From: "Madhusudhan" <madhu.cr@ti.com>
To: 'Pierre Ossman' <pierre@ossman.eu>
Cc: linux-mmc@vger.kernel.org, linux-omap@vger.kernel.org, hch@lst.de
Subject: RE: mmcqd cpu utilization
Date: Wed, 2 Sep 2009 14:57:27 -0500 [thread overview]
Message-ID: <00ae01ca2c07$98d416f0$544ff780@am.dhcp.ti.com> (raw)
In-Reply-To: <20090902194036.07c1f72c@mjolnir.ossman.eu>
> -----Original Message-----
> From: Pierre Ossman [mailto:pierre@ossman.eu]
> Sent: Wednesday, September 02, 2009 12:41 PM
> To: Madhusudhan
> Cc: linux-mmc@vger.kernel.org; linux-omap@vger.kernel.org; hch@lst.de
> Subject: Re: mmcqd cpu utilization
>
> 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.
>
So your guess hints probably at "wait_for_completion(&complete)".
Am I correct?
Regards,
Madhu
> Anything better than that guess will require some profiling. :)
>
> Rgds
> --
> -- Pierre Ossman
>
> WARNING: This correspondence is being monitored by the
> Swedish government. Make sure your server uses encryption
> for SMTP traffic and consider using PGP for end-to-end
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next prev parent reply other threads:[~2009-09-02 19:57 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
2009-09-02 19:57 ` Madhusudhan [this message]
2009-09-02 20:00 ` Dasgupta, Romit
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