Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a25707f3aef9cf68c341eba5960d580f364e4e6f
Commit: a25707f3aef9cf68c341eba5960d580f364e4e6f
Parent: 8ebc91d93669af39dbed50914d7daf457eeb43be
Author: Ingo Molnar <[EMAIL PROTECTED]>
AuthorDate: Mon Oct 15 17:00:03 2007 +0200
Committer: Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Mon Oct 15 17:00:03 2007 +0200
sched: remove precise CPU load
CPU load calculations are statistical anyway, and there's little benefit
from having it calculated on every scheduling event. So remove this code,
it gets rid of a divide from the scheduler wakeup and context-switch
fastpath.
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]>
Signed-off-by: Mike Galbraith <[EMAIL PROTECTED]>
Reviewed-by: Thomas Gleixner <[EMAIL PROTECTED]>
---
kernel/sched.c | 42 +++---
kernel/sched_debug.c |2 --
kernel/sched_fair.c |6 ++
3 files changed, 9 insertions(+), 41 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index d4dabfc..25cc9b2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1972,42 +1972,11 @@ unsigned long nr_active(void)
*/
static void update_cpu_load(struct rq *this_rq)
{
- u64 fair_delta64, exec_delta64, idle_delta64, sample_interval64, tmp64;
unsigned long total_load = this_rq->ls.load.weight;
unsigned long this_load = total_load;
- struct load_stat *ls = &this_rq->ls;
int i, scale;
this_rq->nr_load_updates++;
- if (unlikely(!(sysctl_sched_features & SCHED_FEAT_PRECISE_CPU_LOAD)))
- goto do_avg;
-
- /* Update delta_fair/delta_exec fields first */
- update_curr_load(this_rq);
-
- fair_delta64 = ls->delta_fair + 1;
- ls->delta_fair = 0;
-
- exec_delta64 = ls->delta_exec + 1;
- ls->delta_exec = 0;
-
- sample_interval64 = this_rq->clock - ls->load_update_last;
- ls->load_update_last = this_rq->clock;
-
- if ((s64)sample_interval64 < (s64)TICK_NSEC)
- sample_interval64 = TICK_NSEC;
-
- if (exec_delta64 > sample_interval64)
- exec_delta64 = sample_interval64;
-
- idle_delta64 = sample_interval64 - exec_delta64;
-
- tmp64 = div64_64(SCHED_LOAD_SCALE * exec_delta64, fair_delta64);
- tmp64 = div64_64(tmp64 * exec_delta64, sample_interval64);
-
- this_load = (unsigned long)tmp64;
-
-do_avg:
/* Update our load: */
for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
@@ -2017,7 +1986,13 @@ do_avg:
old_load = this_rq->cpu_load[i];
new_load = this_load;
-
+ /*
+* Round up the averaging division if load is increasing. This
+* prevents us from getting stuck on 9 if the load is 10, for
+* example.
+*/
+ if (new_load > old_load)
+ new_load += scale-1;
this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
}
}
@@ -6484,7 +6459,6 @@ static inline void init_cfs_rq(struct cfs_rq *cfs_rq,
struct rq *rq)
void __init sched_init(void)
{
- u64 now = sched_clock();
int highest_cpu = 0;
int i, j;
@@ -6509,8 +6483,6 @@ void __init sched_init(void)
INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
list_add(&rq->cfs.leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
#endif
- rq->ls.load_update_last = now;
- rq->ls.load_update_start = now;
for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
rq->cpu_load[j] = 0;
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index fd080f6..6b789da 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -145,8 +145,6 @@ static void print_cpu(struct seq_file *m, int cpu)
P(nr_running);
SEQ_printf(m, " .%-30s: %lu\n", "load",
rq->ls.load.weight);
- P(ls.delta_fair);
- P(ls.delta_exec);
P(nr_switches);
P(nr_load_updates);
P(nr_uninterruptible);
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 2138c40..105d57b 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -94,16 +94,14 @@ enum {
SCHED_FEAT_FAIR_SLEEPERS= 1,
SCHED_FEAT_SLEEPER_AVG = 2,
SCHED_FEAT_SLEEPER_LOAD_AVG = 4,
- SCHED_FEAT_PRECISE_CPU_LOAD = 8,
- SCHED_FEAT_START_DEBIT = 16,
- SCHED_FEAT_SKIP_INITIAL = 32,
+ SCHED_FEAT_START_DEBIT = 8,
+ SCHED_FEAT_SKIP_INITIAL = 16,
};
const_debug unsigned int sysctl_sched_featu
