From: Andi Kleen <andi@firstfloor.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Tejun Heo <tj@kernel.org>,
Arjan van de Ven <arjan@linux.intel.com>,
Jens Axboe <jens.axboe@oracle.com>,
Andi Kleen <andi@firstfloor.org>,
awalls@radix.net, linux-kernel@vger.kernel.org, jeff@garzik.org,
mingo@elte.hu, akpm@linux-foundation.org, rusty@rustcorp.com.au,
cl@linux-foundation.org, dhowells@redhat.com, avi@redhat.com,
johannes@sipsolutions.net
Subject: Re: workqueue thing
Date: Tue, 22 Dec 2009 19:07:03 +0100 [thread overview]
Message-ID: <20091222180703.GI10314@basil.fritz.box> (raw)
In-Reply-To: <1261504042.4937.59.camel@laptop>
> I've seen those consume significant amounts of cpu, now I'm not going to
> argue that workqueues are not the best way to consume lots of cpu, but
> the fact is they _are_ used for that.
AFAIK they currently have the following problems:
- Consuming CPU in shared work queues is a bad idea for obvious reasons
(but I don't think anybody does that)
- Single threaded work is well, single threaded and does not scale
and wastes cores.
- Per CPU work queues are bound to each CPU so that the scheduler
cannot properly load balance (so you might end up with over/under
subscribed CPUs)
One reason I liked a more dynamic frame work for this is that it
has the potential to be exposed to user space and allow automatic
work partitioning there based on available cores. User space
has a lot more CPU consumption than the kernel.
I think Grand Central Dispatch does something in this direction.
TBB would probably also benfit
Short term an alternative for the kernel would be also
to generalize the simple framework that is in btrfs.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2009-12-22 18:07 UTC|newest]
Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-18 12:57 Tejun Heo
2009-12-18 12:57 ` [PATCH 01/27] sched: rename preempt_notifiers to sched_notifiers and refactor implementation Tejun Heo
2009-12-18 12:57 ` [PATCH 02/27] sched: refactor try_to_wake_up() Tejun Heo
2009-12-18 12:57 ` [PATCH 03/27] sched: implement __set_cpus_allowed() Tejun Heo
2009-12-18 12:57 ` [PATCH 04/27] sched: make sched_notifiers unconditional Tejun Heo
2009-12-18 12:57 ` [PATCH 05/27] sched: add wakeup/sleep sched_notifiers and allow NULL notifier ops Tejun Heo
2009-12-18 12:57 ` [PATCH 06/27] sched: implement try_to_wake_up_local() Tejun Heo
2009-12-18 12:57 ` [PATCH 07/27] acpi: use queue_work_on() instead of binding workqueue worker to cpu0 Tejun Heo
2009-12-18 12:57 ` [PATCH 08/27] stop_machine: reimplement without using workqueue Tejun Heo
2009-12-18 12:57 ` [PATCH 09/27] workqueue: misc/cosmetic updates Tejun Heo
2009-12-18 12:57 ` [PATCH 10/27] workqueue: merge feature parameters into flags Tejun Heo
2009-12-18 12:57 ` [PATCH 11/27] workqueue: define both bit position and mask for work flags Tejun Heo
2009-12-18 12:57 ` [PATCH 12/27] workqueue: separate out process_one_work() Tejun Heo
2009-12-18 12:57 ` [PATCH 13/27] workqueue: temporarily disable workqueue tracing Tejun Heo
2009-12-18 12:57 ` [PATCH 14/27] workqueue: kill cpu_populated_map Tejun Heo
2009-12-18 12:57 ` [PATCH 15/27] workqueue: update cwq alignement Tejun Heo
2009-12-18 12:57 ` [PATCH 16/27] workqueue: reimplement workqueue flushing using color coded works Tejun Heo
2009-12-18 12:57 ` [PATCH 17/27] workqueue: introduce worker Tejun Heo
2009-12-18 12:57 ` [PATCH 18/27] workqueue: reimplement work flushing using linked works Tejun Heo
2009-12-18 12:58 ` [PATCH 19/27] workqueue: implement per-cwq active work limit Tejun Heo
2009-12-18 12:58 ` [PATCH 20/27] workqueue: reimplement workqueue freeze using max_active Tejun Heo
2009-12-18 12:58 ` [PATCH 21/27] workqueue: introduce global cwq and unify cwq locks Tejun Heo
2009-12-18 12:58 ` [PATCH 22/27] workqueue: implement worker states Tejun Heo
2009-12-18 12:58 ` [PATCH 23/27] workqueue: reimplement CPU hotplugging support using trustee Tejun Heo
2009-12-18 12:58 ` [PATCH 24/27] workqueue: make single thread workqueue shared worker pool friendly Tejun Heo
2009-12-18 12:58 ` [PATCH 25/27] workqueue: use shared worklist and pool all workers per cpu Tejun Heo
2009-12-18 12:58 ` [PATCH 26/27] workqueue: implement concurrency managed dynamic worker pool Tejun Heo
2009-12-18 12:58 ` [PATCH 27/27] workqueue: increase max_active of keventd and kill current_is_keventd() Tejun Heo
2009-12-18 13:00 ` SUBJ: [RFC PATCHSET] concurrency managed workqueue, take#2 Tejun Heo
2009-12-18 13:03 ` Tejun Heo
2009-12-18 13:45 ` workqueue thing Peter Zijlstra
2009-12-18 13:50 ` Andi Kleen
2009-12-18 15:01 ` Arjan van de Ven
2009-12-21 3:19 ` Tejun Heo
2009-12-21 9:17 ` Jens Axboe
2009-12-21 10:35 ` Peter Zijlstra
2009-12-21 11:09 ` Andi Kleen
2009-12-21 11:17 ` Arjan van de Ven
2009-12-21 11:33 ` Andi Kleen
2009-12-21 13:18 ` Tejun Heo
2009-12-21 11:11 ` Arjan van de Ven
2009-12-21 13:22 ` Tejun Heo
2009-12-21 13:53 ` Arjan van de Ven
2009-12-21 14:19 ` Tejun Heo
2009-12-21 15:19 ` Arjan van de Ven
2009-12-22 0:00 ` Tejun Heo
2009-12-22 11:10 ` Peter Zijlstra
2009-12-22 17:20 ` Linus Torvalds
2009-12-22 17:47 ` Peter Zijlstra
2009-12-22 18:07 ` Andi Kleen [this message]
2009-12-22 18:20 ` Peter Zijlstra
2009-12-23 8:17 ` Stijn Devriendt
2009-12-23 8:43 ` Peter Zijlstra
2009-12-23 9:01 ` Stijn Devriendt
2009-12-22 18:28 ` Linus Torvalds
2009-12-23 8:06 ` Johannes Berg
2009-12-23 3:37 ` Tejun Heo
2009-12-23 6:52 ` Herbert Xu
2009-12-23 8:00 ` Steffen Klassert
2009-12-23 8:01 ` [PATCH 0/2] Parallel crypto/IPsec v7 Steffen Klassert
2009-12-23 8:03 ` [PATCH 1/2] padata: generic parallelization/serialization interface Steffen Klassert
2009-12-23 8:04 ` [PATCH 2/2] crypto: pcrypt - Add pcrypt crypto parallelization wrapper Steffen Klassert
2010-01-07 5:39 ` [PATCH 0/2] Parallel crypto/IPsec v7 Herbert Xu
2010-01-16 9:44 ` David Miller
2009-12-18 15:30 ` workqueue thing Linus Torvalds
2009-12-18 15:39 ` Ingo Molnar
2009-12-18 15:39 ` Peter Zijlstra
2009-12-18 15:47 ` Linus Torvalds
2009-12-18 15:53 ` Peter Zijlstra
2009-12-21 3:04 ` Tejun Heo
2009-12-21 9:22 ` Peter Zijlstra
2009-12-21 13:30 ` Tejun Heo
2009-12-21 14:26 ` Peter Zijlstra
2009-12-21 23:50 ` Tejun Heo
2009-12-22 11:00 ` Peter Zijlstra
2009-12-22 11:03 ` Peter Zijlstra
2009-12-23 3:43 ` Tejun Heo
2009-12-22 11:04 ` Peter Zijlstra
2009-12-23 3:48 ` Tejun Heo
2009-12-22 11:06 ` Peter Zijlstra
2009-12-23 4:18 ` Tejun Heo
2009-12-23 4:42 ` Linus Torvalds
2009-12-23 6:02 ` Ingo Molnar
2009-12-23 6:13 ` Jeff Garzik
2009-12-23 7:53 ` Ingo Molnar
2009-12-23 8:41 ` Peter Zijlstra
2009-12-23 10:25 ` Jeff Garzik
2009-12-23 13:33 ` Stefan Richter
2009-12-23 14:20 ` Mark Brown
2009-12-23 7:09 ` Tejun Heo
2009-12-23 8:01 ` Ingo Molnar
2009-12-23 8:12 ` Ingo Molnar
2009-12-23 8:32 ` Tejun Heo
2009-12-23 8:42 ` Ingo Molnar
2009-12-23 8:27 ` Tejun Heo
2009-12-23 8:37 ` Ingo Molnar
2009-12-23 8:49 ` Tejun Heo
2009-12-23 8:49 ` Ingo Molnar
2009-12-23 9:03 ` Tejun Heo
2009-12-23 13:40 ` Stefan Richter
2009-12-23 13:43 ` Stefan Richter
2009-12-23 8:25 ` Arjan van de Ven
2009-12-23 13:00 ` Stefan Richter
2009-12-23 8:31 ` Stijn Devriendt
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