The patch titled
sched: improve smpnice load balancing when load per task imbalanced
has been removed from the -mm tree. Its filename is
sched-improve-smpnice-load-balancing-when-load-per-task.patch
This patch was dropped because it was folded into sched-implement-smpnice.patch
------------------------------------------------------
Subject: sched: improve smpnice load balancing when load per task imbalanced
From: Peter Williams <pwil3058@xxxxxxxxxxxxxx>
Problem:
2 CPU system: if the cpu-0 has two high priority and cpu-1 has one normal
priority task, how can the current code detect this imbalance because
imbalance will be always < busiest_load_per_task and max_load - this_load
will be < 2 * busiest_load_per_task and pwr_move will be <= pwr_now.
Solution:
Modify the assessment of small imbalances to take into account the relative
sizes of busiest_load_per_task and this_load_per_task. This is exploiting
the fact that if the difference between the loads is greater than
busiest_load_per_task and busiest_load_per_task is greater than
this_load_per_task then moving busiest_load_per_task worth of load from
busiest to this will be an improvement in the distribution of weighted
load.
Note: This patch makes no change to load balancing in the case where all
tasks are nice==0.
Signed-off-by: Peter Williams <pwil3058@xxxxxxxxxxxxxx>
Cc: "Chen, Kenneth W" <kenneth.w.chen@xxxxxxxxx>
Cc: "Siddha, Suresh B" <suresh.b.siddha@xxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/sched.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff -puN kernel/sched.c~sched-improve-smpnice-load-balancing-when-load-per-task kernel/sched.c
--- devel/kernel/sched.c~sched-improve-smpnice-load-balancing-when-load-per-task 2006-06-09 15:22:29.000000000 -0700
+++ devel-akpm/kernel/sched.c 2006-06-09 15:22:29.000000000 -0700
@@ -2197,8 +2197,16 @@ find_busiest_group(struct sched_domain *
if (*imbalance < busiest_load_per_task) {
unsigned long pwr_now = 0, pwr_move = 0;
unsigned long tmp;
+ unsigned int imbn = 2;
- if (max_load - this_load >= busiest_load_per_task*2) {
+ if (this_nr_running) {
+ this_load_per_task /= this_nr_running;
+ if (busiest_load_per_task > this_load_per_task)
+ imbn = 1;
+ } else
+ this_load_per_task = SCHED_LOAD_SCALE;
+
+ if (max_load - this_load >= busiest_load_per_task * imbn) {
*imbalance = busiest_load_per_task;
return busiest;
}
@@ -2211,10 +2219,6 @@ find_busiest_group(struct sched_domain *
pwr_now += busiest->cpu_power *
min(busiest_load_per_task, max_load);
- if (this_nr_running)
- this_load_per_task /= this_nr_running;
- else
- this_load_per_task = SCHED_LOAD_SCALE;
pwr_now += this->cpu_power *
min(this_load_per_task, this_load);
pwr_now /= SCHED_LOAD_SCALE;
_
Patches currently in -mm which might be from pwil3058@xxxxxxxxxxxxxx are
origin.patch
sched-implement-smpnice.patch
sched-improve-smpnice-load-balancing-when-load-per-task.patch
sched-modify-move_tasks-to-improve-load-balancing-outcomes.patch
sched-avoid-unnecessarily-moving-highest-priority-task-move_tasks.patch
sched-avoid-unnecessarily-moving-highest-priority-task-move_tasks-fix-2.patch
sched-uninline-task_rq_lock.patch
sched-add-above-background-load-function.patch
pi-futex-scheduler-support-for-pi.patch
pi-futex-rt-mutex-tester-fix.patch
-
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