From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754213AbbJSP16 (ORCPT ); Mon, 19 Oct 2015 11:27:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54995 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754137AbbJSP1o (ORCPT ); Mon, 19 Oct 2015 11:27:44 -0400 From: Jeff Moyer To: Ming Lei Cc: Jens Axboe , linux-kernel@vger.kernel.org, Ming Lin , Kent Overstreet , Christoph Hellwig Subject: Re: [PATCH v1 4/6] block: check bio_mergeable() early before merging References: <1445097154-18229-1-git-send-email-ming.lei@canonical.com> <1445097154-18229-5-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: Mon, 19 Oct 2015 11:27:41 -0400 In-Reply-To: <1445097154-18229-5-git-send-email-ming.lei@canonical.com> (Ming Lei's message of "Sat, 17 Oct 2015 23:52:32 +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: > After bio splitting is introduced, one bio can be splitted > and it is marked as NOMERGE because it is too fat to be merged, > so check bio_mergeable() earlier to avoid to try to merge it > unnecessarily. > > Signed-off-by: Ming Lei Reviewed-by: Jeff Moyer Ming, do you think we should also add a check in blk_attempt_plug_merge? -Jeff > --- > block/elevator.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/block/elevator.c b/block/elevator.c > index 84d6394..c3555c9 100644 > --- a/block/elevator.c > +++ b/block/elevator.c > @@ -420,7 +420,7 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) > * noxmerges: Only simple one-hit cache try > * merges: All merge tries attempted > */ > - if (blk_queue_nomerges(q)) > + if (blk_queue_nomerges(q) || !bio_mergeable(bio)) > return ELEVATOR_NO_MERGE; > > /*