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From: Joe Korty <joe.korty@ccur.com>
To: Peter Chubb <peter@chubb.wattle.id.au>
Cc: root@chaos.analogic.com, George Anzinger <george@mvista.com>,
	Stephen Hemminger <shemminger@osdl.org>,
	Gabriel Paubert <paubert@iram.es>,
	john stultz <johnstul@us.ibm.com>,
	Linus Torvalds <torvalds@osdl.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@osdl.org>
Subject: [RFC] possible erronous use of tick_usec in do_gettimeofday
Date: Tue, 25 Nov 2003 11:42:38 -0500	[thread overview]
Message-ID: <20031125164237.GA15498@rudolph.ccur.com> (raw)
In-Reply-To: <16289.39801.239846.9369@wombat.chubb.wattle.id.au>

test10's version of do_gettimeofday is using tick_usec which is
defined in terms of USER_HZ not HZ.

Against 2.6.0-test10-bk1.  Compiled, not tested, for comment only.

Joe

--- base/arch/i386/kernel/time.c	2003-11-23 20:31:55.000000000 -0500
+++ new/arch/i386/kernel/time.c	2003-11-25 11:22:38.000000000 -0500
@@ -94,7 +94,7 @@
 {
 	unsigned long seq;
 	unsigned long usec, sec;
-	unsigned long max_ntp_tick = tick_usec - tickadj;
+	unsigned long max_ntp_tick;
 
 	do {
 		unsigned long lost;
@@ -110,13 +110,14 @@
 		 * Better to lose some accuracy than have time go backwards..
 		 */
 		if (unlikely(time_adjust < 0)) {
+			max_ntp_tick = (USEC_PER_SEC / HZ) - tickadj;
 			usec = min(usec, max_ntp_tick);
 
 			if (lost)
 				usec += lost * max_ntp_tick;
 		}
 		else if (unlikely(lost))
-			usec += lost * tick_usec;
+			usec += lost * (USEC_PER_SEC / HZ);
 
 		sec = xtime.tv_sec;
 		usec += (xtime.tv_nsec / 1000);

  parent reply	other threads:[~2003-11-25 16:45 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-10-27 23:44 gettimeofday resolution seriously degraded in test9 Joe Korty
2003-10-28  0:15 ` Stephen Hemminger
2003-10-28  0:29 ` john stultz
2003-10-28  1:17   ` Stephen Hemminger
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                     ` Joe Korty [this message]
2003-11-25 17:13                       ` [RFC] possible erronous use of tick_usec in do_gettimeofday 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] <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>
     [not found]       ` <LVAR.4Mb.3@gated-at.bofh.it>
     [not found]         ` <M4uv.bw.5@gated-at.bofh.it>
     [not found]           ` <M7sx.4et.13@gated-at.bofh.it>
     [not found]             ` <MsGE.8cN.19@gated-at.bofh.it>
     [not found]               ` <MsZZ.c3.5@gated-at.bofh.it>
     [not found]                 ` <Mufp.1YL.15@gated-at.bofh.it>
     [not found]                   ` <VOyG.w9.35@gated-at.bofh.it>
2003-11-28  1:29                     ` [RFC] possible erronous use of tick_usec in do_gettimeofday Andi Kleen

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