From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753533AbbJOPVI (ORCPT ); Thu, 15 Oct 2015 11:21:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35616 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751222AbbJOPVH (ORCPT ); Thu, 15 Oct 2015 11:21:07 -0400 From: Jeff Moyer To: Ming Lei Cc: Jens Axboe , linux-kernel@vger.kernel.org, Ming Lin , Kent Overstreet , Christoph Hellwig Subject: Re: [PATCH 3/4] blk-mq: check bio_mergeable() early before merging References: <1444793448-9994-1-git-send-email-ming.lei@canonical.com> <1444793448-9994-4-git-send-email-ming.lei@canonical.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Thu, 15 Oct 2015 11:21:04 -0400 In-Reply-To: <1444793448-9994-4-git-send-email-ming.lei@canonical.com> (Ming Lei's message of "Wed, 14 Oct 2015 11:30:47 +0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ming Lei writes: > It isn't necessary to try to merge the bio which is marked > as NOMERGE. > > Signed-off-by: Ming Lei > --- > block/blk-mq.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 546b3b8..deb5f4c 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -671,6 +671,9 @@ static bool blk_mq_attempt_merge(struct request_queue *q, > struct request *rq; > int checked = 8; > > + if (!bio_mergeable(bio)) > + return false; > + > list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) { > int el_ret; > > @@ -1140,7 +1143,7 @@ static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx, > struct blk_mq_ctx *ctx, > struct request *rq, struct bio *bio) > { > - if (!hctx_allow_merges(hctx)) { > + if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) { > blk_mq_bio_to_request(rq, bio); > spin_lock(&ctx->lock); > insert_rq: blk_mq_attempt_merge is only called from blk_mq_merge_queue_io. So, by adding the conditional in blk_mq_merge_queue_io, you don't need any change in blk_mq_attempt_merge. Also, why haven't you updated the non-multiqueue code paths similarly? Cheers, Jeff