From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751774AbdJCJVr (ORCPT <rfc822;w@1wt.eu>);
        Tue, 3 Oct 2017 05:21:47 -0400
Received: from bombadil.infradead.org ([65.50.211.133]:58476 "EHLO
        bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751710AbdJCJVp (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 3 Oct 2017 05:21:45 -0400
Date: Tue, 3 Oct 2017 02:21:43 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@fb.com>, linux-block@vger.kernel.org,
        Christoph Hellwig <hch@infradead.org>,
        Mike Snitzer <snitzer@redhat.com>, dm-devel@redhat.com,
        Bart Van Assche <bart.vanassche@sandisk.com>,
        Laurence Oberman <loberman@redhat.com>,
        Paolo Valente <paolo.valente@linaro.org>,
        Oleksandr Natalenko <oleksandr@natalenko.name>,
        Tom Nguyen <tom81094@gmail.com>, linux-kernel@vger.kernel.org,
        Omar Sandoval <osandov@fb.com>
Subject: Re: [PATCH V5 8/8] blk-mq: improve bio merge from blk-mq sw queue
Message-ID: <20171003092143.GF2771@infradead.org>
References: <20170930112655.31451-1-ming.lei@redhat.com>
 <20170930112655.31451-9-ming.lei@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20170930112655.31451-9-ming.lei@redhat.com>
User-Agent: Mutt/1.8.3 (2017-05-23)
X-SRS-Rewrite: SMTP reverse-path rewritten from <hch@infradead.org> by bombadil.infradead.org. See http://www.infradead.org/rpr.html
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

This looks generally good to me, but I really worry about the impact
on very high iops devices.  Did you try this e.g. for random reads
from unallocated blocks on an enterprise NVMe SSD?