From 2d02494f5a90f2e4b3c4c6acc85ec94674cdc431 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sat, 2 May 2009 20:08:52 +0200
Subject: [PATCH] sched, timers: cleanup avenrun users

avenrun is an rough estimate so we don't have to worry about
consistency of the three avenrun values. Remove the xtime lock
dependency and provide a function to scale the values. Cleanup the
users.

[ Impact: cleanup ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
---
 fs/proc/loadavg.c     | 18 ++++++------------
 include/linux/sched.h |  1 +
 kernel/sched.c        | 15 +++++++++++++++
 kernel/timer.c        | 32 ++++++--------------------------
 4 files changed, 28 insertions(+), 38 deletions(-)

diff --git a/fs/proc/loadavg.c b/fs/proc/loadavg.c
index 9bca39cf99ee..1afa4dd4cae2 100644
--- a/fs/proc/loadavg.c
+++ b/fs/proc/loadavg.c
@@ -12,20 +12,14 @@
 
 static int loadavg_proc_show(struct seq_file *m, void *v)
 {
-	int a, b, c;
-	unsigned long seq;
+	unsigned long avnrun[3];
 
-	do {
-		seq = read_seqbegin(&xtime_lock);
-		a = avenrun[0] + (FIXED_1/200);
-		b = avenrun[1] + (FIXED_1/200);
-		c = avenrun[2] + (FIXED_1/200);
-	} while (read_seqretry(&xtime_lock, seq));
+	get_avenrun(avnrun, FIXED_1/200, 0);
 
-	seq_printf(m, "%d.%02d %d.%02d %d.%02d %ld/%d %d\n",
-		LOAD_INT(a), LOAD_FRAC(a),
-		LOAD_INT(b), LOAD_FRAC(b),
-		LOAD_INT(c), LOAD_FRAC(c),
+	seq_printf(m, "%lu.%02lu %lu.%02lu %lu.%02lu %ld/%d %d\n",
+		LOAD_INT(avnrun[0]), LOAD_FRAC(avnrun[0]),
+		LOAD_INT(avnrun[1]), LOAD_FRAC(avnrun[1]),
+		LOAD_INT(avnrun[2]), LOAD_FRAC(avnrun[2]),
 		nr_running(), nr_threads,
 		task_active_pid_ns(current)->last_pid);
 	return 0;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6eb4892efe45..de7b3b217772 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -116,6 +116,7 @@ struct fs_struct;
  *    11 bit fractions.
  */
 extern unsigned long avenrun[];		/* Load averages */
+extern void get_avenrun(unsigned long *loads, unsigned long offset, int shift);
 
 #define FSHIFT		11		/* nr of bits of precision */
 #define FIXED_1		(1<<FSHIFT)	/* 1.0 as fixed-point */
diff --git a/kernel/sched.c b/kernel/sched.c
index f4eb88153bd1..497c09ba61e7 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2868,6 +2868,21 @@ static unsigned long calc_load_update;
 unsigned long avenrun[3];
 EXPORT_SYMBOL(avenrun);
 
+/**
+ * get_avenrun - get the load average array
+ * @loads:	pointer to dest load array
+ * @offset:	offset to add
+ * @shift:	shift count to shift the result left
+ *
+ * These values are estimates at best, so no need for locking.
+ */
+void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
+{
+	loads[0] = (avenrun[0] + offset) << shift;
+	loads[1] = (avenrun[1] + offset) << shift;
+	loads[2] = (avenrun[2] + offset) << shift;
+}
+
 static unsigned long
 calc_load(unsigned long load, unsigned long exp, unsigned long active)
 {
diff --git a/kernel/timer.c b/kernel/timer.c
index 6a21d7af9620..a26ed294f938 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1356,37 +1356,17 @@ int do_sysinfo(struct sysinfo *info)
 {
 	unsigned long mem_total, sav_total;
 	unsigned int mem_unit, bitcount;
-	unsigned long seq;
+	struct timespec tp;
 
 	memset(info, 0, sizeof(struct sysinfo));
 
-	do {
-		struct timespec tp;
-		seq = read_seqbegin(&xtime_lock);
-
-		/*
-		 * This is annoying.  The below is the same thing
-		 * posix_get_clock_monotonic() does, but it wants to
-		 * take the lock which we want to cover the loads stuff
-		 * too.
-		 */
-
-		getnstimeofday(&tp);
-		tp.tv_sec += wall_to_monotonic.tv_sec;
-		tp.tv_nsec += wall_to_monotonic.tv_nsec;
-		monotonic_to_bootbased(&tp);
-		if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
-			tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
-			tp.tv_sec++;
-		}
-		info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
+	ktime_get_ts(&tp);
+	monotonic_to_bootbased(&tp);
+	info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
 
-		info->loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
-		info->loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
-		info->loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
+	get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);
 
-		info->procs = nr_threads;
-	} while (read_seqretry(&xtime_lock, seq));
+	info->procs = nr_threads;
 
 	si_meminfo(info);
 	si_swapinfo(info);
-- 
2.34.1