From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755168AbcGFPGe (ORCPT ); Wed, 6 Jul 2016 11:06:34 -0400 Received: from mail-yw0-f181.google.com ([209.85.161.181]:33565 "EHLO mail-yw0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753827AbcGFPGc (ORCPT ); Wed, 6 Jul 2016 11:06:32 -0400 Date: Wed, 6 Jul 2016 11:06:29 -0400 From: Tejun Heo To: aaronlee0817 Cc: axboe@kernel.dk, mlin@kernel.org, shli@kernel.org, linux-kernel@vger.kernel.org, cgroup@vger.kernel.org, jiale0817.li@samsung.com, yanzi.zhang@samsung.com, zhen1.zhang@samsung.com, linux-block@vger.kernel.org Subject: Re: Re: cgroup: Fix split bio been throttled more than once Message-ID: <20160706150629.GA31684@mtj.duckdns.org> References: <77238e99.142c5.155b660564f.Coremail.aaronlee0817@163.com> <20160705222626.GC25394@htj.duckdns.org> <458d1946.12fa6.155c0b80d60.Coremail.aaronlee0817@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <458d1946.12fa6.155c0b80d60.Coremail.aaronlee0817@163.com> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Jul 06, 2016 at 10:58:55PM +0800, aaronlee0817 wrote: > >But that said, can't we just copy BIO_THROTLED while splitting? > > In my opinion， copying BIO_THROTLED while splitting doesn't work > with this, because, the bio within the limit will not set BIO_THROTLED > but will be split, and back to call generic_make_request(), and will be > count twice. I see. It's just a bit weird that we're marking this from clone site when it's an issue which is specific to throttling. The thing is depending on how bio clone is used, it could misbehave in the other direction (bio not accounted at all). What we want to know is whether a bio has been previously accounted or not, rather than whether a bio is a result of splitting. I think it'd be better to track that instead. Thanks. -- tejun