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| author | Mike Galbraith <efault@gmx.de> | 2012-06-12 05:18:32 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-07-24 13:53:34 +0200 |
| commit | 970e178985cadbca660feb02f4d2ee3a09f7fdda (patch) | |
| tree | 20f47abb069a5d13940e8cdc48dae5f5563eb59a /include/linux/sched.h | |
| parent | a1cd2b13f754b2c56fb87b8c4912c015f8f57c0c (diff) | |
| download | lwn-970e178985cadbca660feb02f4d2ee3a09f7fdda.tar.gz lwn-970e178985cadbca660feb02f4d2ee3a09f7fdda.zip | |
sched: Improve scalability via 'CPU buddies', which withstand random perturbations
Traversing an entire package is not only expensive, it also leads to tasks
bouncing all over a partially idle and possible quite large package. Fix
that up by assigning a 'buddy' CPU to try to motivate. Each buddy may try
to motivate that one other CPU, if it's busy, tough, it may then try its
SMT sibling, but that's all this optimization is allowed to cost.
Sibling cache buddies are cross-wired to prevent bouncing.
4 socket 40 core + SMT Westmere box, single 30 sec tbench runs, higher is better:
clients 1 2 4 8 16 32 64 128
..........................................................................
pre 30 41 118 645 3769 6214 12233 14312
post 299 603 1211 2418 4697 6847 11606 14557
A nice increase in performance.
Signed-off-by: Mike Galbraith <efault@gmx.de>
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: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1339471112.7352.32.camel@marge.simpson.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 4a1f493e0fef..bc9952991710 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -949,6 +949,7 @@ struct sched_domain { unsigned int smt_gain; int flags; /* See SD_* */ int level; + int idle_buddy; /* cpu assigned to select_idle_sibling() */ /* Runtime fields. */ unsigned long last_balance; /* init to jiffies. units in jiffies */ |