Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 95f7691d authored by Trond Myklebust's avatar Trond Myklebust
Browse files

SUNRPC: Convert xprt receive queue to use an rbtree 



If the server is slow, we can find ourselves with quite a lot of entries
on the receive queue. Converting the search from an O(n) to O(log(n))
can make a significant difference, particularly since we have to hold
a number of locks while searching.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent bd79bc57

include/linux/sunrpc/xprt.h

+2 −2
Original line number Diff line number Diff line
@@ -85,7 +85,7 @@ struct rpc_rqst { 


	union {

		struct list_head	rq_list;	/* Slot allocation list */

		struct list_head	rq_recv;	/* Receive queue */

		struct rb_node		rq_recv;	/* Receive queue */

	};



	struct list_head	rq_xmit;	/* Send queue */
@@ -260,7 +260,7 @@ struct rpc_xprt { 
						 * backchannel rpc_rqst's */

#endif /* CONFIG_SUNRPC_BACKCHANNEL */



	struct list_head	recv_queue;	/* Receive queue */

	struct rb_root		recv_queue;	/* Receive queue */



	struct {

		unsigned long		bind_count,	/* total number of binds */

net/sunrpc/xprt.c

+82 −11
Original line number Diff line number Diff line
@@ -753,7 +753,7 @@ static void 
xprt_schedule_autodisconnect(struct rpc_xprt *xprt)

	__must_hold(&xprt->transport_lock)

{

	if (list_empty(&xprt->recv_queue) && xprt_has_timer(xprt))

	if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))

		mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);

}
@@ -763,7 +763,7 @@ xprt_init_autodisconnect(struct timer_list *t) 
	struct rpc_xprt *xprt = from_timer(xprt, t, timer);



	spin_lock(&xprt->transport_lock);

	if (!list_empty(&xprt->recv_queue))

	if (!RB_EMPTY_ROOT(&xprt->recv_queue))

		goto out_abort;

	/* Reset xprt->last_used to avoid connect/autodisconnect cycling */

	xprt->last_used = jiffies;
@@ -880,6 +880,75 @@ static void xprt_connect_status(struct rpc_task *task) 
	}

}



enum xprt_xid_rb_cmp {

	XID_RB_EQUAL,

	XID_RB_LEFT,

	XID_RB_RIGHT,

};

static enum xprt_xid_rb_cmp

xprt_xid_cmp(__be32 xid1, __be32 xid2)

{

	if (xid1 == xid2)

		return XID_RB_EQUAL;

	if ((__force u32)xid1 < (__force u32)xid2)

		return XID_RB_LEFT;

	return XID_RB_RIGHT;

}



static struct rpc_rqst *

xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)

{

	struct rb_node *n = xprt->recv_queue.rb_node;

	struct rpc_rqst *req;



	while (n != NULL) {

		req = rb_entry(n, struct rpc_rqst, rq_recv);

		switch (xprt_xid_cmp(xid, req->rq_xid)) {

		case XID_RB_LEFT:

			n = n->rb_left;

			break;

		case XID_RB_RIGHT:

			n = n->rb_right;

			break;

		case XID_RB_EQUAL:

			return req;

		}

	}

	return NULL;

}



static void

xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)

{

	struct rb_node **p = &xprt->recv_queue.rb_node;

	struct rb_node *n = NULL;

	struct rpc_rqst *req;



	while (*p != NULL) {

		n = *p;

		req = rb_entry(n, struct rpc_rqst, rq_recv);

		switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {

		case XID_RB_LEFT:

			p = &n->rb_left;

			break;

		case XID_RB_RIGHT:

			p = &n->rb_right;

			break;

		case XID_RB_EQUAL:

			WARN_ON_ONCE(new != req);

			return;

		}

	}

	rb_link_node(&new->rq_recv, n, p);

	rb_insert_color(&new->rq_recv, &xprt->recv_queue);

}



static void

xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)

{

	rb_erase(&req->rq_recv, &xprt->recv_queue);

}



/**

 * xprt_lookup_rqst - find an RPC request corresponding to an XID

 * @xprt: transport on which the original request was transmitted
@@ -891,8 +960,8 @@ struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid) 
{

	struct rpc_rqst *entry;



	list_for_each_entry(entry, &xprt->recv_queue, rq_recv)

		if (entry->rq_xid == xid) {

	entry = xprt_request_rb_find(xprt, xid);

	if (entry != NULL) {

		trace_xprt_lookup_rqst(xprt, xid, 0);

		entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);

		return entry;
@@ -981,7 +1050,7 @@ xprt_request_enqueue_receive(struct rpc_task *task) 
			sizeof(req->rq_private_buf));



	/* Add request to the receive list */

	list_add_tail(&req->rq_recv, &xprt->recv_queue);

	xprt_request_rb_insert(xprt, req);

	set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);

	spin_unlock(&xprt->queue_lock);
@@ -999,8 +1068,10 @@ xprt_request_enqueue_receive(struct rpc_task *task) 
static void

xprt_request_dequeue_receive_locked(struct rpc_task *task)

{

	struct rpc_rqst *req = task->tk_rqstp;



	if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))

		list_del(&task->tk_rqstp->rq_recv);

		xprt_request_rb_remove(req->rq_xprt, req);

}



/**
@@ -1711,7 +1782,7 @@ static void xprt_init(struct rpc_xprt *xprt, struct net *net) 
	spin_lock_init(&xprt->queue_lock);



	INIT_LIST_HEAD(&xprt->free);

	INIT_LIST_HEAD(&xprt->recv_queue);

	xprt->recv_queue = RB_ROOT;

	INIT_LIST_HEAD(&xprt->xmit_queue);

#if defined(CONFIG_SUNRPC_BACKCHANNEL)

	spin_lock_init(&xprt->bc_pa_lock);