Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754261AbZGBAvS (ORCPT ); Wed, 1 Jul 2009 20:51:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752428AbZGBAvI (ORCPT ); Wed, 1 Jul 2009 20:51:08 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:51339 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751565AbZGBAvH (ORCPT ); Wed, 1 Jul 2009 20:51:07 -0400 Message-ID: <4A4C042F.7080403@cn.fujitsu.com> Date: Thu, 02 Jul 2009 08:49:51 +0800 From: Shan Wei User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Jens Axboe CC: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Jeff Moyer Subject: Re: [PATCH 2/2] cfq-iosched: get rid of the need for __GFP_FAIL in cfq_find_alloc_queue() References: <1246007120-24034-1-git-send-email-jens.axboe@oracle.com> <1246007120-24034-3-git-send-email-jens.axboe@oracle.com> <4A4B2C3D.7090800@cn.fujitsu.com> <20090701093235.GX23611@kernel.dk> In-Reply-To: <20090701093235.GX23611@kernel.dk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1377 Lines: 39 Jens Axboe said: > On Wed, Jul 01 2009, Shan Wei wrote: >> Jens Axboe said: >>> Setup an emergency fallback cfqq that we allocate at IO scheduler init >>> time. If the slab allocation fails in cfq_find_alloc_queue(), we'll just >>> punt IO to that cfqq instead. This ensures that cfq_find_alloc_queue() >>> never fails without having to ensure free memory. >>> >>> Signed-off-by: Jens Axboe >>> --- >>> >>> @@ -1740,11 +1745,8 @@ cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc, >>> cfqq = *async_cfqq; >>> } >>> >>> - if (!cfqq) { >>> + if (!cfqq) >>> cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); >>> - if (!cfqq) >>> - return NULL; >>> - } >> I jsut reviewed the code and found that the check of cfqq is also redundant >> after doing cfq_get_queue() in cfq_set_request. >> >> The patch is based on Linus's main tree. > > It's not redundant in Linus' tree, cfq_get_queue() can return NULL for > != __GFP_WAIT. > Yes. So, the patch is only for "for-linus" branch of your tree, not for Linus's tree. I noticed the patch is in your tree now, thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/