From: Pierre Ossman <pierre@ossman.eu>
To: Madhusudhan <madhu.cr@ti.com>
Cc: linux-mmc@vger.kernel.org, linux-omap@vger.kernel.org, hch@lst.de
Subject: Re: mmcqd cpu utilization
Date: Wed, 2 Sep 2009 19:40:36 +0200 [thread overview]
Message-ID: <20090902194036.07c1f72c@mjolnir.ossman.eu> (raw)
In-Reply-To: <007301ca2bf2$2888e2a0$544ff780@am.dhcp.ti.com>
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On Wed, 2 Sep 2009 12:23:59 -0500
"Madhusudhan" <madhu.cr@ti.com> wrote:
> Hi,
>
> Has anyone monitored the cpu utilization percentage when a MMC/SD card is in
> use? I have noticed that mmc_queue_thread "mmcqd" consumes a lot of cpu
> cycles in a periodic fashion. What I mean here is that I see spikes of high
> cpu utilization due to mmcqd. There will a cp or similar which will be
> already consuming cpu to transfer data to the MMC/SD device. Further mmcqd
> increases that load randomly to a high number.
>
> Has anyone seen similar behavior? Any thoughts?
>
My guess would be that the omap driver doesn't (cannot?) use the
hardware to wait for busy to end, so the system must poll.
Anything better than that guess will require some profiling. :)
Rgds
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next prev parent reply other threads:[~2009-09-02 17:40 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-02 17:23 mmcqd cpu utilization Madhusudhan
2009-09-02 17:40 ` Pierre Ossman [this message]
2009-09-02 19:57 ` Madhusudhan
2009-09-02 20:00 ` Dasgupta, Romit
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