Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754039AbbGPPBb (ORCPT ); Thu, 16 Jul 2015 11:01:31 -0400 Received: from mail-ig0-f170.google.com ([209.85.213.170]:36595 "EHLO mail-ig0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751000AbbGPPBa (ORCPT ); Thu, 16 Jul 2015 11:01:30 -0400 MIME-Version: 1.0 In-Reply-To: <55A7C449.4030406@kernel.dk> References: <1437016607-375-1-git-send-email-tom.leiming@gmail.com> <55A7C449.4030406@kernel.dk> Date: Thu, 16 Jul 2015 23:01:29 +0800 Message-ID: Subject: Re: [PATCH 0/4] block: account io: kill atomic operations From: Ming Lei To: Jens Axboe Cc: Linux Kernel Mailing List , Mike Snitzer , Tejun Heo Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1332 Lines: 46 On Thu, Jul 16, 2015 at 10:48 PM, Jens Axboe wrote: > On 07/15/2015 09:16 PM, Ming Lei wrote: >> >> Hi, >> >> This patches kills two kinds of atomic operations in block >> accounting I/O. >> >> The 1st two patches convert atomic refcount of partition >> into percpu refcount. >> >> The 2nd two patches converts partition->in_flight[] into percpu >> variable. >> >> With this change, ~15% throughput improvement can be observed >> when running fio(randread) over null blk in a dual-socket >> environment. > > > I've played with this before, but always ran into the hurdle of making > part_in_flight() too expensive ended up hurting results in the end. Making Yes, it is a bit expensive, but it is only run at most one time per tick for one partition. > the inc/dec parts of accounting percpu is a no-brainer, unfortunately the > summing then becomes pretty expensive. I'll run this through some testing > and see what kind of results I get. The first two patches should be fine, and it still can get ~8% improvement in my test. > > -- > Jens Axboe > -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/