Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753643AbaFXVnp (ORCPT ); Tue, 24 Jun 2014 17:43:45 -0400 Received: from mail-qc0-f175.google.com ([209.85.216.175]:57194 "EHLO mail-qc0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750974AbaFXVno (ORCPT ); Tue, 24 Jun 2014 17:43:44 -0400 Date: Tue, 24 Jun 2014 17:43:40 -0400 From: Tejun Heo To: Shirish Pargaonkar Cc: LKML , vgoyal@redhat.com, Shirish Pargaonkar , axboe@kernel.dk Subject: Re: [PATCH] blkio: Release blkg infrastructure only after last policy is deactivated. Message-ID: <20140624214340.GE14909@htj.dyndns.org> References: <1403549545-6535-1-git-send-email-spargaonkar@suse.com> <20140624210930.GD14909@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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, On Tue, Jun 24, 2014 at 04:37:58PM -0500, Shirish Pargaonkar wrote: > When we start from blk_cleanup_queue(), we put request queue in bypass mode, > drain it (and service queues), and then destroy blkcgs (explicitly) > > When we start from blk_release_queue(), we do not drain first and then > destroy blkcgs. So if we destroy blkcg and then call (implicitly) and > bail out of > blk_drain_queue, we would not have drained the service queues which > is not what we want. I'm not really following you. What do you mean "when we start from blk_release_queue()"? blk_release_queue() is called after the last put which can only follow blk_cleanup_queue() if the queue is fully initialized. The queue is already in bypass mode and fully drained by the time control reaches blk_release_queue(). Module [un]load re-invoking the path doesn't change anything. > I do not see any harm in waiting till end to release blkcgs (as I understand). Well, the harm there is not freeing those blkgs unless all the blkcg policies are unloaded which is usually never on most systems. Thanks. -- tejun -- 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/