diff options
| author | Gautham R Shenoy <ego@in.ibm.com> | 2009-04-14 10:25:35 +0530 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-04-14 11:49:19 +0200 |
| commit | e790fb0ba64bfec158e1219d899cb588275d12ab (patch) | |
| tree | f4eda89681e027cd617881773ab0559d9fced430 /kernel/sched.c | |
| parent | f711f6090a81cbd396b63de90f415d33f563af9b (diff) | |
sched: Nominate a power-efficient ilb in select_nohz_balancer()
The CPU that first goes idle becomes the idle-load-balancer and remains
that until either it picks up a task or till all the CPUs of the system
goes idle.
Optimize this further to allow it to relinquish it's post
once all it's siblings in the power-aware sched_domain go idle, thereby
allowing the whole package-core to go idle. While relinquising the post,
nominate another an idle-load balancer from a semi-idle core/package.
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090414045535.7645.31641.stgit@sofia.in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index b0fefa300b40..36d213bca473 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4414,8 +4414,24 @@ int select_nohz_load_balancer(int stop_tick) /* make me the ilb owner */ if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1) return 1; - } else if (atomic_read(&nohz.load_balancer) == cpu) + } else if (atomic_read(&nohz.load_balancer) == cpu) { + int new_ilb; + + if (!(sched_smt_power_savings || + sched_mc_power_savings)) + return 1; + /* + * Check to see if there is a more power-efficient + * ilb. + */ + new_ilb = find_new_ilb(cpu); + if (new_ilb < nr_cpu_ids && new_ilb != cpu) { + atomic_set(&nohz.load_balancer, -1); + resched_cpu(new_ilb); + return 0; + } return 1; + } } else { if (!cpumask_test_cpu(cpu, nohz.cpu_mask)) return 0; |