From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Denis Vlasenko <vda.linux@googlemail.com>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH 3/3] delay: add generic udelay(), mdelay() and ssleep()
Date: Fri, 22 Sep 2006 10:36:59 +0100 [thread overview]
Message-ID: <20060922093659.GA8609@flint.arm.linux.org.uk> (raw)
In-Reply-To: <200609221000.33978.vda.linux@googlemail.com>
On Fri, Sep 22, 2006 at 10:00:33AM +0200, Denis Vlasenko wrote:
> * __const_udelay for all arches is removed or renamed to
> ? __const_delay (it did not do microsecond delays anyway)
You never explained this properly - in fact I think your logic is
reversed. Let me remind you of my reply (which afaics never got
a response):
On Wed, Aug 23, 2006 a 09:14:52AM +0100, Russell King wrote:
> On Wed, Aug 23, 2006 at 07:50:24AM +0200, Denis Vlasenko wrote:
> > On Tuesday 22 August 2006 18:55, Russell King wrote:
> > > Please keep a "const" version in ARM. Thanks.
> >
> > Are you talking about this hunk? Why do you want to keep it?
> >
> > I mean, without it udelay(n) will become slower by the time
> > needed for one extra multiply. So we will have maybe
> > udelay(n) ==> udelay(n+0.1).
>
> Why do you think that? With the constant version, the additional
> unnecessary multiply is optimised away by the compiler (since
> constant * constant = constant), so it's actually slightly faster,
> not sligntly slower as you seem to think.
>
> Since the multiply is pure overhead, it's better to get rid of it.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 Serial core
next prev parent reply other threads:[~2006-09-22 9:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200609220955.35826.vda.linux@googlemail.com>
2006-09-22 7:57 ` [PATCH 1/3] delay: s/#include <asm/delay.h>/#include <linux/delay.h>/ Denis Vlasenko
2006-09-22 7:58 ` [PATCH 2/3] delay: remove references to MAX_UDELAY_MS; fix comment Denis Vlasenko
2006-09-22 8:00 ` [PATCH 3/3] delay: add generic udelay(), mdelay() and ssleep() Denis Vlasenko
2006-09-22 9:36 ` Russell King [this message]
2006-09-22 13:46 ` Denis Vlasenko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20060922093659.GA8609@flint.arm.linux.org.uk \
--to=rmk+lkml@arm.linux.org.uk \
--cc=akpm@osdl.org \
--cc=linux-kernel@vger.kernel.org \
--cc=vda.linux@googlemail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox