Commit 21f0ffaf authored by Trond Myklebust's avatar Trond Myklebust Committed by Trond Myklebust
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SUNRPC: Add basic load balancing to the transport switch 



For now, just count the queue length. It is less accurate than counting
number of bytes queued, but easier to implement.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 44942b4e

include/linux/sunrpc/xprt.h

+1 −0
Original line number Diff line number Diff line
@@ -238,6 +238,7 @@ struct rpc_xprt { 
	/*

	 * Send stuff

	 */

	atomic_long_t		queuelen;

	spinlock_t		transport_lock;	/* lock transport info */

	spinlock_t		reserve_lock;	/* lock slot table */

	spinlock_t		queue_lock;	/* send/receive queue lock */

include/linux/sunrpc/xprtmultipath.h

+2 −0
Original line number Diff line number Diff line
@@ -15,6 +15,8 @@ struct rpc_xprt_switch { 
	struct kref		xps_kref;



	unsigned int		xps_nxprts;

	unsigned int		xps_nactive;

	atomic_long_t		xps_queuelen;

	struct list_head	xps_xprt_list;



	struct net *		xps_net;

net/sunrpc/clnt.c

+37 −3
Original line number Diff line number Diff line
@@ -968,12 +968,46 @@ out: 
}

EXPORT_SYMBOL_GPL(rpc_bind_new_program);



static struct rpc_xprt *

rpc_task_get_xprt(struct rpc_clnt *clnt)

{

	struct rpc_xprt_switch *xps;

	struct rpc_xprt *xprt= xprt_iter_get_next(&clnt->cl_xpi);



	if (!xprt)

		return NULL;

	rcu_read_lock();

	xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);

	atomic_long_inc(&xps->xps_queuelen);

	rcu_read_unlock();

	atomic_long_inc(&xprt->queuelen);



	return xprt;

}



static void

rpc_task_release_xprt(struct rpc_clnt *clnt, struct rpc_xprt *xprt)

{

	struct rpc_xprt_switch *xps;



	atomic_long_dec(&xprt->queuelen);

	rcu_read_lock();

	xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);

	atomic_long_dec(&xps->xps_queuelen);

	rcu_read_unlock();



	xprt_put(xprt);

}



void rpc_task_release_transport(struct rpc_task *task)

{

	struct rpc_xprt *xprt = task->tk_xprt;



	if (xprt) {

		task->tk_xprt = NULL;

		if (task->tk_client)

			rpc_task_release_xprt(task->tk_client, xprt);

		else

			xprt_put(xprt);

	}

}
@@ -983,6 +1017,7 @@ void rpc_task_release_client(struct rpc_task *task) 
{

	struct rpc_clnt *clnt = task->tk_client;



	rpc_task_release_transport(task);

	if (clnt != NULL) {

		/* Remove from client task list */

		spin_lock(&clnt->cl_lock);
@@ -992,14 +1027,13 @@ void rpc_task_release_client(struct rpc_task *task) 


		rpc_release_client(clnt);

	}

	rpc_task_release_transport(task);

}



static

void rpc_task_set_transport(struct rpc_task *task, struct rpc_clnt *clnt)

{

	if (!task->tk_xprt)

		task->tk_xprt = xprt_iter_get_next(&clnt->cl_xpi);

		task->tk_xprt = rpc_task_get_xprt(clnt);

}



static

net/sunrpc/xprtmultipath.c

+19 −1
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ static void xprt_switch_add_xprt_locked(struct rpc_xprt_switch *xps, 
	if (xps->xps_nxprts == 0)

		xps->xps_net = xprt->xprt_net;

	xps->xps_nxprts++;

	xps->xps_nactive++;

}



/**
@@ -62,6 +63,7 @@ static void xprt_switch_remove_xprt_locked(struct rpc_xprt_switch *xps, 
{

	if (unlikely(xprt == NULL))

		return;

	xps->xps_nactive--;

	xps->xps_nxprts--;

	if (xps->xps_nxprts == 0)

		xps->xps_net = NULL;
@@ -317,8 +319,24 @@ struct rpc_xprt *xprt_switch_find_next_entry_roundrobin(struct list_head *head, 
static

struct rpc_xprt *xprt_iter_next_entry_roundrobin(struct rpc_xprt_iter *xpi)

{

	return xprt_iter_next_entry_multiple(xpi,

	struct rpc_xprt_switch *xps = rcu_dereference(xpi->xpi_xpswitch);

	struct rpc_xprt *xprt;

	unsigned long xprt_queuelen;

	unsigned long xps_queuelen;

	unsigned long xps_avglen;



	do {

		xprt = xprt_iter_next_entry_multiple(xpi,

			xprt_switch_find_next_entry_roundrobin);

		if (xprt == NULL)

			break;

		xprt_queuelen = atomic_long_read(&xprt->queuelen);

		if (xprt_queuelen <= 2)

			break;

		xps_queuelen = atomic_long_read(&xps->xps_queuelen);

		xps_avglen = DIV_ROUND_UP(xps_queuelen, xps->xps_nactive);

	} while (xprt_queuelen > xps_avglen);

	return xprt;

}



static

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