Date: Fri, 16 Nov 2018 14:59:22 +0100
From: Christoph Hellwig <hch@lst.de>
To: Omar Sandoval <osandov@osandov.com>
Cc: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Dave Chinner <dchinner@redhat.com>,
        Kent Overstreet <kent.overstreet@gmail.com>,
        Mike Snitzer <snitzer@redhat.com>, dm-devel@redhat.com,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, Shaohua Li <shli@kernel.org>,
        linux-raid@vger.kernel.org, linux-erofs@lists.ozlabs.org,
        David Sterba <dsterba@suse.com>, linux-btrfs@vger.kernel.org,
        "Darrick J . Wong" <darrick.wong@oracle.com>,
        linux-xfs@vger.kernel.org, Gao Xiang <gaoxiang25@huawei.com>,
        Christoph Hellwig <hch@lst.de>, Theodore Ts'o <tytso@mit.edu>,
        linux-ext4@vger.kernel.org, Coly Li <colyli@suse.de>,
        linux-bcache@vger.kernel.org, Boaz Harrosh <ooo@electrozaur.com>,
        Bob Peterson <rpeterso@redhat.com>, cluster-devel@redhat.com
Subject: Re: [PATCH V10 18/19] block: kill QUEUE_FLAG_NO_SG_MERGE
Message-ID: <20181116135922.GO3165@lst.de>
References: <20181115085306.9910-1-ming.lei@redhat.com> <20181115085306.9910-19-ming.lei@redhat.com> <20181116021811.GM23828@vader>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20181116021811.GM23828@vader>
Sender: linux-ext4-owner@vger.kernel.org

On Thu, Nov 15, 2018 at 06:18:11PM -0800, Omar Sandoval wrote:
> This commit message wasn't very clear. Is it the case that
> QUEUE_FLAG_NO_SG_MERGE is no longer set by any drivers?

I think he wants to say that not doing S/G merging is rather pointless
with the current setup of the I/O path, as it isn't going to save
you a significant amount of cycles.