diff options
| author | Siddha, Suresh B <suresh.b.siddha@intel.com> | 2005-09-10 09:26:21 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-10 19:06:24 +0200 |
| commit | fa3b6ddc3f4a8eadba52234134cdb59c28b5332d (patch) | |
| tree | 9aa1b8211adb63bb2983be0d4ab2afdfab88e1a3 | |
| parent | [PATCH] sched: use cached variable in sys_sched_yield() (diff) | |
| download | linux-fa3b6ddc3f4a8eadba52234134cdb59c28b5332d.tar.xz linux-fa3b6ddc3f4a8eadba52234134cdb59c28b5332d.zip | |
[PATCH] sched: don't kick ALB in the presence of pinned task
Jack Steiner brought this issue at my OLS talk.
Take a scenario where two tasks are pinned to two HT threads in a physical
package. Idle packages in the system will keep kicking migration_thread on
the busy package with out any success.
We will run into similar scenarios in the presence of CMP/NUMA.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | kernel/sched.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 103f705b245c..1dc29dec38a9 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2125,6 +2125,16 @@ static int load_balance(int this_cpu, runqueue_t *this_rq, if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) { spin_lock(&busiest->lock); + + /* don't kick the migration_thread, if the curr + * task on busiest cpu can't be moved to this_cpu + */ + if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) { + spin_unlock(&busiest->lock); + all_pinned = 1; + goto out_one_pinned; + } + if (!busiest->active_balance) { busiest->active_balance = 1; busiest->push_cpu = this_cpu; @@ -2165,6 +2175,8 @@ out_balanced: schedstat_inc(sd, lb_balanced[idle]); sd->nr_balance_failed = 0; + +out_one_pinned: /* tune up the balancing interval */ if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) || (sd->balance_interval < sd->max_interval)) @@ -2357,7 +2369,8 @@ static void rebalance_tick(int this_cpu, runqueue_t *this_rq, if (j - sd->last_balance >= interval) { if (load_balance(this_cpu, this_rq, sd, idle)) { - /* We've pulled tasks over so either we're no + /* + * We've pulled tasks over so either we're no * longer idle, or one of our SMT siblings is * not idle. */ |