From cba6d0d64ee53772b285d0c0c288deefbeaf7775 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 2 Jul 2012 07:08:42 -0700 Subject: Revert "rcu: Move PREEMPT_RCU preemption to switch_to() invocation" This reverts commit 616c310e83b872024271c915c1b9ab505b9efad9. (Move PREEMPT_RCU preemption to switch_to() invocation). Testing by Sasha Levin showed that this can result in deadlock due to invoking the scheduler when one of the runqueue locks is held. Because this commit was simply a performance optimization, revert it. Reported-by: Sasha Levin Signed-off-by: Paul E. McKenney Tested-by: Sasha Levin --- include/linux/sched.h | 10 ---------- 1 file changed, 10 deletions(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 4059c0f33f07..06a4c5f4f55c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1871,22 +1871,12 @@ static inline void rcu_copy_process(struct task_struct *p) INIT_LIST_HEAD(&p->rcu_node_entry); } -static inline void rcu_switch_from(struct task_struct *prev) -{ - if (prev->rcu_read_lock_nesting != 0) - rcu_preempt_note_context_switch(); -} - #else static inline void rcu_copy_process(struct task_struct *p) { } -static inline void rcu_switch_from(struct task_struct *prev) -{ -} - #endif #ifdef CONFIG_SMP -- cgit v1.2.2 From 5167e8d5417bf5c322a703d2927daec727ea40dd Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 22 Jun 2012 15:52:09 +0200 Subject: sched/nohz: Rewrite and fix load-avg computation -- again Thanks to Charles Wang for spotting the defects in the current code: - If we go idle during the sample window -- after sampling, we get a negative bias because we can negate our own sample. - If we wake up during the sample window we get a positive bias because we push the sample to a known active period. So rewrite the entire nohz load-avg muck once again, now adding copious documentation to the code. Reported-and-tested-by: Doug Smythies Reported-and-tested-by: Charles Wang Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Andrew Morton Cc: stable@kernel.org Link: http://lkml.kernel.org/r/1340373782.18025.74.camel@twins [ minor edits ] Signed-off-by: Ingo Molnar --- include/linux/sched.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 4059c0f33f07..20cb7497c59c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1909,6 +1909,14 @@ static inline int set_cpus_allowed_ptr(struct task_struct *p, } #endif +#ifdef CONFIG_NO_HZ +void calc_load_enter_idle(void); +void calc_load_exit_idle(void); +#else +static inline void calc_load_enter_idle(void) { } +static inline void calc_load_exit_idle(void) { } +#endif /* CONFIG_NO_HZ */ + #ifndef CONFIG_CPUMASK_OFFSTACK static inline int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask) { -- cgit v1.2.2