From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932588Ab0KLQMs (ORCPT ); Fri, 12 Nov 2010 11:12:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:62496 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932535Ab0KLQMr (ORCPT ); Fri, 12 Nov 2010 11:12:47 -0500 Date: Fri, 12 Nov 2010 11:12:20 -0500 From: David Teigland To: Steven Whitehouse Cc: cluster-devel@redhat.com, linux-kernel@vger.kernel.org, Tejun Heo Subject: Re: dlm: Use cmwq for send and receive workqueues Message-ID: <20101112161220.GA11037@redhat.com> References: <1289563949.2419.13.camel@dolmen> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1289563949.2419.13.camel@dolmen> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 12, 2010 at 12:12:29PM +0000, Steven Whitehouse wrote: > > So far as I can tell, there is no reason to use a single-threaded > send workqueue for dlm, since it may need to send to several sockets > concurrently. Both workqueues are set to WQ_MEM_RECLAIM to avoid > any possible deadlocks, WQ_HIGHPRI since locking traffic is highly > latency sensitive (and to avoid a priority inversion wrt GFS2's > glock_workqueue) and WQ_FREEZABLE just in case someone needs to do > that (even though with current cluster infrastructure, it doesn't > make sense as the node will most likely land up ejected from the > cluster) in the future. Thanks, I'll want to do some testing with this, but my test machines do not seem to create more than one dlm_recv workqueue thread (prior to this patch). Have you tested in any cases where many threads end up being created? I've noticed while debugging some many-cpu machines a huge number of dlm_recv threads, which is just excessive. Does this patch address that? > Signed-off-by: Steven Whitehouse > Cc: Tejun Heo > > diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c > index 37a34c2..0893b30 100644 > --- a/fs/dlm/lowcomms.c > +++ b/fs/dlm/lowcomms.c > @@ -1431,14 +1431,16 @@ static void work_stop(void) > static int work_start(void) > { > int error; > - recv_workqueue = create_workqueue("dlm_recv"); > + recv_workqueue = alloc_workqueue("dlm_recv", WQ_MEM_RECLAIM | > + WQ_HIGHPRI | WQ_FREEZEABLE, 0); > error = IS_ERR(recv_workqueue); > if (error) { > log_print("can't start dlm_recv %d", error); > return error; > } > > - send_workqueue = create_singlethread_workqueue("dlm_send"); > + send_workqueue = alloc_workqueue("dlm_send", WQ_MEM_RECLAIM | > + WQ_HIGHPRI | WQ_FREEZEABLE, 0); > error = IS_ERR(send_workqueue); > if (error) { > log_print("can't start dlm_send %d", error); > >