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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2012-06-22 17:52:09 +0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-07-05 22:58:13 +0400 |
| commit | 5167e8d5417bf5c322a703d2927daec727ea40dd (patch) | |
| tree | b919aac933c104e7c7abc1730da810f60ba3229d /include | |
| parent | 164c33c6adee609b8b9062cce4c10f764d0dce13 (diff) | |
| download | linux-5167e8d5417bf5c322a703d2927daec727ea40dd.tar.xz | |
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 <dsmythies@telus.net>
Reported-and-tested-by: Charles Wang <muming.wq@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/1340373782.18025.74.camel@twins
[ minor edits ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/sched.h | 8 |
1 files changed, 8 insertions, 0 deletions
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) { |