From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751043Ab2AWPVB (ORCPT ); Mon, 23 Jan 2012 10:21:01 -0500 Received: from mx1.redhat.com ([209.132.183.28]:16563 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750754Ab2AWPVA (ORCPT ); Mon, 23 Jan 2012 10:21:00 -0500 Date: Mon, 23 Jan 2012 10:20:55 -0500 From: Vivek Goyal To: Tejun Heo Cc: axboe@kernel.dk, ctalbott@google.com, rni@google.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 08/17] blkcg: shoot down blkio_groups on elevator switch Message-ID: <20120123152055.GD25986@redhat.com> References: <1327202725-3383-1-git-send-email-tj@kernel.org> <1327202725-3383-9-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1327202725-3383-9-git-send-email-tj@kernel.org> 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 Sat, Jan 21, 2012 at 07:25:16PM -0800, Tejun Heo wrote: [..] > diff --git a/block/elevator.c b/block/elevator.c > index 078a491..5e371e4 100644 > --- a/block/elevator.c > +++ b/block/elevator.c > @@ -38,6 +38,7 @@ > #include > > #include "blk.h" > +#include "blk-cgroup.h" > > static DEFINE_SPINLOCK(elv_list_lock); > static LIST_HEAD(elv_list); > @@ -939,6 +940,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) > > spin_lock_irq(q->queue_lock); > ioc_clear_queue(q); > + blkcg_clear_queue(q); What happens to per device rules (per device weight and per device throttling rules)? IIUC, in new scheme of things, upon elevator switch these rules will be gone. I can understand per device weight rules disappearing but what about throttling rules. They are independent of IO scheduler and change of io scheduler should not cause per device throttling rules to get lost. This just gets worse if elevator switch fails and we fall back to old elevator. But now we have lost of the rules as rules were part of blkg.conf and old groups are gone. Thanks Vivek