From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH] block: allow us to change max_segments on the fly To: Josef Bacik , kernel-team@fb.com, linux-block@vger.kernel.org References: <1491246798-1774-1-git-send-email-jbacik@fb.com> From: Jens Axboe Message-ID: <9a782a78-7842-db93-2065-22081d16ab1d@kernel.dk> Date: Mon, 3 Apr 2017 13:15:36 -0600 MIME-Version: 1.0 In-Reply-To: <1491246798-1774-1-git-send-email-jbacik@fb.com> Content-Type: text/plain; charset=windows-1252 List-ID: On 04/03/2017 01:13 PM, Josef Bacik wrote: > For things like NBD we want to be able to experiment with different > sized requests going over the wire. Half of our limit is controled by > max_sectors_kb, but the other half is how many bvec's we can cram into a > request, which is controlled by max_segments. Changing this sysfs knob > to be writeable allows us to be able to control our io limits more > precisely. This is a hw setting for most drivers, we can't make it user settable. If you want it user settable, you'd have to split it in a hw and user setting. -- Jens Axboe