From: Ingo Molnar <mingo@elte.hu>
the attached patch fixes the SMP balancing problem reported by David
Mosberger. (the 'yield-ing threads do not get spread out properly' bug).
it turns out that we never really spread out tasks in the busy-rebalance
case - contrary to my intention. The most likely incarnation of this
balancing bug is via yield() - but in theory pipe users can be affected
too.
the patch balances more agressively with a slow frequency, on SMP (or
within the same node on NUMA - not between nodes on NUMA).
kernel/sched.c | 3 +--
1 files changed, 1 insertion(+), 2 deletions(-)
diff -puN kernel/sched.c~sched-balance-fix-2.6.0-test3-mm3-A0 kernel/sched.c
--- 25/kernel/sched.c~sched-balance-fix-2.6.0-test3-mm3-A0 2003-08-23 13:57:06.000000000 -0700
+++ 25-akpm/kernel/sched.c 2003-08-23 13:57:06.000000000 -0700
@@ -1144,7 +1144,6 @@ static void rebalance_tick(runqueue_t *t
load_balance(this_rq, idle, cpu_to_node_mask(this_cpu));
spin_unlock(&this_rq->lock);
}
- return;
}
#ifdef CONFIG_NUMA
if (!(j % BUSY_NODE_REBALANCE_TICK))
@@ -1152,7 +1151,7 @@ static void rebalance_tick(runqueue_t *t
#endif
if (!(j % BUSY_REBALANCE_TICK)) {
spin_lock(&this_rq->lock);
- load_balance(this_rq, idle, cpu_to_node_mask(this_cpu));
+ load_balance(this_rq, 0, cpu_to_node_mask(this_cpu));
spin_unlock(&this_rq->lock);
}
}
_