From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH 0/8] sdhci: Move real work out of an atomic context Date: Wed, 21 Jul 2010 14:13:52 -0700 Message-ID: <20100721141352.d7993493.akpm@linux-foundation.org> References: <20100714130728.GA27339@oksana.dev.rtsoft.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:37714 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754932Ab0GUVO5 (ORCPT ); Wed, 21 Jul 2010 17:14:57 -0400 In-Reply-To: <20100714130728.GA27339@oksana.dev.rtsoft.ru> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Anton Vorontsov Cc: Wolfram Sang , Albert Herranz , Matt Fleming , Ben Dooks , Pierre Ossman , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org On Wed, 14 Jul 2010 17:07:28 +0400 Anton Vorontsov wrote: > Hi all, > > Currently the sdhci driver does everything in the atomic context. > And what is worse, PIO transfers are made from the IRQ handler. > > This causes huge latencies (up to 120 ms). On some P2020 SOCs, > DMA and card detection is broken, which means that kernel polls > for the card via PIO transfers every second. Needless to say > that this is quite bad. > > So, this patch set reworks sdhci code to avoid atomic context, > almost completely. We only do two device memory operations > in the atomic context, and all the rest is threaded. > > I noticed no throughput drop neither with PIO transfers nor > with DMA (tested on MPC8569E CPU), while latencies should be > greatly improved. > The patchset looks good to me, but it'd be nice to hear from the other people who work on this code, please?