From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751643AbcIBHdy (ORCPT ); Fri, 2 Sep 2016 03:33:54 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:8168 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750979AbcIBHdx (ORCPT ); Fri, 2 Sep 2016 03:33:53 -0400 Subject: Re: [PATCH] f2fs: merge WRITE bio into previous WRITE_SYNC To: Jaegeuk Kim , , , References: <20160827005358.91477-1-jaegeuk@kernel.org> From: Chao Yu Message-ID: <10d2270d-6226-a269-c8a4-75bedfd0364c@huawei.com> Date: Fri, 2 Sep 2016 15:33:33 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.0 MIME-Version: 1.0 In-Reply-To: <20160827005358.91477-1-jaegeuk@kernel.org> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020201.57C92B52.01EC,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 293bf25c824992e11f7cf1a9958426f5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jaegeuk, On 2016/8/27 8:53, Jaegeuk Kim wrote: > This can avoid bio splits due to different op_flags. I thought about this, but I think this is not a good idea to increase merging ratio of pages in bio. It breaks the rule of SYNC/ASYNC IO defined by system which indicate degree of IO emergency, finally, some/more non-emergent IO will treated as emergent one by IO scheduler, it will interrupt SYNC IOs in block layer, more seriously, it may make real SYNC IO starvation. Thanks, > > Signed-off-by: Jaegeuk Kim > --- > fs/f2fs/data.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > index 7c8e219..c7c2022 100644 > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -267,6 +267,11 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *fio) > > down_write(&io->io_rwsem); > > + /* WRITE can be merged into previous WRITE_SYNC */ > + if (io->bio && io->last_block_in_bio == fio->new_blkaddr - 1 && > + io->fio.op == fio->op && io->fio.op_flags == WRITE_SYNC) > + fio->op_flags = WRITE_SYNC; > + > if (io->bio && (io->last_block_in_bio != fio->new_blkaddr - 1 || > (io->fio.op != fio->op || io->fio.op_flags != fio->op_flags))) > __submit_merged_bio(io); >