PATCH] vmpressure: implement strict mode

On Tue, 25 Jun 2013 21:03:31 -0700
Anton Vorontsov <anton@...msg.org> wrote:

> On Tue, Jun 25, 2013 at 05:51:29PM -0400, Luiz Capitulino wrote:
> > Currently, applications are notified for the level they registered for
> > _plus_ higher levels.
> > 
> > This is a problem if the application wants to implement different
> > actions for different levels. For example, an application might want
> > to release 10% of its cache on level low, 50% on medium and 100% on
> > critical. To do this, the application has to register a different fd
> > for each event. However, fd low is always going to be notified and
> > and all fds are going to be notified on level critical.
> > 
> > Strict mode solves this problem by strictly notifiying the event
> > an fd has registered for. It's optional. By default we still notify
> > on higher levels.
> > 
> > Signed-off-by: Luiz Capitulino <lcapitulino@...hat.com>
> 
> In the documentation I would add more information about why exactly the
> strict mode makes sense.
> 
> For example, the non-strict fd listener hooked onto the low level makes
> sense for apps that just monitor reclaiming activity (like current Android
> Activity Manager), hooking onto 'medium' non-strict mode makes sense for
> simple load-balancing logic, and the new strict mode is for the cases when
> an application wants to implement some fancy logic as it makes a decision
> based on a concrete level.

OK, I'll respin. But you said it all already, so I'll base my text on
on what you wrote.

> Otherwise, it looks good.
> 
> Acked-by: Anton Vorontsov <anton@...msg.org>

Thanks.
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