From: William Lee Irwin III <wli@holomorphy.com>
To: Andrew Morton <akpm@osdl.org>
Cc: mingo@elte.hu, davidel@xmailserver.org, jgarzik@pobox.com,
greg@kroah.com, linux-kernel@vger.kernel.org, netdev@oss.sgi.com
Subject: Re: MSEC_TO_JIFFIES is messed up...
Date: Wed, 12 May 2004 13:59:15 -0700 [thread overview]
Message-ID: <20040512205915.GJ1397@holomorphy.com> (raw)
In-Reply-To: <20040512134718.7e55cceb.akpm@osdl.org>
William Lee Irwin III <wli@holomorphy.com> wrote:
>> How about this?
>> #if HZ <= 1000 && !(1000 % HZ)
>> #define MSEC_TO_JIFFIES(m) ((1000/HZ)*(m))
>> #define JIFFIES_TO_MSEC(j) ((j)/(1000/HZ))
>> #elif HZ > 1000 && !(HZ % 1000)
>> #define MSEC_TO_JIFFIES(m) ((m)/(HZ/1000))
>> #define JIFFIES_TO_MSEC(j) ((HZ/1000)*(j))
>> #else
>> #define MSEC_TO_JIFFIES(m) ((HZ*(m) + 999)/1000)
>> #define JIFFIES_TO_MSEC(j) ((1000*(j) + HZ - 1)/HZ)
>> #endif
On Wed, May 12, 2004 at 01:47:18PM -0700, Andrew Morton wrote:
> You promise it's correct and generates good code?
Yes. Changelog:
Optimize the cases where HZ is a divisor of 1000 or vice-versa in
JIFFIES_TO_MSEC() and MSEC_TO_JIFFIES() by allowing the nonvanishing(!)
integral ratios to appear as a parenthesized expressions eligible for
constant folding optimizations.
I'll resend the #ifdef logic against Ingo's latest, which is orthogonal.
-- wli
next prev parent reply other threads:[~2004-05-12 20:59 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20040512020700.6f6aa61f.akpm@osdl.org>
[not found] ` <20040512181903.GG13421@kroah.com>
2004-05-12 18:42 ` MSEC_TO_JIFFIES is messed up Jeff Garzik
2004-05-12 19:33 ` Ingo Molnar
2004-05-12 19:47 ` Valdis.Kletnieks
2004-05-12 19:56 ` Davide Libenzi
2004-05-12 20:07 ` Valdis.Kletnieks
2004-05-12 20:28 ` Ingo Molnar
2004-05-12 20:35 ` Ingo Molnar
2004-05-12 20:50 ` Ingo Molnar
2004-05-12 21:03 ` Valdis.Kletnieks
2004-05-12 21:33 ` Davide Libenzi
2004-05-12 21:07 ` Andrew Morton
2004-05-12 21:17 ` Ingo Molnar
2004-05-12 22:18 ` William Lee Irwin III
2004-05-13 17:38 ` Paul Wagland
2004-05-13 19:11 ` Andrew Morton
2004-05-13 19:19 ` Jeff Garzik
2004-05-13 22:40 ` Andrew Morton
2004-05-13 22:40 ` Andrew Morton
2004-05-13 22:41 ` Andrew Morton
2004-05-13 23:02 ` Jeff Garzik
2004-05-13 19:50 ` Paul Wagland
2004-05-12 23:33 ` Peter Williams
2004-05-12 19:49 ` Davide Libenzi
2004-05-12 20:03 ` Ingo Molnar
2004-05-12 20:18 ` Valdis.Kletnieks
2004-05-12 20:20 ` Andrew Morton
2004-05-12 20:24 ` Jeff Garzik
2004-05-12 20:35 ` Andrew Morton
2004-05-12 20:44 ` Jeff Garzik
2004-05-12 21:03 ` Sridhar Samudrala
2004-05-12 20:32 ` Greg KH
2004-05-12 20:38 ` William Lee Irwin III
2004-05-12 20:47 ` Andrew Morton
2004-05-12 20:58 ` Jeff Garzik
2004-05-12 20:59 ` William Lee Irwin III [this message]
2004-05-12 20:55 ` Ingo Molnar
2004-05-12 21:01 ` Davide Libenzi
2004-05-12 21:12 ` Ingo Molnar
2004-05-12 21:40 ` Davide Libenzi
2004-05-12 21:49 ` Zan Lynx
2004-05-12 22:05 ` Roland Dreier
2004-05-12 21:56 ` Zan Lynx
2004-05-12 21:39 ` J. Bruce Fields
2004-05-12 21:55 ` Andreas Schwab
2004-05-12 22:07 ` J. Bruce Fields
2004-05-16 3:48 ` Chris Wedgwood
2004-05-16 12:10 ` Paul Wagland
2004-05-12 20:17 ` Jeff Garzik
2004-05-12 20:54 ` Bill Rugolsky Jr.
2004-05-12 22:44 ` Bill Rugolsky Jr.
2004-05-12 20:40 Jan Olderdissen
2004-05-12 20:46 ` Jeff Garzik
2004-05-12 20:49 ` Andreas Schwab
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