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authorCon Kolivas <kernel@kolivas.org>2005-11-09 00:38:59 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-09 10:56:32 -0500
commit6dd4a85bb3ee0715415892c8b0f2a9bd08d31ca4 (patch)
treea53890e37a81c4da1d6e6f398aaea66880d4f996 /kernel
parent3b0bd9bc6f3b8a47853d1b1de4520de3878e8941 (diff)
[PATCH] sched: correct smp_nice_bias
The priority biasing was off by mutliplying the total load by the total priority bias and this ruins the ratio of loads between runqueues. This patch should correct the ratios of loads between runqueues to be proportional to overall load. -2nd attempt. From: Dave Kleikamp <shaggy@austin.ibm.com> This patch fixes a divide-by-zero error that I hit on a two-way i386 machine. rq->nr_running is tested to be non-zero, but may change by the time it is used in the division. Saving the value to a local variable ensures that the same value that is checked is used in the division. Signed-off-by: Con Kolivas <kernel@kolivas.org> Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index ec9ea9119b98..502d47c883b6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -972,15 +972,16 @@ void kick_process(task_t *p)
972static inline unsigned long __source_load(int cpu, int type, enum idle_type idle) 972static inline unsigned long __source_load(int cpu, int type, enum idle_type idle)
973{ 973{
974 runqueue_t *rq = cpu_rq(cpu); 974 runqueue_t *rq = cpu_rq(cpu);
975 unsigned long running = rq->nr_running;
975 unsigned long source_load, cpu_load = rq->cpu_load[type-1], 976 unsigned long source_load, cpu_load = rq->cpu_load[type-1],
976 load_now = rq->nr_running * SCHED_LOAD_SCALE; 977 load_now = running * SCHED_LOAD_SCALE;
977 978
978 if (type == 0) 979 if (type == 0)
979 source_load = load_now; 980 source_load = load_now;
980 else 981 else
981 source_load = min(cpu_load, load_now); 982 source_load = min(cpu_load, load_now);
982 983
983 if (idle == NOT_IDLE || rq->nr_running > 1) 984 if (running > 1 || (idle == NOT_IDLE && running))
984 /* 985 /*
985 * If we are busy rebalancing the load is biased by 986 * If we are busy rebalancing the load is biased by
986 * priority to create 'nice' support across cpus. When 987 * priority to create 'nice' support across cpus. When
@@ -989,7 +990,7 @@ static inline unsigned long __source_load(int cpu, int type, enum idle_type idle
989 * prevent idle rebalance from trying to pull tasks from a 990 * prevent idle rebalance from trying to pull tasks from a
990 * queue with only one running task. 991 * queue with only one running task.
991 */ 992 */
992 source_load *= rq->prio_bias; 993 source_load = source_load * rq->prio_bias / running;
993 994
994 return source_load; 995 return source_load;
995} 996}
@@ -1005,16 +1006,17 @@ static inline unsigned long source_load(int cpu, int type)
1005static inline unsigned long __target_load(int cpu, int type, enum idle_type idle) 1006static inline unsigned long __target_load(int cpu, int type, enum idle_type idle)
1006{ 1007{
1007 runqueue_t *rq = cpu_rq(cpu); 1008 runqueue_t *rq = cpu_rq(cpu);
1009 unsigned long running = rq->nr_running;
1008 unsigned long target_load, cpu_load = rq->cpu_load[type-1], 1010 unsigned long target_load, cpu_load = rq->cpu_load[type-1],
1009 load_now = rq->nr_running * SCHED_LOAD_SCALE; 1011 load_now = running * SCHED_LOAD_SCALE;
1010 1012
1011 if (type == 0) 1013 if (type == 0)
1012 target_load = load_now; 1014 target_load = load_now;
1013 else 1015 else
1014 target_load = max(cpu_load, load_now); 1016 target_load = max(cpu_load, load_now);
1015 1017
1016 if (idle == NOT_IDLE || rq->nr_running > 1) 1018 if (running > 1 || (idle == NOT_IDLE && running))
1017 target_load *= rq->prio_bias; 1019 target_load = target_load * rq->prio_bias / running;
1018 1020
1019 return target_load; 1021 return target_load;
1020} 1022}