From: Peter Zijlstra <peterz@infradead.org>
To: Tejun Heo <tj@kernel.org>
Cc: torvalds@linux-foundation.org, awalls@radix.net,
linux-kernel@vger.kernel.org, jeff@garzik.org, mingo@elte.hu,
akpm@linux-foundation.org, jens.axboe@oracle.com,
rusty@rustcorp.com.au, cl@linux-foundation.org,
dhowells@redhat.com, arjan@linux.intel.com, avi@redhat.com,
johannes@sipsolutions.net
Subject: Re: [PATCH 16/19] workqueue: reimplement workqueue flushing using color coded works
Date: Mon, 07 Dec 2009 09:46:02 +0100 [thread overview]
Message-ID: <1260175562.8223.1204.camel@laptop> (raw)
In-Reply-To: <4B196610.7090101@kernel.org>
On Sat, 2009-12-05 at 04:42 +0900, Tejun Heo wrote:
> Hello,
>
> On 12/04/2009 08:46 PM, Peter Zijlstra wrote:
> > Hmm, a long while back I did a PI aware workqueue implementation, that
> > used nested work-lists to implement barriers and flushing.
> >
> > This colour thing seems very prone to starvation when you want to extend
> > worklets with priority.
>
> Can you elaborate how it would be prone to starvation? I was assuming
> flat-priority while designing and implementing this as that was the
> current behavior and never really thought about priority.
A sudden influx of high prio worklets would hold back the completion of
existing worklets, so simply waiting for a particular colour to deplete
is going to last a long while.
The barrier semantics I implemented ensured worklets couldn't cross a
barrier, so if a high prio item got stuck behind a barrier it would
simply elevate the priority of everything before the barrier, and would
complete everything before that barrier before running itself.
This insures progress and thereby guarantees completion of flushes.
next prev parent reply other threads:[~2009-12-07 8:47 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-20 4:46 [PATCHSET] workqueue: prepare for concurrency managed workqueue, take#2 Tejun Heo
2009-11-20 4:46 ` [PATCH 01/19] sched, kvm: fix race condition involving sched_in_preempt_notifers Tejun Heo
2009-11-20 4:46 ` [PATCH 02/19] workqueue: Add debugobjects support Tejun Heo
2009-11-20 4:46 ` [PATCH 03/19] sched: rename preempt_notifier to sched_notifier and always enable it Tejun Heo
2009-11-20 4:46 ` [PATCH 04/19] sched: update sched_notifier and add wakeup/sleep notifications Tejun Heo
2009-11-20 4:46 ` [PATCH 05/19] sched: implement sched_notifier_wake_up_process() Tejun Heo
2009-11-21 12:02 ` Peter Zijlstra
2009-11-20 4:46 ` [PATCH 06/19] scheduler: implement force_cpus_allowed() Tejun Heo
2009-11-21 12:04 ` Peter Zijlstra
2009-11-20 4:46 ` [PATCH 07/19] acpi: use queue_work_on() instead of binding workqueue worker to cpu0 Tejun Heo
2009-11-20 5:09 ` Andrew Morton
2009-11-20 6:24 ` Tejun Heo
2009-11-20 4:46 ` [PATCH 08/19] stop_machine: reimplement without using workqueue Tejun Heo
2009-11-20 4:46 ` [PATCH 09/19] workqueue: misc/cosmetic updates Tejun Heo
2009-11-20 4:46 ` [PATCH 10/19] workqueue: merge feature parametesr into flags Tejun Heo
2009-11-20 4:46 ` [PATCH 11/19] workqueue: update cwq alignement and make one more flag bit available Tejun Heo
2009-11-20 4:46 ` [PATCH 12/19] workqueue: define both bit position and mask for work flags Tejun Heo
2009-11-20 4:46 ` [PATCH 13/19] workqueue: separate out process_one_work() Tejun Heo
2009-11-20 4:46 ` [PATCH 14/19] workqueue: temporarily disable workqueue tracing Tejun Heo
2009-11-20 4:46 ` [PATCH 15/19] workqueue: kill cpu_populated_map Tejun Heo
2009-11-20 8:40 ` Tejun Heo
2009-11-20 4:46 ` [PATCH 16/19] workqueue: reimplement workqueue flushing using color coded works Tejun Heo
2009-12-04 11:46 ` Peter Zijlstra
2009-12-04 19:42 ` Tejun Heo
2009-12-07 8:46 ` Peter Zijlstra [this message]
2009-12-07 10:40 ` Tejun Heo
2009-12-07 10:42 ` Peter Zijlstra
2009-12-07 10:48 ` Tejun Heo
2009-11-20 4:46 ` [PATCH 17/19] workqueue: introduce worker Tejun Heo
2009-11-20 23:44 ` Andy Walls
2009-11-21 2:53 ` Tejun Heo
2009-11-20 4:46 ` [PATCH 18/19] workqueue: reimplement work flushing using linked works Tejun Heo
2009-11-20 4:46 ` [PATCH 19/19] workqueue: reimplement workqueue freeze using cwq->frozen_works queue Tejun Heo
2009-11-21 3:37 ` [PATCHSET] workqueue: prepare for concurrency managed workqueue, take#2 Tejun Heo
2009-11-21 12:07 ` Peter Zijlstra
2009-11-23 1:48 ` Tejun Heo
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