linux-kernel - Re: [PATCH] ASPM: Use msleep instead of cpu

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Message-ID: <20081226182702.GA1528@ucw.cz>
Date:	Fri, 26 Dec 2008 19:27:02 +0100
From:	Pavel Machek <pavel@...e.cz>
To:	Matthew Wilcox <matthew@....cx>
Cc:	Andrew Patterson <andrew.patterson@...com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	shaohua.li@...el.com
Subject: Re: [PATCH] ASPM: Use msleep instead of cpu_relax during link
	retraining

On Thu 2008-12-25 16:24:27, Matthew Wilcox wrote:
> On Thu, Dec 25, 2008 at 08:01:29PM +0100, Pavel Machek wrote:
> > On Mon 2008-12-22 15:11:57, Andrew Patterson wrote:
> > > ASPM: Use msleep instead of cpu_relax during link retraining
> > > 
> > > The cpu_relax() function can be a noop on certain architectures
> > > like IA-64 when CPU threads are disabled, so use msleep instead
> > > during link retraining busy/wait loop.
> > 
> > Author clearly wanted to do a busy loop... why do you think 10msec
> > delay here is acceptable?
> 
> 10ms?  I see a 1ms sleep.

Yes... IIRC msleep will sleep for up-to 1/HZ on non-highres systems.

> Yes, the subsequent test should be of reg16 instead of jiffies.

Thanks.
									Pavel

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