From: Ingo Molnar <mingo@elte.hu>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: x86: disable preemption in delay_tsc()
Date: Fri, 16 Nov 2007 08:17:08 +0100 [thread overview]
Message-ID: <20071116071708.GA2103@elte.hu> (raw)
In-Reply-To: <20071115230859.d9ccea20.akpm@linux-foundation.org>
* Andrew Morton <akpm@linux-foundation.org> wrote:
> It sounds like it would work OK. What is the setup cost for a usleep?
> I'd have thought that code which does something like
>
> while (i++ < 1000) {
> foo();
> udelay(1);
> }
>
> would take qiute a bit longer with such a change?
full roundtrip cost ought to be below 10 usecs, depending on the system.
There's no problem doing a non-preemptible udelay up to 10 usecs and we
could use usleep above that.
Ingo
next prev parent reply other threads:[~2007-11-16 7:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200711150400.lAF40lIr020160@hera.kernel.org>
2007-11-16 3:41 ` x86: disable preemption in delay_tsc() Arjan van de Ven
2007-11-16 3:52 ` Andrew Morton
2007-11-16 6:13 ` Ingo Molnar
2007-11-16 7:08 ` Andrew Morton
2007-11-16 7:17 ` Ingo Molnar [this message]
2007-11-16 7:26 ` Andrew Morton
2007-11-16 8:08 ` Avi Kivity
2007-11-16 8:36 ` Ingo Molnar
2007-11-16 8:47 ` [patch] x86: make delay_tsc() preemptible again Ingo Molnar
2007-11-16 9:39 ` Peter Zijlstra
2007-11-16 10:50 ` Ingo Molnar
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