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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
	Andrew Morton <akpm@osdl.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	mdz@canonical.com, janitor@sternwelten.at
Subject: Re: [PATCH] Use msleep_interruptible for therm_adt7467.c kernel thread
Date: Wed, 29 Sep 2004 14:12:43 +1000	[thread overview]
Message-ID: <1096431162.17114.10.camel@gaston> (raw)
In-Reply-To: <1096421071.14637.6.camel@localhost.localdomain>

On Wed, 2004-09-29 at 11:24, Alan Cox wrote:
> On Mer, 2004-09-29 at 02:58, Herbert Xu wrote:
> > > A more interesting question is why this isn't being driven off a
> > > timer ?
> > 
> > It probably could if the stuff afterwards doesn't sleep.
> 
> schedule_work() ?

I don't like that. I wrote the g5 therm driver (from which this one is
derivated) as a kernel thread because, at least on the g5, I do a lot of
i2c accesses. If I were to do that in schedule_work, I would "hog" keventd
a very long time each time, which is bad.

schedule_work() is always way too much abused in this way, thus beeing
a source of latencies.

Creating my own work queue would have been silly since (at least back
then), it would have meant creating one additional kernel thread on every
CPU... so I decided just to create my own kernel thread and be done with
it.

Now, using a timer and waiting on it would eventually work too, but the
way it is now just works so ...

Ben.



  reply	other threads:[~2004-09-29  4:15 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-09-27 10:25 [PATCH] Use msleep_interruptible for therm_adt7467.c kernel thread Herbert Xu
2004-09-27 12:51 ` Alan Cox
2004-09-29  1:58   ` Herbert Xu
2004-09-29  1:24     ` Alan Cox
2004-09-29  4:12       ` Benjamin Herrenschmidt [this message]
2004-09-29  4:13     ` Benjamin Herrenschmidt
2004-09-30  4:40   ` Andrew Morton

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