Date: Fri, 22 Oct 2004 15:49:24 -0700
From: Nishanth Aravamudan <nacc@us.ibm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>, Andrew Morton <akpm@osdl.org>,
       Linus Torvalds <torvalds@osdl.org>,
       Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] PPC32: Fix cpu voltage change delay
Message-ID: <20041022224924.GD11126@us.ibm.com>
References: <16744.45392.781083.565926@cargo.ozlabs.ibm.com> <20041022180117.GA2162@us.ibm.com> <1098484464.11740.77.camel@gaston>
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On Sat, Oct 23, 2004 at 08:34:24AM +1000, Benjamin Herrenschmidt wrote:
> On Sat, 2004-10-23 at 04:01, Nishanth Aravamudan wrote:
> 
> > While looking through the latest bk changelogs, I noticed that you had
> > submitted this patch using msleep(). When I read the comment, though,
> > that you were offsetting the 1 millisecond with a jiffy, I was slightly
> > confused as msleep() is designed to sleep for *at least* the time
> > requested. So if you just use msleep(1) in these cases, you should have
> > the desired effect. msleep() is designed to be independent of HZ (as the
> > timeout is specified in non-jiffy units). Not using the
> > jiffies_to_msecs() macro would remove some extra instructions... The
> > attached patch makes this change (on top of your patch currently in bk7)
> > and also changes the other schedule_timeout()s (at least, those that can
> > be) to msleep.
> 
> No, please leave them as-is at least for now... Last we saw, there was
> a potential issue with schedule_timeout(1) itself not guaranteeing it would
> sleep for an entire jiffie, but only up to the next jiffie...

Ah, ok. Sorry, I was not aware of this issue. Would you mind giving me
more details (off-list, if you'd prefer?).

Thanks,
Nish
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