From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756820Ab3ANPWk (ORCPT ); Mon, 14 Jan 2013 10:22:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37652 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756462Ab3ANPWj (ORCPT ); Mon, 14 Jan 2013 10:22:39 -0500 Date: Mon, 14 Jan 2013 10:22:33 -0500 From: Vivek Goyal To: majianpeng Cc: axboe , linux-kernel , tj Subject: Re: Re: [PATCH] blkcg: Before starting a new slice, firstly count bps/iops limit in func tg_may_dispatch. Message-ID: <20130114152233.GB2380@redhat.com> References: <201301111711251317275@gmail.com> <50F0211D.7040209@kernel.dk> <20130111191726.GB12019@redhat.com> <201301141015538278161@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201301141015538278161@gmail.com> 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 Mon, Jan 14, 2013 at 10:15:58AM +0800, majianpeng wrote: [..] > >Index: linux-2.6/block/blk-throttle.c > >=================================================================== > >--- linux-2.6.orig/block/blk-throttle.c 2012-10-18 01:52:28.000000000 -0400 > >+++ linux-2.6/block/blk-throttle.c 2013-01-14 03:40:41.355731375 -0500 > >@@ -648,8 +648,14 @@ static bool tg_may_dispatch(struct throt > > * If previous slice expired, start a new one otherwise renew/extend > > * existing slice to make sure it is at least throtl_slice interval > > * long since now. > >+ * > >+ * Start a new slice only if there is no bio queued in that direction. > >+ * That bio is waiting to be dispatched and slice needs to be > >+ * extended. It might happen that bio waited to be dispatched but > >+ * workqueue execution got little late it might restart a new slice > >+ * instead of taking all the waited time into account. > > */ > >- if (throtl_slice_used(td, tg, rw)) > >+ if (throtl_slice_used(td, tg, rw) && !tg->nr_queued[rw]) > > throtl_start_new_slice(td, tg, rw); > > else { > > if (time_before(tg->slice_end[rw], jiffies + throtl_slice)) > Hi vivek, > Your patch is ok.But i had a question: > What's condition tg->nr_queued[rw] = 0, but bio is not null? When a new bio is about to be queued in an empty group (look at blk_throtl_bio). At that time, tg->nr_queued[rw] might be 0 if no other bio is already queued. Thanks Vivek