diff options
| -rw-r--r-- | mm/vmstat.c | 51 |
1 files changed, 10 insertions, 41 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c index 5b72a8ad2813..77e42ef388c2 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1352,7 +1352,6 @@ static const struct file_operations proc_vmstat_file_operations = { static struct workqueue_struct *vmstat_wq; static DEFINE_PER_CPU(struct delayed_work, vmstat_work); int sysctl_stat_interval __read_mostly = HZ; -static cpumask_var_t cpu_stat_off; #ifdef CONFIG_PROC_FS static void refresh_vm_stats(struct work_struct *work) @@ -1421,24 +1420,10 @@ static void vmstat_update(struct work_struct *w) * Counters were updated so we expect more updates * to occur in the future. Keep on running the * update worker thread. - * If we were marked on cpu_stat_off clear the flag - * so that vmstat_shepherd doesn't schedule us again. */ - if (!cpumask_test_and_clear_cpu(smp_processor_id(), - cpu_stat_off)) { - queue_delayed_work_on(smp_processor_id(), vmstat_wq, + queue_delayed_work_on(smp_processor_id(), vmstat_wq, this_cpu_ptr(&vmstat_work), round_jiffies_relative(sysctl_stat_interval)); - } - } else { - /* - * We did not update any counters so the app may be in - * a mode where it does not cause counter updates. - * We may be uselessly running vmstat_update. - * Defer the checking for differentials to the - * shepherd thread on a different processor. - */ - cpumask_set_cpu(smp_processor_id(), cpu_stat_off); } } @@ -1470,16 +1455,17 @@ static bool need_update(int cpu) return false; } +/* + * Switch off vmstat processing and then fold all the remaining differentials + * until the diffs stay at zero. The function is used by NOHZ and can only be + * invoked when tick processing is not active. + */ void quiet_vmstat(void) { if (system_state != SYSTEM_RUNNING) return; - /* - * If we are already in hands of the shepherd then there - * is nothing for us to do here. - */ - if (cpumask_test_and_set_cpu(smp_processor_id(), cpu_stat_off)) + if (!delayed_work_pending(this_cpu_ptr(&vmstat_work))) return; if (!need_update(smp_processor_id())) @@ -1494,7 +1480,6 @@ void quiet_vmstat(void) refresh_cpu_vm_stats(false); } - /* * Shepherd worker thread that checks the * differentials of processors that have their worker @@ -1511,20 +1496,11 @@ static void vmstat_shepherd(struct work_struct *w) get_online_cpus(); /* Check processors whose vmstat worker threads have been disabled */ - for_each_cpu(cpu, cpu_stat_off) { + for_each_online_cpu(cpu) { struct delayed_work *dw = &per_cpu(vmstat_work, cpu); - if (need_update(cpu)) { - if (cpumask_test_and_clear_cpu(cpu, cpu_stat_off)) - queue_delayed_work_on(cpu, vmstat_wq, dw, 0); - } else { - /* - * Cancel the work if quiet_vmstat has put this - * cpu on cpu_stat_off because the work item might - * be still scheduled - */ - cancel_delayed_work(dw); - } + if (!delayed_work_pending(dw) && need_update(cpu)) + queue_delayed_work_on(cpu, vmstat_wq, dw, 0); } put_online_cpus(); @@ -1540,10 +1516,6 @@ static void __init start_shepherd_timer(void) INIT_DEFERRABLE_WORK(per_cpu_ptr(&vmstat_work, cpu), vmstat_update); - if (!alloc_cpumask_var(&cpu_stat_off, GFP_KERNEL)) - BUG(); - cpumask_copy(cpu_stat_off, cpu_online_mask); - vmstat_wq = alloc_workqueue("vmstat", WQ_FREEZABLE|WQ_MEM_RECLAIM, 0); schedule_delayed_work(&shepherd, round_jiffies_relative(sysctl_stat_interval)); @@ -1578,16 +1550,13 @@ static int vmstat_cpuup_callback(struct notifier_block *nfb, case CPU_ONLINE_FROZEN: refresh_zone_stat_thresholds(); node_set_state(cpu_to_node(cpu), N_CPU); - cpumask_set_cpu(cpu, cpu_stat_off); break; case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN: cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu)); - cpumask_clear_cpu(cpu, cpu_stat_off); break; case CPU_DOWN_FAILED: case CPU_DOWN_FAILED_FROZEN: - cpumask_set_cpu(cpu, cpu_stat_off); break; case CPU_DEAD: case CPU_DEAD_FROZEN: |