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Subject: Re: [Patch] fix MTD CFI/LPDDR flash driver huge latency bug
From: Stefani Seibold <stefani@seibold.net>
To: Jamie Lokier <jamie@shareable.org>
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Date: Sat, 13 Mar 2010 13:35:44 +0100
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Cc: linux-mtd@lists.infradead.org, Andrew Morton <akpm@linux-foundation.org>,
	David Woodhouse <dwmw2@infradead.org>, "Kreuzer,
	Michael \(NSN - DE/Ulm\)" <michael.kreuzer@nsn.com>,
	linux-kernel <linux-kernel@vger.kernel.org>
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Am Freitag, den 12.03.2010, 23:38 +0000 schrieb Jamie Lokier:
> Andrew Morton wrote:
> > On Sat, 06 Mar 2010 17:48:57 +0100
> > Stefani Seibold <stefani@seibold.net> wrote:
> > 


> > > The patch change all the use of spin_lock operations for xxxx->mutex
> > > into mutex operations, which is exact what the name says and means.
> 
> It would be even better if it also split the critical sections into
> smaller ones with cond_resched() between, so that non-preemptible
> kernels benefit too.
> 

The problem is the memcpy operation which is very slow. A cond_resched
wouldn't help, since the cpu bus is blocked during the transfer of the
word.