linux-kernel - Re: msleep_interruptible vs msleep

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Date:	Mon, 4 Sep 2006 21:38:26 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	matthieu castet <castet.matthieu@...e.fr>
Cc:	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: Re: msleep_interruptible vs msleep

Am Monday 04 September 2006 21:29 schrieb matthieu castet:
>
> But why if I have a kernel thread that do [1] :
>
> while (true) {
> Do some stuff
> msleep(1000)
> }
>
> the load average is high (near 100%).
>
> and if I use msleep_interruptible the load average is normal.

These are the traditional semantics of incorruptible vs. noninterruptible
sleep. A process that sleep noninterruptible contributes to the load
average but does not consume actual CPU cycles.

I guess you can take that as a hint that the code you're describing
above is a bad thing to do.

> Does the same applies to wait_event_timeout vs
> wait_event_interruptible_timeout ?

yes.

	Arnd <><
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