From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:55884 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726583AbeKICn3 (ORCPT ); Thu, 8 Nov 2018 21:43:29 -0500 Date: Thu, 8 Nov 2018 12:07:01 -0500 From: Mike Snitzer To: Christoph Hellwig Cc: Mikulas Patocka , "Alasdair G. Kergon" , dm-devel@redhat.com, linux-block@vger.kernel.org, axboe@kernel.dk Subject: Re: [patch 5/5] block: use a driver-specific handler for the "inflight" value Message-ID: <20181108170701.GA29107@redhat.com> References: <20181106213858.391264280@debian-a64.vm> <20181108145240.GA20087@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20181108145240.GA20087@infradead.org> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Thu, Nov 08 2018 at 9:52am -0500, Christoph Hellwig wrote: > On Tue, Nov 06, 2018 at 10:35:03PM +0100, Mikulas Patocka wrote: > > Device mapper was converted to percpu inflight counters. In order to > > display the correct values in the "inflight" sysfs file, we need a custom > > callback that sums the percpu counters. > > The attribute that calls this is per-partition, while your method > is per-queue, so there is some impedence mismatch here. > > Is there any way you could look into just making the generic code > use percpu counters? Discussed doing that with Jens and reported as much here: https://www.redhat.com/archives/dm-devel/2018-November/msg00068.html And Jens gave additional context for why yet another attempt to switch block core's in_flight to percpu counters is doomed (having already been proposed and rejected twice): https://www.redhat.com/archives/dm-devel/2018-November/msg00071.html And yes, definitely should've cc'd linux-block (now added). Mike