[tip:sched/core] sched: Introduce SCHED_RESET_ON_FORK scheduling policy flag, fix

From: tip-bot for Mike Galbraith
Date: Wed Jun 17 2009 - 06:33:19 EST


Commit-ID: e53438963eacc5624b61293f64e9f93c71f71198
Gitweb: http://git.kernel.org/tip/e53438963eacc5624b61293f64e9f93c71f71198
Author: Mike Galbraith <efault@xxxxxx>
AuthorDate: Tue, 16 Jun 2009 11:05:08 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 17 Jun 2009 09:01:51 +0200

sched: Introduce SCHED_RESET_ON_FORK scheduling policy flag, fix

Make SCHED_RESET_ON_FORK to DTRT for reniced tasks, and make the
sched_fork() SCHED_RESET_ON_FORK bits a self-contained unlikely
code block.

Signed-off-by: Mike Galbraith <efault@xxxxxx>
Acked-by: Lennart Poettering <lennart@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
LKML-Reference: <1245143108.6038.10.camel@xxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
kernel/sched.c | 41 ++++++++++++++++++++++++-----------------
1 file changed, 24 insertions(+), 17 deletions(-)


---
kernel/sched.c | 39 +++++++++++++++++++++++----------------
1 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 32e6ede..34f9424 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2613,28 +2613,35 @@ void sched_fork(struct task_struct *p, int clone_flags)
set_task_cpu(p, cpu);

/*
- * Revert to default priority/policy on fork if requested. Make sure we
- * do not leak PI boosting priority to the child.
+ * Make sure we do not leak PI boosting priority to the child.
*/
- if (current->sched_reset_on_fork &&
- (p->policy == SCHED_FIFO || p->policy == SCHED_RR))
- p->policy = SCHED_NORMAL;
+ p->prio = current->normal_prio;

- if (current->sched_reset_on_fork &&
- (current->normal_prio < DEFAULT_PRIO))
- p->prio = DEFAULT_PRIO;
- else
- p->prio = current->normal_prio;
+ /*
+ * Revert to default priority/policy on fork if requested.
+ */
+ if (unlikely(p->sched_reset_on_fork)) {
+ if (p->policy == SCHED_FIFO || p->policy == SCHED_RR)
+ p->policy = SCHED_NORMAL;
+
+ if (p->normal_prio < DEFAULT_PRIO)
+ p->prio = DEFAULT_PRIO;
+
+ if (PRIO_TO_NICE(p->static_prio) < 0) {
+ p->static_prio = NICE_TO_PRIO(0);
+ set_load_weight(p);
+ }
+
+ /*
+ * We don't need the reset flag anymore after the fork. It has
+ * fulfilled its duty:
+ */
+ p->sched_reset_on_fork = 0;
+ }

if (!rt_prio(p->prio))
p->sched_class = &fair_sched_class;

- /*
- * We don't need the reset flag anymore after the fork. It has
- * fulfilled its duty:
- */
- p->sched_reset_on_fork = 0;
-
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
if (likely(sched_info_on()))
memset(&p->sched_info, 0, sizeof(p->sched_info));
--
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