From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758880Ab0CMMfY (ORCPT ); Sat, 13 Mar 2010 07:35:24 -0500 Received: from www84.your-server.de ([213.133.104.84]:54123 "EHLO www84.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758156Ab0CMMfX (ORCPT ); Sat, 13 Mar 2010 07:35:23 -0500 Subject: Re: [Patch] fix MTD CFI/LPDDR flash driver huge latency bug From: Stefani Seibold To: Jamie Lokier Cc: Andrew Morton , David Woodhouse , "Kreuzer, Michael (NSN - DE/Ulm)" , linux-mtd@lists.infradead.org, linux-kernel In-Reply-To: <20100312233820.GH6491@shareable.org> References: <1267894137.18869.0.camel@wall-e> <20100312142344.174bd46f.akpm@linux-foundation.org> <20100312233820.GH6491@shareable.org> Content-Type: text/plain; charset="ISO-8859-15" Date: Sat, 13 Mar 2010 13:35:44 +0100 Message-ID: <1268483744.6339.25.camel@wall-e> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3.1 Content-Transfer-Encoding: 7bit X-Authenticated-Sender: stefani@seibold.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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.