From: <leonid.moiseichuk@nokia.com>
To: <anton.vorontsov@linaro.org>
CC: <kosaki.motohiro@gmail.com>, <penberg@kernel.org>,
        <b.zolnierkie@samsung.com>, <john.stultz@linaro.org>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <linaro-kernel@lists.linaro.org>, <patches@linaro.org>,
        <kernel-team@android.com>
Subject: RE: [PATCH 2/5] vmevent: Convert from deferred timer to deferred
 work
Thread-Topic: [PATCH 2/5] vmevent: Convert from deferred timer to deferred
 work
Thread-Index: AQHNP/HM8KMmZkc4xkKq2ZDXaeCP2Zbvq0sAgAA7gACAACLOoP//7gqAgAAk2GA=
Date: Fri, 8 Jun 2012 08:16:04 +0000
Message-ID: <84FF21A720B0874AA94B46D76DB98269045F7A24@008-AM1MPN1-004.mgdnok.nokia.com>
References: <20120601122118.GA6128@lizard>
 <1338553446-22292-2-git-send-email-anton.vorontsov@linaro.org>
 <4FD170AA.10705@gmail.com> <20120608065828.GA1515@lizard>
 <84FF21A720B0874AA94B46D76DB98269045F7890@008-AM1MPN1-004.mgdnok.nokia.com>
 <20120608075844.GA6362@lizard>
In-Reply-To: <20120608075844.GA6362@lizard>
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> -----Original Message-----
> From: ext Anton Vorontsov [mailto:anton.vorontsov@linaro.org]
> Sent: 08 June, 2012 10:59
... 
> a) Two more context swtiches;
> b) Serialization/deserialization of /proc/vmstat.
> 
> > It also will cause page trashing because user-space code could be pushed
> out from cache if VM decide.
> 
> This can solved by moving a "watcher" to a separate (daemon) process, and
> mlocking it. We do this in ulmkd.

Right. It but it has drawbacks as well e.g. ensure that daemon scheduled properly and propagate reaction decision outside ulmkd.
Also I understand your statement about "watcher" as probably you use one timer for daemon. 
Btw, in my variant (memnotify.c) I used only one timer, it is enough.
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