From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751670AbaEWRkE (ORCPT ); Fri, 23 May 2014 13:40:04 -0400 Received: from mail-qg0-f41.google.com ([209.85.192.41]:50238 "EHLO mail-qg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751387AbaEWRkB (ORCPT ); Fri, 23 May 2014 13:40:01 -0400 Date: Fri, 23 May 2014 13:39:57 -0400 From: Tejun Heo To: Vivek Goyal Cc: Jens Axboe , linux-kernel@vger.kernel.org, Li Zefan , cgroups@vger.kernel.org Subject: Re: [PATCH RFC] blkcg: prepare blkcg knobs for default hierarchy Message-ID: <20140523173957.GA31780@htj.dyndns.org> References: <20140414193214.GC16835@htj.dyndns.org> <20140415135359.GA13033@redhat.com> <20140415140650.GI1863@htj.dyndns.org> <20140415141826.GB17018@redhat.com> <20140423170141.GJ4781@htj.dyndns.org> <20140423171720.GF24651@redhat.com> <20140423185231.GA4163@mtj.dyndns.org> <20140423185835.GD22755@redhat.com> <20140423190043.GB4163@mtj.dyndns.org> <20140423192108.GF22755@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140423192108.GF22755@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Vivek. On Wed, Apr 23, 2014 at 03:21:09PM -0400, Vivek Goyal wrote: > What about sync/async differentiation? Throttling layer seems to flag a request sync > only if bio->bi_rw flag has REQ_SYNC set. While CFQ seems to consider > request sync if bio is either read or bio->bi_rw has REQ_SYNC flag set. Working on this again, AFAICS, both treat REQ_SYNC the same way as far as stats are concerned. If SYNC is set, it's sync; otherwise, it's accounted as async whether read or write. Thanks. -- tejun