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authorTejun Heo <tj@kernel.org>2010-06-29 10:07:14 +0200
committerTejun Heo <tj@kernel.org>2010-06-29 10:07:14 +0200
commitb71ab8c2025caef8db719aa41af0ed735dc543cd (patch)
tree8cc2c6164acf5fe82e8d8d05924590cb80fe088d /kernel
parente22bee782b3b00bd4534ae9b1c5fb2e8e6573c5c (diff)
workqueue: increase max_active of keventd and kill current_is_keventd()
Define WQ_MAX_ACTIVE and create keventd with max_active set to half of it which means that keventd now can process upto WQ_MAX_ACTIVE / 2 - 1 works concurrently. Unless some combination can result in dependency loop longer than max_active, deadlock won't happen and thus it's unnecessary to check whether current_is_keventd() before trying to schedule a work. Kill current_is_keventd(). (Lockdep annotations are broken. We need lock_map_acquire_read_norecurse()) Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/workqueue.c63
1 files changed, 13 insertions, 50 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 0ad46523b423..4190e84cf995 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2398,7 +2398,6 @@ EXPORT_SYMBOL(schedule_delayed_work_on);
int schedule_on_each_cpu(work_func_t func)
{
int cpu;
- int orig = -1;
struct work_struct *works;
works = alloc_percpu(struct work_struct);
@@ -2407,23 +2406,12 @@ int schedule_on_each_cpu(work_func_t func)
get_online_cpus();
- /*
- * When running in keventd don't schedule a work item on
- * itself. Can just call directly because the work queue is
- * already bound. This also is faster.
- */
- if (current_is_keventd())
- orig = raw_smp_processor_id();
-
for_each_online_cpu(cpu) {
struct work_struct *work = per_cpu_ptr(works, cpu);
INIT_WORK(work, func);
- if (cpu != orig)
- schedule_work_on(cpu, work);
+ schedule_work_on(cpu, work);
}
- if (orig >= 0)
- func(per_cpu_ptr(works, orig));
for_each_online_cpu(cpu)
flush_work(per_cpu_ptr(works, cpu));
@@ -2494,41 +2482,6 @@ int keventd_up(void)
return keventd_wq != NULL;
}
-int current_is_keventd(void)
-{
- bool found = false;
- unsigned int cpu;
-
- /*
- * There no longer is one-to-one relation between worker and
- * work queue and a worker task might be unbound from its cpu
- * if the cpu was offlined. Match all busy workers. This
- * function will go away once dynamic pool is implemented.
- */
- for_each_possible_cpu(cpu) {
- struct global_cwq *gcwq = get_gcwq(cpu);
- struct worker *worker;
- struct hlist_node *pos;
- unsigned long flags;
- int i;
-
- spin_lock_irqsave(&gcwq->lock, flags);
-
- for_each_busy_worker(worker, i, pos, gcwq) {
- if (worker->task == current) {
- found = true;
- break;
- }
- }
-
- spin_unlock_irqrestore(&gcwq->lock, flags);
- if (found)
- break;
- }
-
- return found;
-}
-
static struct cpu_workqueue_struct *alloc_cwqs(void)
{
/*
@@ -2576,6 +2529,16 @@ static void free_cwqs(struct cpu_workqueue_struct *cwqs)
#endif
}
+static int wq_clamp_max_active(int max_active, const char *name)
+{
+ if (max_active < 1 || max_active > WQ_MAX_ACTIVE)
+ printk(KERN_WARNING "workqueue: max_active %d requested for %s "
+ "is out of range, clamping between %d and %d\n",
+ max_active, name, 1, WQ_MAX_ACTIVE);
+
+ return clamp_val(max_active, 1, WQ_MAX_ACTIVE);
+}
+
struct workqueue_struct *__create_workqueue_key(const char *name,
unsigned int flags,
int max_active,
@@ -2585,7 +2548,7 @@ struct workqueue_struct *__create_workqueue_key(const char *name,
struct workqueue_struct *wq;
unsigned int cpu;
- max_active = clamp_val(max_active, 1, INT_MAX);
+ max_active = wq_clamp_max_active(max_active, name);
wq = kzalloc(sizeof(*wq), GFP_KERNEL);
if (!wq)
@@ -3324,6 +3287,6 @@ void __init init_workqueues(void)
spin_unlock_irq(&gcwq->lock);
}
- keventd_wq = create_workqueue("events");
+ keventd_wq = __create_workqueue("events", 0, WQ_DFL_ACTIVE);
BUG_ON(!keventd_wq);
}