Messages in this thread Patch in this message | | | Subject | [PATCH] sched: fix exec_start/task_hot on migrated tasks | From | Ben Segall <> | Date | Thu, 15 May 2014 15:59:20 -0700 |
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task_hot checks exec_start on any runnable task, but if it has been migrated since the it last ran, then exec_start is a clock_task from another cpu. If the old cpu's clock_task was sufficiently far ahead of this cpu's then the task will not be considered for another migration until it has run. Instead reset exec_start whenever a task is migrated, since it is presumably no longer hot anyway.
Signed-off-by: Ben Segall <bsegall@google.com> --- kernel/sched/fair.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 28ccf50..9f8dfeb 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4544,6 +4544,9 @@ migrate_task_rq_fair(struct task_struct *p, int next_cpu) atomic_long_add(se->avg.load_avg_contrib, &cfs_rq->removed_load); } + + /* We have migrated, no longer consider this task hot */ + se.exec_start = 0; } #endif /* CONFIG_SMP */
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