diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2012-06-22 15:52:09 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-07-25 04:11:09 +0100 |
| commit | d9a5888a4162d8e06eb909d31cbe5c779c8b67dc (patch) | |
| tree | 3100123bf2562cb0fd8eb721e95b858fe9a70b72 /include | |
| parent | 43fc6bce37ff39ab5010afadf1ea86e7cc9c2b37 (diff) | |
sched/nohz: Rewrite and fix load-avg computation -- again
commit 5167e8d5417bf5c322a703d2927daec727ea40dd upstream.
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>
Link: http://lkml.kernel.org/r/1340373782.18025.74.camel@twins
[ minor edits ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.2: adjust filenames, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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 1c4f3e9b9bc5..5afa2a345ab1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1892,6 +1892,14 @@ 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) { |