summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJens Axboe <axboe@kernel.dk>2019-12-07 21:06:46 -0700
committerJens Axboe <axboe@kernel.dk>2019-12-10 16:33:22 -0700
commite995d5123ed433e37a8d63ac528737c912592e3d (patch)
tree2e3608cdb19631f901bf40a92adc5e74934cdaf8
parent506d95ff5d6aa0a099a116c49d3884e29801d843 (diff)
io-wq: briefly spin for new work after finishing work
To avoid going to sleep only to get woken shortly thereafter, spin briefly for new work upon completion of work. Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io-wq.c24
-rw-r--r--fs/io-wq.h7
2 files changed, 26 insertions, 5 deletions
diff --git a/fs/io-wq.c b/fs/io-wq.c
index 6b663ddceb42..90c4978781fb 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -491,26 +491,46 @@ next:
} while (1);
}
+static inline void io_worker_spin_for_work(struct io_wqe *wqe)
+{
+ int i = 0;
+
+ while (++i < 1000) {
+ if (io_wqe_run_queue(wqe))
+ break;
+ if (need_resched())
+ break;
+ cpu_relax();
+ }
+}
+
static int io_wqe_worker(void *data)
{
struct io_worker *worker = data;
struct io_wqe *wqe = worker->wqe;
struct io_wq *wq = wqe->wq;
+ bool did_work;
io_worker_start(wqe, worker);
+ did_work = false;
while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
set_current_state(TASK_INTERRUPTIBLE);
+loop:
+ if (did_work)
+ io_worker_spin_for_work(wqe);
spin_lock_irq(&wqe->lock);
if (io_wqe_run_queue(wqe)) {
__set_current_state(TASK_RUNNING);
io_worker_handle_work(worker);
- continue;
+ did_work = true;
+ goto loop;
}
+ did_work = false;
/* drops the lock on success, retry */
if (__io_worker_idle(wqe, worker)) {
__release(&wqe->lock);
- continue;
+ goto loop;
}
spin_unlock_irq(&wqe->lock);
if (signal_pending(current))
diff --git a/fs/io-wq.h b/fs/io-wq.h
index 7c333a28e2a7..fb993b2bd0ef 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -35,7 +35,8 @@ static inline void wq_list_add_tail(struct io_wq_work_node *node,
struct io_wq_work_list *list)
{
if (!list->first) {
- list->first = list->last = node;
+ list->last = node;
+ WRITE_ONCE(list->first, node);
} else {
list->last->next = node;
list->last = node;
@@ -47,7 +48,7 @@ static inline void wq_node_del(struct io_wq_work_list *list,
struct io_wq_work_node *prev)
{
if (node == list->first)
- list->first = node->next;
+ WRITE_ONCE(list->first, node->next);
if (node == list->last)
list->last = prev;
if (prev)
@@ -58,7 +59,7 @@ static inline void wq_node_del(struct io_wq_work_list *list,
#define wq_list_for_each(pos, prv, head) \
for (pos = (head)->first, prv = NULL; pos; prv = pos, pos = (pos)->next)
-#define wq_list_empty(list) ((list)->first == NULL)
+#define wq_list_empty(list) (READ_ONCE((list)->first) == NULL)
#define INIT_WQ_LIST(list) do { \
(list)->first = NULL; \
(list)->last = NULL; \