From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 02/24] workqueue: defer work to a draining queue Date: Mon, 19 Dec 2011 14:08:41 -0800 Message-ID: <20111219220841.GB6256@google.com> References: <20111217022912.15036.85808.stgit@localhost6.localdomain6> <20111217023318.15036.77389.stgit@localhost6.localdomain6> <20111219214924.GA6256@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-iy0-f174.google.com ([209.85.210.174]:38073 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751610Ab1LSWIq (ORCPT ); Mon, 19 Dec 2011 17:08:46 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Dan Williams Cc: linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org Hello, On Mon, Dec 19, 2011 at 02:01:47PM -0800, Dan Williams wrote: > > Dan, as I replied before, I'm not a big fan of this approach. > > Sorry I must have missed it, I can't seem to find a reply in the archives? Yeah, I can't find it either. I definitely remember writing it. Hmmm... weird. Either I'm finally losing my mind or it didn't get out for some reason. Sorry. :) > > For > > now, I think it would be best to add private wrapper in libsas to > > support deferring unchained work items while draining. > > Ok, a form of this was nak'd by James before [1], but I can try again > with pushing this chained submission checking down into scsi. The issues I see with the proposed change is, * There doesn't seem to be high demand for it. * It isn't implemented the right way - it introduces unnecessary and hidden ordering between chained work items being drained and newly queued unchained ones. We can try to do it properly without affecting new unchained work items but I'm not sure the added complexity is justified given the first issue. I don't think adding a wrapper which defers queueing while draining is going on would be too complex, right? Thank you. -- tejun