[patch 3/3] tiemrs: cleanup avenrun users

Thomas Gleixner
2009-05-02T19:09:09Z

[-- Attachment #1: calc-load-cleanup-users.patch --]
[-- Type: text/plain, Size: 4010 bytes --]

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.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
fs/proc/loadavg.c | 16 +++++-----------
include/linux/sched.h | 1 +
kernel/timer.c | 47 +++++++++++++++++++++--------------------------
3 files changed, 27 insertions(+), 37 deletions(-)

Index: linux-2.6/fs/proc/loadavg.c
===================================================================
--- linux-2.6.orig/fs/proc/loadavg.c
+++ linux-2.6/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;
+ int 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),
+ 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;
Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h
+++ linux-2.6/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 */
Index: linux-2.6/kernel/timer.c
===================================================================
--- linux-2.6.orig/kernel/timer.c
+++ linux-2.6/kernel/timer.c
@@ -1135,6 +1135,21 @@ static atomic_t avenrun_ticks;
static DEFINE_SPINLOCK(avenrun_lock);
static DEFINE_PER_CPU(int, avenrun_calculate);

+/**
+ * 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)
{
@@ -1432,37 +1447,17 @@ 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);