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| author | Nick Piggin <nickpiggin@yahoo.com.au> | 2005-09-10 00:26:16 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-10 10:06:23 -0700 |
| commit | d6d5cfaf4551aa7713ca6ab73bb77e832602204b (patch) | |
| tree | 2741ff061bca597f26df340feec0a6ee58820e64 /kernel/sched.c | |
| parent | 67f9a619e7460b7d07284a9d0745727a77d3ade6 (diff) | |
| download | lwn-d6d5cfaf4551aa7713ca6ab73bb77e832602204b.tar.gz lwn-d6d5cfaf4551aa7713ca6ab73bb77e832602204b.zip | |
[PATCH] sched: less newidle locking
Similarly to the earlier change in load_balance, only lock the runqueue in
load_balance_newidle if the busiest queue found has a nr_running > 1. This
will reduce frequency of expensive remote runqueue lock aquisitions in the
schedule() path on some workloads.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index c61ee3451a04..930189540f3b 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2104,8 +2104,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq, */ double_lock_balance(this_rq, busiest); nr_moved = move_tasks(this_rq, this_cpu, busiest, - imbalance, sd, idle, - &all_pinned); + imbalance, sd, idle, &all_pinned); spin_unlock(&busiest->lock); /* All tasks on this runqueue were pinned by CPU affinity */ @@ -2200,18 +2199,22 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq, BUG_ON(busiest == this_rq); - /* Attempt to move tasks */ - double_lock_balance(this_rq, busiest); - schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance); - nr_moved = move_tasks(this_rq, this_cpu, busiest, + + nr_moved = 0; + if (busiest->nr_running > 1) { + /* Attempt to move tasks */ + double_lock_balance(this_rq, busiest); + nr_moved = move_tasks(this_rq, this_cpu, busiest, imbalance, sd, NEWLY_IDLE, NULL); + spin_unlock(&busiest->lock); + } + if (!nr_moved) schedstat_inc(sd, lb_failed[NEWLY_IDLE]); else sd->nr_balance_failed = 0; - spin_unlock(&busiest->lock); return nr_moved; out_balanced: |