diff options
| -rw-r--r-- | xen/common/sched_credit.c | 46 |
1 files changed, 24 insertions, 22 deletions
diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c index d183f2dafa..3465542083 100644 --- a/xen/common/sched_credit.c +++ b/xen/common/sched_credit.c @@ -987,35 +987,37 @@ csched_load_balance(int cpu, struct csched_vcpu *snext) * cause a deadlock if the peer CPU is also load balancing and trying * to lock this CPU. */ - if ( spin_trylock(&per_cpu(schedule_data, peer_cpu).schedule_lock) ) + if ( !spin_trylock(&per_cpu(schedule_data, peer_cpu).schedule_lock) ) { + CSCHED_STAT_CRANK(steal_trylock_failed); + continue; + } - spc = CSCHED_PCPU(peer_cpu); - if ( unlikely(spc == NULL) ) - { - CSCHED_STAT_CRANK(steal_peer_down); - speer = NULL; - } - else - { - speer = csched_runq_steal(spc, cpu, snext->pri); - } - - spin_unlock(&per_cpu(schedule_data, peer_cpu).schedule_lock); - - /* Got one! */ - if ( speer ) - { - CSCHED_STAT_CRANK(vcpu_migrate); - return speer; - } + spc = CSCHED_PCPU(peer_cpu); + if ( unlikely(spc == NULL) ) + { + CSCHED_STAT_CRANK(steal_peer_down); + speer = NULL; + } + else if ( is_idle_vcpu(per_cpu(schedule_data, peer_cpu).curr) ) + { + speer = NULL; } else { - CSCHED_STAT_CRANK(steal_trylock_failed); + /* Try to steal work from an online non-idle CPU. */ + speer = csched_runq_steal(spc, cpu, snext->pri); } - } + spin_unlock(&per_cpu(schedule_data, peer_cpu).schedule_lock); + + /* Got one? */ + if ( speer ) + { + CSCHED_STAT_CRANK(vcpu_migrate); + return speer; + } + } /* Failed to find more important work */ __runq_remove(snext); |