From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752669AbaFECJn (ORCPT ); Wed, 4 Jun 2014 22:09:43 -0400 Received: from mail-ie0-f182.google.com ([209.85.223.182]:64958 "EHLO mail-ie0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751591AbaFECJm (ORCPT ); Wed, 4 Jun 2014 22:09:42 -0400 Date: Thu, 5 Jun 2014 10:09:34 +0800 From: Shaohua Li To: Jens Axboe Cc: Matias =?iso-8859-1?Q?Bj=F8rling?= , "Sam Bradshaw (sbradshaw)" , LKML Subject: Re: [PATCH] block: per-cpu counters for in-flight IO accounting Message-ID: <20140605020934.GB13953@kernel.org> References: <1399627061-5960-1-git-send-email-m@bjorling.me> <1399627061-5960-2-git-send-email-m@bjorling.me> <536CE25C.5040107@kernel.dk> <536D0537.7010905@kernel.dk> <20140530121119.GA1637@kernel.org> <53888C80.2020206@kernel.dk> <20140604103901.GA14383@kernel.org> <538F7CCE.3050508@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <538F7CCE.3050508@kernel.dk> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 04, 2014 at 02:08:46PM -0600, Jens Axboe wrote: > On 06/04/2014 05:29 AM, Matias Bjørling wrote: > > It's in > > > > blk_io_account_start > > part_round_stats > > part_round_state_single > > part_in_flight > > > > I like the granularity idea. > > And similarly from blk_io_account_done() - which makes it even worse, > since it at both ends of the IO chain. But part_round_state_single is supposed to only call part_in_flight every jiffery. Maybe we need something below: 1. set part->stamp immediately 2. fixed granularity Untested though. diff --git a/block/blk-core.c b/block/blk-core.c index 40d6548..5f0acaa 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1270,17 +1270,19 @@ static void part_round_stats_single(int cpu, struct hd_struct *part, unsigned long now) { int inflight; + unsigned long old_stamp; - if (now == part->stamp) + if (time_before(now, part->stamp + msecs_to_jiffies(10))) return; + old_stamp = part->stamp; + part->stamp = now; inflight = part_in_flight(part); if (inflight) { __part_stat_add(cpu, part, time_in_queue, - inflight * (now - part->stamp)); - __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); + inflight * (now - old_stamp)); + __part_stat_add(cpu, part, io_ticks, (now - old_stamp)); } - part->stamp = now; } /**