From: Russell King <rmk@arm.linux.org.uk>
To: Jos Hulzink <josh@stack.nl>
Cc: Linux Kernel Development <linux-kernel@vger.kernel.org>
Subject: Re: udelay and nanosleep questions
Date: Sat, 21 Sep 2002 12:35:46 +0100 [thread overview]
Message-ID: <20020921123546.B27150@flint.arm.linux.org.uk> (raw)
In-Reply-To: <20020921124235.I46546-100000@toad.stack.nl>; from josh@stack.nl on Sat, Sep 21, 2002 at 01:23:10PM +0200
On Sat, Sep 21, 2002 at 01:23:10PM +0200, Jos Hulzink wrote:
> 1) Can I rely on udelay(1) ? i.e. is the resolution high enough to wait at
> least 1 microsecond given it returns normally ? I know the actual
> implementation is platform / cpu dependant, so maybe I should ask: Should
> I be able to rely on udelay(1) ?
udelay() should (note: should) busy wait for at least the requested delay.
It may wait longer though.
Its behaviour in the presence of speedstep type technologies where cpufreq
is not in use is a little undefined; almost anything can happen. However,
with cpufreq in place, we adjust the delay value appropriately so that
a udelay() always sleeps for at least the requested time.
--
Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux
http://www.arm.linux.org.uk/personal/aboutme.html
next prev parent reply other threads:[~2002-09-21 11:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-21 11:23 Jos Hulzink
2002-09-21 11:35 ` Russell King [this message]
2002-09-22 3:51 ` george anzinger
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