From: Tejun Heo <tj@kernel.org>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: mingo@elte.hu, awalls@radix.net, linux-kernel@vger.kernel.org,
jeff@garzik.org, akpm@linux-foundation.org,
rusty@rustcorp.com.au, cl@linux-foundation.org,
dhowells@redhat.com, arjan@linux.intel.com, oleg@redhat.com,
axboe@kernel.dk
Subject: Re: Overview of concurrency managed workqueue
Date: Wed, 16 Jun 2010 15:39:44 +0200 [thread overview]
Message-ID: <4C18D420.8090008@kernel.org> (raw)
In-Reply-To: <1276695468.3640.19.camel@jlt3.sipsolutions.net>
On 06/16/2010 03:37 PM, Johannes Berg wrote:
>> As multiple execution contexts are available for each wq, deadlocks
>> around execution contexts is much harder to create. The default
>> workqueue, system_wq, has maximum concurrency level of 256 and unless
>> there is a use case which can result in a dependency loop involving
>> more than 254 workers, it won't deadlock.
>
> I see a lot of stuff about the current limitations etc., but nothing
> about code that actually _relies_ on the synchronisation properties of
> the current wqs. We talked about that a long time ago, is it still
> guaranteed that a single-threaded wq will serialise all work put onto
> it? It needs to be, but I don't see you explicitly mentioning it.
Oh yeah, if you have WQ_SINGLE_CPU + max inflight of 1, works on the
wq are fully ordered.
--
tejun
next prev parent reply other threads:[~2010-06-16 13:40 UTC|newest]
Thread overview: 129+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-14 21:37 [PATCHSET] workqueue: concurrency managed workqueue, take#5 Tejun Heo
2010-06-14 21:37 ` [PATCH 01/30] kthread: implement kthread_data() Tejun Heo
2010-06-14 21:37 ` [PATCH 02/30] acpi: use queue_work_on() instead of binding workqueue worker to cpu0 Tejun Heo
2010-06-14 21:37 ` [PATCH 03/30] workqueue: kill RT workqueue Tejun Heo
2010-06-14 21:37 ` [PATCH 04/30] workqueue: misc/cosmetic updates Tejun Heo
2010-06-14 21:37 ` [PATCH 05/30] workqueue: merge feature parameters into flags Tejun Heo
2010-06-14 21:37 ` [PATCH 06/30] workqueue: define masks for work flags and conditionalize STATIC flags Tejun Heo
2010-06-14 21:37 ` [PATCH 07/30] workqueue: separate out process_one_work() Tejun Heo
2010-06-14 21:37 ` [PATCH 08/30] workqueue: temporarily disable workqueue tracing Tejun Heo
2010-06-15 13:29 ` Frederic Weisbecker
2010-06-15 16:37 ` Tejun Heo
2010-06-14 21:37 ` [PATCH 09/30] workqueue: kill cpu_populated_map Tejun Heo
2010-06-14 21:37 ` [PATCH 10/30] workqueue: update cwq alignement Tejun Heo
2010-06-14 21:37 ` [PATCH 11/30] workqueue: reimplement workqueue flushing using color coded works Tejun Heo
2010-06-14 21:37 ` [PATCH 12/30] workqueue: introduce worker Tejun Heo
2010-06-14 21:37 ` [PATCH 13/30] workqueue: reimplement work flushing using linked works Tejun Heo
2010-06-14 21:37 ` [PATCH 14/30] workqueue: implement per-cwq active work limit Tejun Heo
2010-06-14 21:37 ` [PATCH 15/30] workqueue: reimplement workqueue freeze using max_active Tejun Heo
2010-06-14 21:37 ` [PATCH 16/30] workqueue: introduce global cwq and unify cwq locks Tejun Heo
2010-06-14 21:37 ` [PATCH 17/30] workqueue: implement worker states Tejun Heo
2010-06-14 21:37 ` [PATCH 18/30] workqueue: reimplement CPU hotplugging support using trustee Tejun Heo
2010-06-14 21:37 ` [PATCH 19/30] workqueue: make single thread workqueue shared worker pool friendly Tejun Heo
2010-06-14 21:37 ` [PATCH 20/30] workqueue: add find_worker_executing_work() and track current_cwq Tejun Heo
2010-06-14 21:37 ` [PATCH 21/30] workqueue: carry cpu number in work data once execution starts Tejun Heo
2010-06-14 21:37 ` [PATCH 22/30] workqueue: implement WQ_NON_REENTRANT Tejun Heo
2010-06-14 21:37 ` [PATCH 23/30] workqueue: use shared worklist and pool all workers per cpu Tejun Heo
2010-06-14 21:37 ` [PATCH 24/30] workqueue: implement concurrency managed dynamic worker pool Tejun Heo
2010-06-14 21:37 ` [PATCH 25/30] workqueue: increase max_active of keventd and kill current_is_keventd() Tejun Heo
2010-06-14 21:37 ` [PATCH 26/30] workqueue: add system_wq, system_long_wq and system_nrt_wq Tejun Heo
2010-06-14 21:37 ` [PATCH 27/30] workqueue: implement DEBUGFS/workqueue Tejun Heo
2010-06-15 13:54 ` Frederic Weisbecker
2010-06-15 16:42 ` Tejun Heo
2010-06-14 21:37 ` [PATCH 28/30] workqueue: implement several utility APIs Tejun Heo
2010-06-14 21:37 ` [PATCH 29/30] libata: take advantage of cmwq and remove concurrency limitations Tejun Heo
2010-06-14 21:37 ` [PATCH 30/30] async: use workqueue for worker pool Tejun Heo
2010-06-14 21:58 ` [PATCHSET] workqueue: concurrency managed workqueue, take#5 Andrew Morton
2010-06-14 22:17 ` Tejun Heo
2010-06-14 22:31 ` Daniel Walker
2010-06-14 22:33 ` Tejun Heo
2010-06-14 22:35 ` Daniel Walker
2010-06-14 22:44 ` Tejun Heo
2010-06-14 22:49 ` Daniel Walker
2010-06-14 22:52 ` Tejun Heo
2010-06-14 22:35 ` Andrew Morton
2010-06-14 22:43 ` Tejun Heo
2010-06-14 23:06 ` Andrew Morton
2010-06-15 12:53 ` tytso
2010-06-15 16:15 ` [PATCH] SubmittingPatches: add more about patch descriptions Randy Dunlap
2010-06-15 16:33 ` Christoph Lameter
2010-06-15 18:15 ` [PATCHSET] workqueue: concurrency managed workqueue, take#5 Stefan Richter
2010-06-15 19:39 ` Tejun Heo
2010-06-15 1:20 ` Jeff Garzik
2010-06-15 18:25 ` Overview of concurrency managed workqueue Tejun Heo
2010-06-15 18:40 ` Christoph Lameter
2010-06-15 18:44 ` Tejun Heo
2010-06-15 19:43 ` Daniel Walker
2010-06-16 12:10 ` Tejun Heo
2010-06-16 13:27 ` Daniel Walker
2010-06-16 13:30 ` Tejun Heo
2010-06-16 13:41 ` Daniel Walker
2010-06-16 13:45 ` Tejun Heo
2010-06-16 14:05 ` Daniel Walker
2010-06-16 14:15 ` Tejun Heo
2010-06-16 14:34 ` Daniel Walker
2010-06-16 14:50 ` Tejun Heo
2010-06-16 15:11 ` Daniel Walker
2010-06-16 15:50 ` Tejun Heo
2010-06-16 16:30 ` Daniel Walker
2010-06-16 16:55 ` Tejun Heo
2010-06-16 18:22 ` Daniel Walker
2010-06-16 18:46 ` Tejun Heo
2010-06-16 19:20 ` Tejun Heo
2010-06-16 19:46 ` Daniel Walker
2010-06-16 19:58 ` Tejun Heo
2010-06-17 5:29 ` Florian Mickler
2010-06-17 6:21 ` Florian Mickler
2010-06-17 8:28 ` Tejun Heo
2010-06-17 18:03 ` Daniel Walker
2010-06-18 6:36 ` Florian Mickler
2010-06-18 16:38 ` Daniel Walker
2010-06-16 19:36 ` Daniel Walker
2010-06-16 19:52 ` Tejun Heo
2010-06-16 20:19 ` Daniel Walker
2010-06-16 20:24 ` Tejun Heo
2010-06-16 20:40 ` Daniel Walker
2010-06-16 21:41 ` Tejun Heo
2010-06-17 23:15 ` Andrew Morton
2010-06-18 8:03 ` Tejun Heo
2010-06-18 8:22 ` Tejun Heo
2010-06-18 17:29 ` Daniel Walker
2010-06-16 18:31 ` Stefan Richter
2010-06-16 18:41 ` Daniel Walker
2010-06-17 12:01 ` Andy Walls
2010-06-17 16:56 ` Daniel Walker
2010-06-17 23:16 ` Andrew Morton
2010-06-18 7:16 ` Tejun Heo
2010-06-18 7:31 ` Andrew Morton
2010-06-18 8:09 ` Tejun Heo
2010-06-18 17:02 ` Andrew Morton
2010-06-18 17:28 ` Tejun Heo
2010-06-19 15:53 ` [PATCH] kthread: implement kthread_worker Tejun Heo
2010-06-21 20:33 ` Randy Dunlap
2010-06-22 7:31 ` Tejun Heo
2010-06-19 8:38 ` Overview of concurrency managed workqueue Andi Kleen
2010-06-19 8:40 ` Tejun Heo
2010-06-19 8:55 ` Andi Kleen
2010-06-19 9:01 ` Tejun Heo
2010-06-19 9:08 ` Andi Kleen
2010-06-19 9:12 ` Tejun Heo
2010-06-19 9:15 ` Andi Kleen
2010-06-19 9:17 ` Tejun Heo
2010-06-19 9:27 ` Andi Kleen
2010-06-19 9:42 ` Tejun Heo
2010-06-19 12:20 ` Andi Kleen
2010-06-19 12:48 ` Tejun Heo
2010-06-17 22:28 ` Daniel Walker
2010-06-16 6:55 ` Florian Mickler
2010-06-16 12:22 ` Tejun Heo
2010-06-16 13:37 ` Johannes Berg
2010-06-16 13:39 ` Tejun Heo [this message]
2010-06-16 13:42 ` Johannes Berg
2010-06-17 23:14 ` Andrew Morton
2010-06-17 23:25 ` Joel Becker
2010-06-17 23:56 ` Andrew Morton
2010-06-18 7:15 ` Tejun Heo
2010-06-18 7:31 ` Tejun Heo
2010-06-15 18:29 ` [PATCHSET] workqueue: concurrency managed workqueue, take#5 Stefan Richter
2010-06-15 18:40 ` Tejun Heo
2010-06-15 20:29 ` Stefan Richter
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