Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:35034 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726859AbeKSTI4 (ORCPT ); Mon, 19 Nov 2018 14:08:56 -0500 Date: Mon, 19 Nov 2018 16:45:23 +0800 From: Ming Lei To: Omar Sandoval Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Kent Overstreet , Mike Snitzer , dm-devel@redhat.com, Alexander Viro , linux-fsdevel@vger.kernel.org, Shaohua Li , linux-raid@vger.kernel.org, linux-erofs@lists.ozlabs.org, David Sterba , linux-btrfs@vger.kernel.org, "Darrick J . Wong" , linux-xfs@vger.kernel.org, Gao Xiang , Christoph Hellwig , Theodore Ts'o , linux-ext4@vger.kernel.org, Coly Li , linux-bcache@vger.kernel.org, Boaz Harrosh , Bob Peterson , cluster-devel@redhat.com Subject: Re: [PATCH V10 14/19] block: enable multipage bvecs Message-ID: <20181119084522.GK16736@ming.t460p> References: <20181115085306.9910-1-ming.lei@redhat.com> <20181115085306.9910-15-ming.lei@redhat.com> <20181116015627.GI23828@vader> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181116015627.GI23828@vader> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Nov 15, 2018 at 05:56:27PM -0800, Omar Sandoval wrote: > On Thu, Nov 15, 2018 at 04:53:01PM +0800, Ming Lei wrote: > > This patch pulls the trigger for multi-page bvecs. > > > > Now any request queue which supports queue cluster will see multi-page > > bvecs. > > > > Cc: Dave Chinner > > Cc: Kent Overstreet > > Cc: Mike Snitzer > > Cc: dm-devel@redhat.com > > Cc: Alexander Viro > > Cc: linux-fsdevel@vger.kernel.org > > Cc: Shaohua Li > > Cc: linux-raid@vger.kernel.org > > Cc: linux-erofs@lists.ozlabs.org > > Cc: David Sterba > > Cc: linux-btrfs@vger.kernel.org > > Cc: Darrick J. Wong > > Cc: linux-xfs@vger.kernel.org > > Cc: Gao Xiang > > Cc: Christoph Hellwig > > Cc: Theodore Ts'o > > Cc: linux-ext4@vger.kernel.org > > Cc: Coly Li > > Cc: linux-bcache@vger.kernel.org > > Cc: Boaz Harrosh > > Cc: Bob Peterson > > Cc: cluster-devel@redhat.com > > Signed-off-by: Ming Lei > > --- > > block/bio.c | 24 ++++++++++++++++++------ > > 1 file changed, 18 insertions(+), 6 deletions(-) > > > > diff --git a/block/bio.c b/block/bio.c > > index 6486722d4d4b..ed6df6f8e63d 100644 > > --- a/block/bio.c > > +++ b/block/bio.c > > This comment above __bio_try_merge_page() doesn't make sense after this > change: > > This is a > a useful optimisation for file systems with a block size smaller than the > page size. > > Can you please get rid of it in this patch? I understand __bio_try_merge_page() still works for original cases, so looks the optimization for sub-pagesize is still there too, isn't it? > > > @@ -767,12 +767,24 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page, > > > > if (bio->bi_vcnt > 0) { > > struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; > > - > > - if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len) { > > - bv->bv_len += len; > > - bio->bi_iter.bi_size += len; > > - return true; > > - } > > + struct request_queue *q = NULL; > > + > > + if (page == bv->bv_page && off == (bv->bv_offset + bv->bv_len) > > + && (off + len) <= PAGE_SIZE) > > + goto merge; > > The parentheses around (bv->bv_offset + bv->bv_len) and (off + len) are > unnecessary noise. > > What's the point of the new (off + len) <= PAGE_SIZE check? Yeah, I don't know why I did it, :-(, the check is absolutely always true. > > > + > > + if (bio->bi_disk) > > + q = bio->bi_disk->queue; > > + > > + /* disable multi-page bvec too if cluster isn't enabled */ > > + if (!q || !blk_queue_cluster(q) || > > + ((page_to_phys(bv->bv_page) + bv->bv_offset + bv->bv_len) != > > + (page_to_phys(page) + off))) > > More unnecessary parentheses here. OK. Thanks, Ming