From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761835Ab0GTWDy (ORCPT ); Tue, 20 Jul 2010 18:03:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38943 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761676Ab0GTWDw (ORCPT ); Tue, 20 Jul 2010 18:03:52 -0400 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <4C2DAEBB.7090607@kernel.org> References: <4C2DAEBB.7090607@kernel.org> <4C2A2688.1020206@kernel.org> <1277759063-24607-1-git-send-email-tj@kernel.org> <1277759063-24607-35-git-send-email-tj@kernel.org> <20100628225513.GB10104@nowhere> <4C299FD8.7030904@kernel.org> <20100629121855.GA5318@nowhere> <4C2A1558.7060007@kernel.org> <20100629155228.GK5318@nowhere> <4C2A176F.1090101@kernel.org> <4C2A220B.8080006@linux.intel.com> <25085.1277847455@redhat.com> To: Tejun Heo Cc: dhowells@redhat.com, Arjan van de Ven , Frederic Weisbecker , torvalds@linux-foundation.org, mingo@elte.hu, linux-kernel@vger.kernel.org, jeff@garzik.org, akpm@linux-foundation.org, rusty@rustcorp.com.au, cl@linux-foundation.org, oleg@redhat.com, axboe@kernel.dk, dwalker@codeaurora.org, stefanr@s5r6.in-berlin.de, florian@mickler.org, andi@firstfloor.org, mst@redhat.com, randy.dunlap@oracle.com, Arjan van de Ven Subject: Re: [PATCHSET] workqueue: implement and use WQ_UNBOUND Date: Tue, 20 Jul 2010 23:01:42 +0100 Message-ID: <31872.1279663302@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tejun Heo wrote: > David, this should work for fscache/slow-work the same way too. That > should relieve your concern, right? Not at the moment. What does this mean: * Unbound workqueues aren't concurrency managed and should be * dispatched to workers immediately. Does this mean you don't get reentrancy guarantees with unbounded work queues? I can't work out how you're achieving it with unbounded queues. I presume with CPU-bound workqueues your doing it by binding the work item to the current CPU still... Btw, how does this fare in an RT system, where work items bound to a CPU can't get executed because their CPU is busy with an RT thread, even though there are other, idle CPUs? > Oh, and Frederic suggested that we would be better off with something based > on tracing API and I agree, so the debugfs thing is currently dropped from > the tree. What do you think? I probably disagree. I just want to be able to cat a file and see the current runqueue state. I don't want to have to write and distribute a special program to do this. Of course, I don't know that much about the tracing API, so cat'ing a file to get the runqueue listed nicely may be possible with that. David