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| author | Peter Zijlstra <peterz@infradead.org> | 2013-08-19 12:41:09 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-09-12 19:14:42 +0200 |
| commit | 6263322c5e8ffdaf5eaaa29e9d02d84a786aa970 (patch) | |
| tree | b11fbbf69279eec14bd80b9c3a30dc19475b5832 /kernel/sched/sched.h | |
| parent | 3b524d60943a2f9ee1194323ff9d5ee01a4d1ce1 (diff) | |
| download | linux-6263322c5e8ffdaf5eaaa29e9d02d84a786aa970.tar.bz2 | |
sched/fair: Rewrite group_imb trigger
Change the group_imb detection from the old 'load-spike' detector to
an actual imbalance detector. We set it from the lower domain balance
pass when it fails to create a balance in the presence of task
affinities.
The advantage is that this should no longer generate the false
positive group_imb conditions generated by transient load spikes from
the normal balancing/bulk-wakeup etc. behaviour.
While I haven't actually observed those they could happen.
I'm not entirely happy with this patch; it somehow feels a little
fragile.
Nor does it solve the biggest issue I have with the group_imb code; it
it still a fragile construct in that once we 'fixed' the imbalance
we'll not detect the group_imb again and could end up re-creating it.
That said, this patch does seem to preserve behaviour for the
described degenerate case. In particular on my 2*6*2 wsm-ep:
taskset -c 3-11 bash -c 'for ((i=0;i<9;i++)) do while :; do :; done & done'
ends up with 9 spinners, each on their own CPU; whereas if you disable
the group_imb code that typically doesn't happen (you'll get one pair
sharing a CPU most of the time).
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-36fpbgl39dv4u51b6yz2ypz5@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/sched.h')
| -rw-r--r-- | kernel/sched/sched.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index b3c5653e1dca..0d7544c3dba7 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -605,6 +605,7 @@ struct sched_group_power { */ unsigned int power, power_orig; unsigned long next_update; + int imbalance; /* XXX unrelated to power but shared group state */ /* * Number of busy cpus in this group. */ |