diff options
Diffstat (limited to 'kernel/workqueue.c')
| -rw-r--r-- | kernel/workqueue.c | 34 |
1 files changed, 32 insertions, 2 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 5e63d3b719ae..054774605d2f 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -301,7 +301,11 @@ static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ static LIST_HEAD(workqueues); /* PR: list of all workqueues */ static bool workqueue_freezing; /* PL: have wqs started freezing? */ -static cpumask_var_t wq_unbound_cpumask; /* PL: low level cpumask for all unbound wqs */ +/* PL: allowable cpus for unbound wqs and work items */ +static cpumask_var_t wq_unbound_cpumask; + +/* CPU where unbound work was last round robin scheduled from this CPU */ +static DEFINE_PER_CPU(int, wq_rr_cpu_last); /* the per-cpu worker pools */ static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], @@ -1298,6 +1302,32 @@ static bool is_chained_work(struct workqueue_struct *wq) return worker && worker->current_pwq->wq == wq; } +/* + * When queueing an unbound work item to a wq, prefer local CPU if allowed + * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to + * avoid perturbing sensitive tasks. + */ +static int wq_select_unbound_cpu(int cpu) +{ + int new_cpu; + + if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) + return cpu; + if (cpumask_empty(wq_unbound_cpumask)) + return cpu; + + new_cpu = __this_cpu_read(wq_rr_cpu_last); + new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask); + if (unlikely(new_cpu >= nr_cpu_ids)) { + new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask); + if (unlikely(new_cpu >= nr_cpu_ids)) + return cpu; + } + __this_cpu_write(wq_rr_cpu_last, new_cpu); + + return new_cpu; +} + static void __queue_work(int cpu, struct workqueue_struct *wq, struct work_struct *work) { @@ -1323,7 +1353,7 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, return; retry: if (req_cpu == WORK_CPU_UNBOUND) - cpu = raw_smp_processor_id(); + cpu = wq_select_unbound_cpu(raw_smp_processor_id()); /* pwq which will be used unless @work is executing elsewhere */ if (!(wq->flags & WQ_UNBOUND)) |