From e1255ac77ed688d843b207ebdf2d0e6ca3fc6583 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Tue, 15 Mar 2011 10:14:27 +0000 Subject: Avoid endless loop for vcpu migration. Only call SCHED_OP(pick_cpu) if a previously picked cpu is not suitable on the current iteration of the retry loop. Signed-off-by: Juergen Gross Signed-off-by: Keir Fraser --- xen/common/schedule.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) (limited to 'xen/common/schedule.c') diff --git a/xen/common/schedule.c b/xen/common/schedule.c index e89da7a34b..129abe44e4 100644 --- a/xen/common/schedule.c +++ b/xen/common/schedule.c @@ -395,6 +395,7 @@ static void vcpu_migrate(struct vcpu *v) unsigned long flags; unsigned int old_cpu, new_cpu; spinlock_t *old_lock, *new_lock; + bool_t pick_called = 0; old_cpu = new_cpu = v->processor; for ( ; ; ) @@ -426,14 +427,33 @@ static void vcpu_migrate(struct vcpu *v) spin_lock(old_lock); } - /* Select new CPU. */ old_cpu = v->processor; if ( old_lock == per_cpu(schedule_data, old_cpu).schedule_lock ) { + /* + * If we selected a CPU on the previosu iteration, check if it + * remains suitable for running this vCPU. + */ + if ( pick_called && + (new_lock == per_cpu(schedule_data, new_cpu).schedule_lock) && + cpu_isset(new_cpu, v->cpu_affinity) && + cpu_isset(new_cpu, v->domain->cpupool->cpu_valid) ) + break; + + /* Select a new CPU. */ new_cpu = SCHED_OP(VCPU2OP(v), pick_cpu, v); if ( (new_lock == per_cpu(schedule_data, new_cpu).schedule_lock) && cpu_isset(new_cpu, v->domain->cpupool->cpu_valid) ) break; + pick_called = 1; + } + else + { + /* + * We do not hold the scheduler lock appropriate for this vCPU. + * Thus we cannot select a new CPU on this iteration. Try again. + */ + pick_called = 0; } if ( old_lock != new_lock ) -- cgit v1.2.3