svn commit: r259659 - in head/sys: nfs rpc

Alexander Motin mav at FreeBSD.org
Fri Dec 20 17:39:08 UTC 2013


Author: mav
Date: Fri Dec 20 17:39:07 2013
New Revision: 259659
URL: http://svnweb.freebsd.org/changeset/base/259659

Log:
  Remove several linear list traversals per request from RPC server code.
  
    Do not insert active ports into pool->sp_active list if they are success-
  fully assigned to some thread.  This makes that list include only ports that
  really require attention, and so traversal can be reduced to simple taking
  the first one.
  
    Remove idle thread from pool->sp_idlethreads list when assigning some
  work (port of requests) to it.  That again makes possible to replace list
  traversals with simple taking the first element.

Modified:
  head/sys/nfs/nfs_fha.c
  head/sys/rpc/svc.c
  head/sys/rpc/svc.h

Modified: head/sys/nfs/nfs_fha.c
==============================================================================
--- head/sys/nfs/nfs_fha.c	Fri Dec 20 16:50:52 2013	(r259658)
+++ head/sys/nfs/nfs_fha.c	Fri Dec 20 17:39:07 2013	(r259659)
@@ -289,19 +289,6 @@ fha_hash_entry_add_op(struct fha_hash_en
 		fhe->num_rw += count;
 }
 
-static SVCTHREAD *
-get_idle_thread(SVCPOOL *pool)
-{
-	SVCTHREAD *st;
-
-	LIST_FOREACH(st, &pool->sp_idlethreads, st_ilink) {
-		if (st->st_xprt == NULL && STAILQ_EMPTY(&st->st_reqs))
-			return (st);
-	}
-	return (NULL);
-}
-
-
 /*
  * Get the service thread currently associated with the fhe that is
  * appropriate to handle this operation.
@@ -386,7 +373,7 @@ fha_hash_entry_choose_thread(struct fha_
 			ITRACE_CURPROC(ITRACE_NFS, ITRACE_INFO,
 			    "fha: %p(%d)t", thread, thread->st_reqcount);
 #endif
-		} else if ((thread = get_idle_thread(pool))) {
+		} else if ((thread = LIST_FIRST(&pool->sp_idlethreads))) {
 #if 0
 			ITRACE_CURPROC(ITRACE_NFS, ITRACE_INFO,
 			    "fha: %p(%d)i", thread, thread->st_reqcount);
@@ -418,7 +405,6 @@ SVCTHREAD *
 fha_assign(SVCTHREAD *this_thread, struct svc_req *req,
     struct fha_params *softc)
 {
-	SVCPOOL *pool;
 	SVCTHREAD *thread;
 	struct fha_info i;
 	struct fha_hash_entry *fhe;
@@ -439,7 +425,6 @@ fha_assign(SVCTHREAD *this_thread, struc
 	if (req->rq_vers != 2 && req->rq_vers != 3)
 		return (this_thread);
 
-	pool = req->rq_xprt->xp_pool;
 	fha_extract_info(req, &i, cb);
 
 	/*

Modified: head/sys/rpc/svc.c
==============================================================================
--- head/sys/rpc/svc.c	Fri Dec 20 16:50:52 2013	(r259658)
+++ head/sys/rpc/svc.c	Fri Dec 20 17:39:07 2013	(r259659)
@@ -293,12 +293,10 @@ xprt_unregister_locked(SVCXPRT *xprt)
 {
 	SVCPOOL *pool = xprt->xp_pool;
 
+	mtx_assert(&xprt->xp_mlock, MA_OWNED);
 	KASSERT(xprt->xp_registered == TRUE,
 	    ("xprt_unregister_locked: not registered"));
-	if (xprt->xp_active) {
-		TAILQ_REMOVE(&pool->sp_active, xprt, xp_alink);
-		xprt->xp_active = FALSE;
-	}
+	xprt_inactive_locked(xprt);
 	TAILQ_REMOVE(&pool->sp_xlist, xprt, xp_link);
 	xprt->xp_registered = FALSE;
 }
@@ -320,25 +318,25 @@ xprt_unregister(SVCXPRT *xprt)
 	SVC_RELEASE(xprt);
 }
 
-static void
+/*
+ * Attempt to assign a service thread to this transport.
+ */
+static int
 xprt_assignthread(SVCXPRT *xprt)
 {
 	SVCPOOL *pool = xprt->xp_pool;
 	SVCTHREAD *st;
 
-	/*
-	 * Attempt to assign a service thread to this
-	 * transport.
-	 */
-	LIST_FOREACH(st, &pool->sp_idlethreads, st_ilink) {
-		if (st->st_xprt == NULL && STAILQ_EMPTY(&st->st_reqs))
-			break;
-	}
+	mtx_assert(&xprt->xp_mlock, MA_OWNED);
+	st = LIST_FIRST(&pool->sp_idlethreads);
 	if (st) {
+		LIST_REMOVE(st, st_ilink);
+		st->st_idle = FALSE;
 		SVC_ACQUIRE(xprt);
 		xprt->xp_thread = st;
 		st->st_xprt = xprt;
 		cv_signal(&st->st_cond);
+		return (TRUE);
 	} else {
 		/*
 		 * See if we can create a new thread. The
@@ -354,6 +352,7 @@ xprt_assignthread(SVCXPRT *xprt)
 			pool->sp_state = SVCPOOL_THREADWANTED;
 		}
 	}
+	return (FALSE);
 }
 
 void
@@ -372,9 +371,12 @@ xprt_active(SVCXPRT *xprt)
 	}
 
 	if (!xprt->xp_active) {
-		TAILQ_INSERT_TAIL(&pool->sp_active, xprt, xp_alink);
 		xprt->xp_active = TRUE;
-		xprt_assignthread(xprt);
+		if (xprt->xp_thread == NULL) {
+			if (!xprt_assignthread(xprt))
+				TAILQ_INSERT_TAIL(&pool->sp_active, xprt,
+				    xp_alink);
+		}
 	}
 
 	mtx_unlock(&pool->sp_lock);
@@ -385,8 +387,10 @@ xprt_inactive_locked(SVCXPRT *xprt)
 {
 	SVCPOOL *pool = xprt->xp_pool;
 
+	mtx_assert(&xprt->xp_mlock, MA_OWNED);
 	if (xprt->xp_active) {
-		TAILQ_REMOVE(&pool->sp_active, xprt, xp_alink);
+		if (xprt->xp_thread == NULL)
+			TAILQ_REMOVE(&pool->sp_active, xprt, xp_alink);
 		xprt->xp_active = FALSE;
 	}
 }
@@ -948,10 +952,11 @@ svc_assign_waiting_sockets(SVCPOOL *pool
 {
 	SVCXPRT *xprt;
 
-	TAILQ_FOREACH(xprt, &pool->sp_active, xp_alink) {
-		if (!xprt->xp_thread) {
-			xprt_assignthread(xprt);
-		}
+	while ((xprt = TAILQ_FIRST(&pool->sp_active)) != NULL) {
+		if (xprt_assignthread(xprt))
+			TAILQ_REMOVE(&pool->sp_active, xprt, xp_alink);
+		else
+			break;
 	}
 }
 
@@ -1042,21 +1047,17 @@ svc_run_internal(SVCPOOL *pool, bool_t i
 			 * active transport which isn't being serviced
 			 * by a thread.
 			 */
-			if (svc_request_space_available(pool)) {
-				TAILQ_FOREACH(xprt, &pool->sp_active,
-				    xp_alink) {
-					if (!xprt->xp_thread) {
-						SVC_ACQUIRE(xprt);
-						xprt->xp_thread = st;
-						st->st_xprt = xprt;
-						break;
-					}
-				}
-			}
-			if (st->st_xprt)
+			if (svc_request_space_available(pool) &&
+			    (xprt = TAILQ_FIRST(&pool->sp_active)) != NULL) {
+				TAILQ_REMOVE(&pool->sp_active, xprt, xp_alink);
+				SVC_ACQUIRE(xprt);
+				xprt->xp_thread = st;
+				st->st_xprt = xprt;
 				continue;
+			}
 
 			LIST_INSERT_HEAD(&pool->sp_idlethreads, st, st_ilink);
+			st->st_idle = TRUE;
 			if (ismaster || (!ismaster &&
 			    pool->sp_threadcount > pool->sp_minthreads))
 				error = cv_timedwait_sig(&st->st_cond,
@@ -1064,7 +1065,10 @@ svc_run_internal(SVCPOOL *pool, bool_t i
 			else
 				error = cv_wait_sig(&st->st_cond,
 				    &pool->sp_lock);
-			LIST_REMOVE(st, st_ilink);
+			if (st->st_idle) {
+				LIST_REMOVE(st, st_ilink);
+				st->st_idle = FALSE;
+			}
 
 			/*
 			 * Reduce worker thread count when idle.
@@ -1132,11 +1136,12 @@ svc_run_internal(SVCPOOL *pool, bool_t i
 					 * execute the request
 					 * immediately.
 					 */
-					if (stpref != st) {
-						cv_signal(&stpref->st_cond);
-						continue;
-					} else {
+					if (stpref == st)
 						break;
+					if (stpref->st_idle) {
+						LIST_REMOVE(stpref, st_ilink);
+						stpref->st_idle = FALSE;
+						cv_signal(&stpref->st_cond);
 					}
 				}
 			} while (stat == XPRT_MOREREQS
@@ -1153,10 +1158,9 @@ svc_run_internal(SVCPOOL *pool, bool_t i
 			xprt->xp_thread = NULL;
 			st->st_xprt = NULL;
 			if (xprt->xp_active) {
-				xprt_assignthread(xprt);
-				TAILQ_REMOVE(&pool->sp_active, xprt, xp_alink);
-				TAILQ_INSERT_TAIL(&pool->sp_active, xprt,
-				    xp_alink);
+				if (!xprt_assignthread(xprt))
+					TAILQ_INSERT_TAIL(&pool->sp_active,
+					    xprt, xp_alink);
 			}
 			mtx_unlock(&pool->sp_lock);
 			SVC_RELEASE(xprt);

Modified: head/sys/rpc/svc.h
==============================================================================
--- head/sys/rpc/svc.h	Fri Dec 20 16:50:52 2013	(r259658)
+++ head/sys/rpc/svc.h	Fri Dec 20 17:39:07 2013	(r259659)
@@ -278,6 +278,7 @@ typedef struct __rpc_svcthread {
 	SVCXPRT			*st_xprt; /* transport we are processing */
 	struct svc_reqlist	st_reqs;  /* RPC requests to execute */
 	int			st_reqcount; /* number of queued reqs */
+	int			st_idle; /* thread is on idle list */
 	struct cv		st_cond; /* sleeping for work */
 	LIST_ENTRY(__rpc_svcthread) st_link; /* all threads list */
 	LIST_ENTRY(__rpc_svcthread) st_ilink; /* idle threads list */


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