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Commit 40a5f1b1 authored by Trond Myklebust's avatar Trond Myklebust
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SUNRPC: RPC transport queue must be low latency 



rpciod can easily get congested due to the long list of queued rpc_tasks.
Having the receive queue wait in turn for those tasks to complete can
therefore be a bottleneck.

Address the problem by separating the workqueues into:
- rpciod: manages rpc_tasks
- xprtiod: manages transport related work.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 5157b956

include/linux/sunrpc/sched.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -247,6 +247,7 @@ void rpc_show_tasks(struct net *); 
int		rpc_init_mempool(void);

int		rpc_init_mempool(void);

void		rpc_destroy_mempool(void);

void		rpc_destroy_mempool(void);

extern struct workqueue_struct *rpciod_workqueue;

extern struct workqueue_struct *rpciod_workqueue;

extern struct workqueue_struct *xprtiod_workqueue;

void		rpc_prepare_task(struct rpc_task *task);

void		rpc_prepare_task(struct rpc_task *task);





static inline int rpc_wait_for_completion_task(struct rpc_task *task)

static inline int rpc_wait_for_completion_task(struct rpc_task *task)

net/sunrpc/sched.c

+20 −4
Original line number Original line Diff line number Diff line
@@ -54,7 +54,8 @@ static struct rpc_wait_queue delay_queue; 
/*

/*

 * rpciod-related stuff

 * rpciod-related stuff

 */

 */

struct workqueue_struct *rpciod_workqueue;

struct workqueue_struct *rpciod_workqueue __read_mostly;

struct workqueue_struct *xprtiod_workqueue __read_mostly;





/*

/*

 * Disable the timer for a given RPC task. Should be called with

 * Disable the timer for a given RPC task. Should be called with
@@ -1071,10 +1072,22 @@ static int rpciod_start(void) 
	 * Create the rpciod thread and wait for it to start.

	 * Create the rpciod thread and wait for it to start.

	 */

	 */

	dprintk("RPC:       creating workqueue rpciod\n");

	dprintk("RPC:       creating workqueue rpciod\n");

	/* Note: highpri because network receive is latency sensitive */

	wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 0);

	wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);

	if (!wq)

		goto out_failed;

	rpciod_workqueue = wq;

	rpciod_workqueue = wq;

	return rpciod_workqueue != NULL;

	/* Note: highpri because network receive is latency sensitive */

	wq = alloc_workqueue("xprtiod", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);

	if (!wq)

		goto free_rpciod;

	xprtiod_workqueue = wq;

	return 1;

free_rpciod:

	wq = rpciod_workqueue;

	rpciod_workqueue = NULL;

	destroy_workqueue(wq);

out_failed:

	return 0;

}

}





static void rpciod_stop(void)

static void rpciod_stop(void)
@@ -1088,6 +1101,9 @@ static void rpciod_stop(void) 
	wq = rpciod_workqueue;

	wq = rpciod_workqueue;

	rpciod_workqueue = NULL;

	rpciod_workqueue = NULL;

	destroy_workqueue(wq);

	destroy_workqueue(wq);

	wq = xprtiod_workqueue;

	xprtiod_workqueue = NULL;

	destroy_workqueue(wq);

}

}





void

void

net/sunrpc/xprt.c

+4 −4
Original line number Original line Diff line number Diff line
@@ -220,7 +220,7 @@ static void xprt_clear_locked(struct rpc_xprt *xprt) 
		clear_bit(XPRT_LOCKED, &xprt->state);

		clear_bit(XPRT_LOCKED, &xprt->state);

		smp_mb__after_atomic();

		smp_mb__after_atomic();

	} else

	} else

		queue_work(rpciod_workqueue, &xprt->task_cleanup);

		queue_work(xprtiod_workqueue, &xprt->task_cleanup);

}

}





/*

/*
@@ -645,7 +645,7 @@ void xprt_force_disconnect(struct rpc_xprt *xprt) 
	set_bit(XPRT_CLOSE_WAIT, &xprt->state);

	set_bit(XPRT_CLOSE_WAIT, &xprt->state);

	/* Try to schedule an autoclose RPC call */

	/* Try to schedule an autoclose RPC call */

	if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)

	if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)

		queue_work(rpciod_workqueue, &xprt->task_cleanup);

		queue_work(xprtiod_workqueue, &xprt->task_cleanup);

	xprt_wake_pending_tasks(xprt, -EAGAIN);

	xprt_wake_pending_tasks(xprt, -EAGAIN);

	spin_unlock_bh(&xprt->transport_lock);

	spin_unlock_bh(&xprt->transport_lock);

}

}
@@ -672,7 +672,7 @@ void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie) 
	set_bit(XPRT_CLOSE_WAIT, &xprt->state);

	set_bit(XPRT_CLOSE_WAIT, &xprt->state);

	/* Try to schedule an autoclose RPC call */

	/* Try to schedule an autoclose RPC call */

	if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)

	if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)

		queue_work(rpciod_workqueue, &xprt->task_cleanup);

		queue_work(xprtiod_workqueue, &xprt->task_cleanup);

	xprt_wake_pending_tasks(xprt, -EAGAIN);

	xprt_wake_pending_tasks(xprt, -EAGAIN);

out:

out:

	spin_unlock_bh(&xprt->transport_lock);

	spin_unlock_bh(&xprt->transport_lock);
@@ -689,7 +689,7 @@ xprt_init_autodisconnect(unsigned long data) 
	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))

	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))

		goto out_abort;

		goto out_abort;

	spin_unlock(&xprt->transport_lock);

	spin_unlock(&xprt->transport_lock);

	queue_work(rpciod_workqueue, &xprt->task_cleanup);

	queue_work(xprtiod_workqueue, &xprt->task_cleanup);

	return;

	return;

out_abort:

out_abort:

	spin_unlock(&xprt->transport_lock);

	spin_unlock(&xprt->transport_lock);

net/sunrpc/xprtsock.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -1095,7 +1095,7 @@ static void xs_data_ready(struct sock *sk) 
		if (xprt->reestablish_timeout)

		if (xprt->reestablish_timeout)

			xprt->reestablish_timeout = 0;

			xprt->reestablish_timeout = 0;

		if (!test_and_set_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))

		if (!test_and_set_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))

			queue_work(rpciod_workqueue, &transport->recv_worker);

			queue_work(xprtiod_workqueue, &transport->recv_worker);

	}

	}

	read_unlock_bh(&sk->sk_callback_lock);

	read_unlock_bh(&sk->sk_callback_lock);

}

}
@@ -2378,7 +2378,7 @@ static void xs_connect(struct rpc_xprt *xprt, struct rpc_task *task) 
		/* Start by resetting any existing state */

		/* Start by resetting any existing state */

		xs_reset_transport(transport);

		xs_reset_transport(transport);





		queue_delayed_work(rpciod_workqueue,

		queue_delayed_work(xprtiod_workqueue,

				   &transport->connect_worker,

				   &transport->connect_worker,

				   xprt->reestablish_timeout);

				   xprt->reestablish_timeout);

		xprt->reestablish_timeout <<= 1;

		xprt->reestablish_timeout <<= 1;
@@ -2388,7 +2388,7 @@ static void xs_connect(struct rpc_xprt *xprt, struct rpc_task *task) 
			xprt->reestablish_timeout = XS_TCP_MAX_REEST_TO;

			xprt->reestablish_timeout = XS_TCP_MAX_REEST_TO;

	} else {

	} else {

		dprintk("RPC:       xs_connect scheduled xprt %p\n", xprt);

		dprintk("RPC:       xs_connect scheduled xprt %p\n", xprt);

		queue_delayed_work(rpciod_workqueue,

		queue_delayed_work(xprtiod_workqueue,

				   &transport->connect_worker, 0);

				   &transport->connect_worker, 0);

	}

	}

}

}