From: Stephen Hemminger <shemminger@osdl.org>
To: john stultz <johnstul@us.ibm.com>
Cc: Joe Korty <joe.korty@ccur.com>,
Linus Torvalds <torvalds@osdl.org>,
lkml <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>
Subject: Re: gettimeofday resolution seriously degraded in test9
Date: Mon, 27 Oct 2003 17:17:38 -0800 [thread overview]
Message-ID: <20031027171738.1f962565.shemminger@osdl.org> (raw)
In-Reply-To: <1067300966.1118.378.camel@cog.beaverton.ibm.com>
Arghh... the patch was being way more agressive than necessary.
tickadj which limits NTP is always 1 (for HZ=1000) so NTP will change
at most 1 us per clock tick. This meant we only had to stop time
for the last us of the interval.
diff -Nru a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
--- a/arch/i386/kernel/time.c Mon Oct 27 17:13:22 2003
+++ b/arch/i386/kernel/time.c Mon Oct 27 17:13:22 2003
@@ -110,8 +110,9 @@
* so make sure not to go into next possible interval.
* Better to lose some accuracy than have time go backwards..
*/
- if (unlikely(time_adjust < 0) && usec > tickadj)
- usec = tickadj;
+ if (unlikely(time_adjust < 0) &&
+ unlikely(usec > tick_usec - tickadj))
+ usec = tick_usec - tickadj;
sec = xtime.tv_sec;
usec += (xtime.tv_nsec / 1000);
next prev parent reply other threads:[~2003-10-28 1:17 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-27 23:44 Joe Korty
2003-10-28 0:15 ` Stephen Hemminger
2003-10-28 0:29 ` john stultz
2003-10-28 1:17 ` Stephen Hemminger [this message]
2003-10-28 11:55 ` Gabriel Paubert
2003-10-28 18:21 ` Stephen Hemminger
2003-10-29 10:07 ` Gabriel Paubert
2003-10-29 19:38 ` Stephen Hemminger
2003-10-29 22:50 ` Peter Chubb
2003-10-30 21:33 ` George Anzinger
2003-10-30 21:52 ` Richard B. Johnson
2003-10-30 22:50 ` Chris Friesen
2003-10-30 23:15 ` Peter Chubb
2003-10-30 23:47 ` George Anzinger
2003-11-25 16:42 ` [RFC] possible erronous use of tick_usec in do_gettimeofday Joe Korty
2003-11-25 17:13 ` Stephen Hemminger
2003-11-25 19:57 ` George Anzinger
2003-11-25 21:12 ` Joe Korty
2003-11-25 23:26 ` George Anzinger
2003-10-30 23:27 ` gettimeofday resolution seriously degraded in test9 George Anzinger
2003-10-30 10:39 ` Gabriel Paubert
[not found] <LphK.2Dl.15@gated-at.bofh.it>
[not found] ` <Lq47.3Go.11@gated-at.bofh.it>
[not found] ` <LqGL.4zF.11@gated-at.bofh.it>
[not found] ` <LAPN.1dU.11@gated-at.bofh.it>
[not found] ` <LGLz.1h2.5@gated-at.bofh.it>
2003-10-28 19:19 ` David Mosberger-Tang
2003-10-28 19:59 ` Stephen Hemminger
2003-10-29 0:19 ` David Mosberger
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