From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935946AbcIPPzf (ORCPT ); Fri, 16 Sep 2016 11:55:35 -0400 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:60292 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932582AbcIPPz1 (ORCPT ); Fri, 16 Sep 2016 11:55:27 -0400 Date: Fri, 16 Sep 2016 16:54:31 +0100 From: One Thousand Gnomes To: Andy Lutomirski Cc: "linux-pm@vger.kernel.org" , "Rafael J. Wysocki" , Keith Busch , Jens Axboe , linux-nvme@lists.infradead.org, "linux-kernel@vger.kernel.org" , J Freyensee , Christoph Hellwig Subject: Re: Should drivers like nvme let userspace control their latency via dev_pm_qos? Message-ID: <20160916165431.1f2e6df5@lxorguk.ukuu.org.uk> In-Reply-To: References: Organization: Intel Corporation X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 16 Sep 2016 08:26:03 -0700 Andy Lutomirski wrote: > I'm adding power management to the nvme driver, and I'm exposing > exactly one knob via sysfs: the maximum permissible latency. This > isn't a power domain issue, and it has no dependencies -- it's > literally just the maximum latency that the driver may impose on I/O > for power saving purposes. Why is this in the driver. Surely the latency is a property of the request queue and the requests being made. Now it may well be that its implement as min(list-of-queues) but a device sysfs node seems a strange place to stick it. Alan