From f1dc237c60a5fdecc83062a28a702193f881cb19 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Fri, 27 May 2016 12:59:33 -0400 Subject: [PATCH] SUNRPC: Reduce latency when send queue is congested Use the low latency transport workqueue to process the task that is next in line on the xprt->sending queue. Signed-off-by: Trond Myklebust --- include/linux/sunrpc/sched.h | 4 ++++ net/sunrpc/sched.c | 43 +++++++++++++++++++++++++++--------- net/sunrpc/xprt.c | 6 +++-- 3 files changed, 41 insertions(+), 12 deletions(-) diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h index ef780b3b5e31..817af0b4385e 100644 --- a/include/linux/sunrpc/sched.h +++ b/include/linux/sunrpc/sched.h @@ -230,6 +230,10 @@ void rpc_wake_up_queued_task(struct rpc_wait_queue *, struct rpc_task *); void rpc_wake_up(struct rpc_wait_queue *); struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *); +struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq, + struct rpc_wait_queue *, + bool (*)(struct rpc_task *, void *), + void *); struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *, bool (*)(struct rpc_task *, void *), void *); diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index a9f786247ffb..9ae588511aaf 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -330,7 +330,8 @@ EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task); * lockless RPC_IS_QUEUED() test) before we've had a chance to test * the RPC_TASK_RUNNING flag. */ -static void rpc_make_runnable(struct rpc_task *task) +static void rpc_make_runnable(struct workqueue_struct *wq, + struct rpc_task *task) { bool need_wakeup = !rpc_test_and_set_running(task); @@ -339,7 +340,7 @@ static void rpc_make_runnable(struct rpc_task *task) return; if (RPC_IS_ASYNC(task)) { INIT_WORK(&task->u.tk_work, rpc_async_schedule); - queue_work(rpciod_workqueue, &task->u.tk_work); + queue_work(wq, &task->u.tk_work); } else wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED); } @@ -408,13 +409,16 @@ void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task, EXPORT_SYMBOL_GPL(rpc_sleep_on_priority); /** - * __rpc_do_wake_up_task - wake up a single rpc_task + * __rpc_do_wake_up_task_on_wq - wake up a single rpc_task + * @wq: workqueue on which to run task * @queue: wait queue * @task: task to be woken up * * Caller must hold queue->lock, and have cleared the task queued flag. */ -static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task) +static void __rpc_do_wake_up_task_on_wq(struct workqueue_struct *wq, + struct rpc_wait_queue *queue, + struct rpc_task *task) { dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n", task->tk_pid, jiffies); @@ -429,7 +433,7 @@ static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task __rpc_remove_wait_queue(queue, task); - rpc_make_runnable(task); + rpc_make_runnable(wq, task); dprintk("RPC: __rpc_wake_up_task done\n"); } @@ -437,15 +441,24 @@ static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task /* * Wake up a queued task while the queue lock is being held */ -static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task) +static void rpc_wake_up_task_on_wq_queue_locked(struct workqueue_struct *wq, + struct rpc_wait_queue *queue, struct rpc_task *task) { if (RPC_IS_QUEUED(task)) { smp_rmb(); if (task->tk_waitqueue == queue) - __rpc_do_wake_up_task(queue, task); + __rpc_do_wake_up_task_on_wq(wq, queue, task); } } +/* + * Wake up a queued task while the queue lock is being held + */ +static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task) +{ + rpc_wake_up_task_on_wq_queue_locked(rpciod_workqueue, queue, task); +} + /* * Wake up a task on a specific queue */ @@ -519,7 +532,8 @@ static struct rpc_task *__rpc_find_next_queued(struct rpc_wait_queue *queue) /* * Wake up the first task on the wait queue. */ -struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue, +struct rpc_task *rpc_wake_up_first_on_wq(struct workqueue_struct *wq, + struct rpc_wait_queue *queue, bool (*func)(struct rpc_task *, void *), void *data) { struct rpc_task *task = NULL; @@ -530,7 +544,7 @@ struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue, task = __rpc_find_next_queued(queue); if (task != NULL) { if (func(task, data)) - rpc_wake_up_task_queue_locked(queue, task); + rpc_wake_up_task_on_wq_queue_locked(wq, queue, task); else task = NULL; } @@ -538,6 +552,15 @@ struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue, return task; } + +/* + * Wake up the first task on the wait queue. + */ +struct rpc_task *rpc_wake_up_first(struct rpc_wait_queue *queue, + bool (*func)(struct rpc_task *, void *), void *data) +{ + return rpc_wake_up_first_on_wq(rpciod_workqueue, queue, func, data); +} EXPORT_SYMBOL_GPL(rpc_wake_up_first); static bool rpc_wake_up_next_func(struct rpc_task *task, void *data) @@ -815,7 +838,7 @@ void rpc_execute(struct rpc_task *task) bool is_async = RPC_IS_ASYNC(task); rpc_set_active(task); - rpc_make_runnable(task); + rpc_make_runnable(rpciod_workqueue, task); if (!is_async) __rpc_execute(task); } diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 71df082b84a9..8313960cac52 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -295,7 +295,8 @@ static void __xprt_lock_write_next(struct rpc_xprt *xprt) if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) return; - if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_func, xprt)) + if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending, + __xprt_lock_write_func, xprt)) return; xprt_clear_locked(xprt); } @@ -324,7 +325,8 @@ static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt) return; if (RPCXPRT_CONGESTED(xprt)) goto out_unlock; - if (rpc_wake_up_first(&xprt->sending, __xprt_lock_write_cong_func, xprt)) + if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending, + __xprt_lock_write_cong_func, xprt)) return; out_unlock: xprt_clear_locked(xprt); -- 2.34.1