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authorIngo Molnar <mingo@elte.hu>2007-10-15 11:00:18 -0400
committerIngo Molnar <mingo@elte.hu>2007-10-15 11:00:18 -0400
commitda84d96176729fb48a8458561e5d8647103168b8 (patch)
tree24c952d956178faa9ac8b5c505513c93a87f4f6b
parente5f32a3856caabe745381279f7f32e3b581b59dc (diff)
sched: reintroduce cache-hot affinity
reintroduce a simplified version of cache-hot/cold scheduling affinity. This improves performance with certain SMP workloads, such as sysbench. Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/sched.h1
-rw-r--r--kernel/sched.c27
-rw-r--r--kernel/sched_fair.c2
-rw-r--r--kernel/sysctl.c8
4 files changed, 38 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8be5b57768c0..fcc9a5ada1a2 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1415,6 +1415,7 @@ extern unsigned int sysctl_sched_wakeup_granularity;
1415extern unsigned int sysctl_sched_batch_wakeup_granularity; 1415extern unsigned int sysctl_sched_batch_wakeup_granularity;
1416extern unsigned int sysctl_sched_child_runs_first; 1416extern unsigned int sysctl_sched_child_runs_first;
1417extern unsigned int sysctl_sched_features; 1417extern unsigned int sysctl_sched_features;
1418extern unsigned int sysctl_sched_migration_cost;
1418#endif 1419#endif
1419 1420
1420extern unsigned int sysctl_sched_compat_yield; 1421extern unsigned int sysctl_sched_compat_yield;
diff --git a/kernel/sched.c b/kernel/sched.c
index 791dd08c692f..089d8b12ab76 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2119,6 +2119,17 @@ static void pull_task(struct rq *src_rq, struct task_struct *p,
2119} 2119}
2120 2120
2121/* 2121/*
2122 * Is this task likely cache-hot:
2123 */
2124static inline int
2125task_hot(struct task_struct *p, unsigned long long now, struct sched_domain *sd)
2126{
2127 s64 delta = now - p->se.exec_start;
2128
2129 return delta < (long long)sysctl_sched_migration_cost;
2130}
2131
2132/*
2122 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? 2133 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2123 */ 2134 */
2124static 2135static
@@ -2139,6 +2150,22 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
2139 if (task_running(rq, p)) 2150 if (task_running(rq, p))
2140 return 0; 2151 return 0;
2141 2152
2153 /*
2154 * Aggressive migration if:
2155 * 1) task is cache cold, or
2156 * 2) too many balance attempts have failed.
2157 */
2158
2159 if (sd->nr_balance_failed > sd->cache_nice_tries) {
2160#ifdef CONFIG_SCHEDSTATS
2161 if (task_hot(p, rq->clock, sd))
2162 schedstat_inc(sd, lb_hot_gained[idle]);
2163#endif
2164 return 1;
2165 }
2166
2167 if (task_hot(p, rq->clock, sd))
2168 return 0;
2142 return 1; 2169 return 1;
2143} 2170}
2144 2171
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index cea1fa32b3f4..a17b785d7000 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -74,6 +74,8 @@ const_debug unsigned int sysctl_sched_batch_wakeup_granularity = 10000000UL;
74 */ 74 */
75const_debug unsigned int sysctl_sched_wakeup_granularity = 10000000UL; 75const_debug unsigned int sysctl_sched_wakeup_granularity = 10000000UL;
76 76
77const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
78
77/************************************************************** 79/**************************************************************
78 * CFS operations on generic schedulable entities: 80 * CFS operations on generic schedulable entities:
79 */ 81 */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 230ca4eb57fe..ec14aa8ac51f 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -277,6 +277,14 @@ static ctl_table kern_table[] = {
277 .mode = 0644, 277 .mode = 0644,
278 .proc_handler = &proc_dointvec, 278 .proc_handler = &proc_dointvec,
279 }, 279 },
280 {
281 .ctl_name = CTL_UNNUMBERED,
282 .procname = "sched_migration_cost",
283 .data = &sysctl_sched_migration_cost,
284 .maxlen = sizeof(unsigned int),
285 .mode = 0644,
286 .proc_handler = &proc_dointvec,
287 },
280#endif 288#endif
281 { 289 {
282 .ctl_name = CTL_UNNUMBERED, 290 .ctl_name = CTL_UNNUMBERED,