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| author | Venkatesh Pallipadi <venki@google.com> | 2010-10-04 17:03:22 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-10-18 20:52:27 +0200 |
| commit | aa483808516ca5cacfa0e5849691f64fec25828e (patch) | |
| tree | 38a1d9f1cb1157bd68dc2475447bacbb4b63c64a /kernel/sched_fair.c | |
| parent | 305e6835e05513406fa12820e40e4a8ecb63743c (diff) | |
| download | blackbird-op-linux-aa483808516ca5cacfa0e5849691f64fec25828e.tar.gz blackbird-op-linux-aa483808516ca5cacfa0e5849691f64fec25828e.zip | |
sched: Remove irq time from available CPU power
The idea was suggested by Peter Zijlstra here:
http://marc.info/?l=linux-kernel&m=127476934517534&w=2
irq time is technically not available to the tasks running on the CPU.
This patch removes irq time from CPU power piggybacking on
sched_rt_avg_update().
Tested this by keeping CPU X busy with a network intensive task having 75%
oa a single CPU irq processing (hard+soft) on a 4-way system. And start seven
cycle soakers on the system. Without this change, there will be two tasks on
each CPU. With this change, there is a single task on irq busy CPU X and
remaining 7 tasks are spread around among other 3 CPUs.
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-8-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched_fair.c')
| -rw-r--r-- | kernel/sched_fair.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index c358d4081b81..74cccfae87a8 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -2275,7 +2275,13 @@ unsigned long scale_rt_power(int cpu) u64 total, available; total = sched_avg_period() + (rq->clock - rq->age_stamp); - available = total - rq->rt_avg; + + if (unlikely(total < rq->rt_avg)) { + /* Ensures that power won't end up being negative */ + available = 0; + } else { + available = total - rq->rt_avg; + } if (unlikely((s64)total < SCHED_LOAD_SCALE)) total = SCHED_LOAD_SCALE; |
