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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 <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2016-05-27 12:59:33 -04:00
parent 40a5f1b19b
commit f1dc237c60
3 changed files with 41 additions and 12 deletions
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4
include/linux/sunrpc/sched.h
View File

@ -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 *);

43
net/sunrpc/sched.c
View File

@ -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);
}

6
net/sunrpc/xprt.c
View File

@ -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);