Re: [PATCH] deinline sleep/delay functions
From: Andrew Morton
Date: Thu Jun 30 2005 - 04:12:56 EST
Russell King <rmk+lkml@xxxxxxxxxxxxxxxx> wrote:
> On Thu, Jun 30, 2005 at 08:52:25AM +0300, Denis Vlasenko wrote:
> > Hi Andrew,
> > Optimizing delay functions for speed is utterly pointless.
> > This patch turns ssleep(n), mdelay(n), udelay(n) and ndelay(n)
> > into functions, thus they generate the smallest possible code
> > at the callsite. Previously they were more or less inlined.
> > Run tested. Saved a few kb off vmlinux.
> > Signed-off-by: Denis Vlasenko <vda@xxxxxxxxxxxxx>
> Rejected-by: Russell King 8)
> The reason is that now we're unable to find out if anyone's doing
> udelay(100000000000000000) which breaks on most architectures.
> There are a number of compile-time checks that your patch has removed
> which catch such things, and as such your patch is not acceptable.
> Some architectures have a lower threshold of acceptability for the
> maximum udelay value, so it's absolutely necessary to keep this.
It removes that check from x86 - other architectures retain it.
I don't recall seeing anyone trigger the check, and it hardly seems worth
adding a "few kb" to vmlinux for it?
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