From: Jeff Garzik <jgarzik@pobox.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Fix up riscom8 driver to use work queues instead of task queueing.
Date: Mon, 18 Aug 2003 15:25:30 -0400 [thread overview]
Message-ID: <20030818192529.GC19067@gtf.org> (raw)
In-Reply-To: <Pine.LNX.4.44.0308181210430.5929-100000@home.osdl.org>
On Mon, Aug 18, 2003 at 12:12:19PM -0700, Linus Torvalds wrote:
>
> On Mon, 18 Aug 2003, Jeff Garzik wrote:
> >
> > schedule_work() is _not_ for that. As currently implemented, you have
> > no guarantees that your schedule_work()-initiated work will even
> > begin in this century.
>
> In theory yes. In practice no. schedule_work() tries to wake up the worker
> process immediately, and as such usually gets the work done asap.
>
> But hey, if you want to improve on the drivers, please go wild. I care
> more about "real life working" than "theoretical but doesn't work".
hehe ;-) well,
* I've hit this situation in real life (waiting on a driver doing
error handling, hogging the single shared workqueue on UP). It
actually gets nasty if a bunch of drivers all throw errors at
the same time... (more below)
* re "improve the drivers" -- if you mean "fixing" those hogging the
shared workqueue, I think that's a workqueue API flaw. If you mean
further fix up the drivers you just modified, well... I think
slackness on my part will win there :)
There was talk in another thread about fixing up workqueue to create
a new kernel thread, if one isn't available within five seconds.
That seemed reasonable to me. Another useful addition to workqueue,
for drivers, would be a one-shot thread "runme(func, func_data)" API.
I think a lot of the device driver error handling is more appropriate
to this one-shot API than the current workqueue API. Error handling is
already a slow path, so the overhead of thread creation on each call is
mitigated.
Jeff
next prev parent reply other threads:[~2003-08-18 19:25 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200308181806.h7II6K6D014918@hera.kernel.org>
2003-08-18 18:09 ` Fix up riscom8 driver to use work queues instead of task queueing Jeff Garzik
2003-08-18 18:21 ` Linus Torvalds
2003-08-18 18:28 ` Russell King
2003-08-18 18:47 ` Linus Torvalds
2003-08-18 18:59 ` Russell King
2003-08-18 19:10 ` Linus Torvalds
2003-08-18 18:44 ` Jeff Garzik
2003-08-18 19:12 ` Linus Torvalds
2003-08-18 19:25 ` Jeff Garzik [this message]
2003-08-18 19:36 ` Linus Torvalds
2003-08-18 20:32 ` Andrew Morton
2003-08-18 21:24 ` Jeff Garzik
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