linux-kernel - Re: [PATCH 4/4] input: evdev: only wake poll on EV

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Message-ID: <20110325074920.GF2590@core.coreip.homeip.net>
Date:	Fri, 25 Mar 2011 00:49:20 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Jeff Brown <jeffbrown@...roid.com>
Cc:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] input: evdev: only wake poll on EV_SYN

On Tue, Mar 22, 2011 at 06:04:04PM -0700, Jeff Brown wrote:
> On SMP systems, it is possible for an evdev client blocked on poll()
> to wake up and read events from the evdev ring buffer at the same
> rate as they are enqueued.  This can result in high CPU usage,
> particularly for MT devices, because the client ends up reading
> events one at a time instead of reading complete packets.  This patch
> ensures that the client only wakes from poll() when a complete packet
> is ready to be read.

Doesn't this only help with very first packet after a pause in event
stream?

-- 
Dmitry
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