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From: Jonathan Lim <jlim@sgi.com>
To: linux-kernel@vger.kernel.org
Cc: jlan@sgi.com
Subject: [PATCH] Provide u64 version of jiffies_to_usecs() in kernel/tsacct.c
Date: Fri, 28 Dec 2007 13:26:07 -0800 (PST)	[thread overview]
Message-ID: <200712282126.lBSLQ76K042714@sabah.engr.sgi.com> (raw)

It's possible that the values used in and returned from jiffies_to_usecs() are
incorrect because of truncation when variables of type u64 are involved.  So a
function specific to that type is used instead.

Diff'd against: linux/kernel/git/stable/linux-2.6.23.y.git

Signed-off-by: Jonathan Lim <jlim@sgi.com>

--- a/kernel/tsacct.c	2007-12-28 11:58:05.182065029 -0800
+++ b/kernel/tsacct.c	2007-12-28 11:57:37.949013675 -0800
@@ -71,6 +71,17 @@ void bacct_add_tsk(struct taskstats *sta
 
 #ifdef CONFIG_TASK_XACCT
 
+static inline u64 jiffies_to_usecs_u64(const u64 j)
+{
+#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
+	return (USEC_PER_SEC / HZ) * j;
+#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
+	return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
+#else
+	return (j * USEC_PER_SEC) / HZ;
+#endif
+}
+
 #define KB 1024
 #define MB (1024*KB)
 /*
@@ -81,8 +92,8 @@ void xacct_add_tsk(struct taskstats *sta
 	struct mm_struct *mm;
 
 	/* convert pages-jiffies to Mbyte-usec */
-	stats->coremem = jiffies_to_usecs(p->acct_rss_mem1) * PAGE_SIZE / MB;
-	stats->virtmem = jiffies_to_usecs(p->acct_vm_mem1) * PAGE_SIZE / MB;
+	stats->coremem = jiffies_to_usecs_u64(p->acct_rss_mem1) * PAGE_SIZE / MB;
+	stats->virtmem = jiffies_to_usecs_u64(p->acct_vm_mem1) * PAGE_SIZE / MB;
 	mm = get_task_mm(p);
 	if (mm) {
 		/* adjust to KB unit */

             reply	other threads:[~2007-12-28 21:25 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-28 21:26 Jonathan Lim [this message]
2007-12-29  4:52 ` H. Peter Anvin
     [not found] <200801022103.m02L3oL1051764@sabah.engr.sgi.com>
2008-01-03  0:23 ` Andrew Morton
2008-01-03  0:36   ` H. Peter Anvin
2008-01-03  1:06     ` Jonathan Lim
2008-01-03  1:13       ` H. Peter Anvin
     [not found] <no.id>
2008-01-08  1:04 ` Jonathan Lim
2008-02-19 20:52 ` Jonathan Lim
2008-02-19 21:25   ` Randy Dunlap
2008-02-20  2:17     ` Jonathan Lim
2008-02-20  3:52       ` Randy Dunlap
2008-02-25 22:27 ` Jonathan Lim
2008-03-12 23:53   ` Roman Zippel
2008-04-18 21:54 ` Jonathan Lim
2008-02-15  2:27 Jonathan Lim

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