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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.