linux-kernel - Re: [Patch] fix MTD CFI/LPDDR flash driver huge latency bug

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Message-ID: <1268483744.6339.25.camel@wall-e>
Date:	Sat, 13 Mar 2010 13:35:44 +0100
From:	Stefani Seibold <stefani@...bold.net>
To:	Jamie Lokier <jamie@...reable.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	David Woodhouse <dwmw2@...radead.org>,
	"Kreuzer, Michael (NSN - DE/Ulm)" <michael.kreuzer@....com>,
	linux-mtd@...ts.infradead.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [Patch] fix MTD CFI/LPDDR flash driver huge latency bug

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@...bold.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.



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