autofs-5.0.5 - remove state machine timed wait

From: Ian Kent <raven@themaw.net>

We are seeing a problem using timed waits when running under KVM.

Using timed condition waits in the state machine (and in some other

places) has been used because of observed task throughput problems

in the past. Also, we've seen condition waits not reacting to signals

occassionaly.

But now we are seeing problems with the setup of the wait time within

KVM VMs causing the condition wait to go into a tight loop using

excessive CPU.

Changing the state queue handler to not use timed waits appears to

not have the previously observed throughput problems, hopefully we

won't see lost signals either.

---

 CHANGELOG      |    1 +

 daemon/state.c |   30 +++++++-----------------------

 2 files changed, 8 insertions(+), 23 deletions(-)

--- autofs-5.0.5.orig/CHANGELOG

+++ autofs-5.0.5/CHANGELOG

@@ -42,6 +42,7 @@

 - fix mapent becomes negative during lookup.

 - check each dc server individually.

 - fix negative cache included map lookup.

+- remove state machine timed wait.

 03/09/2009 autofs-5.0.5

 -----------------------

--- autofs-5.0.5.orig/daemon/state.c

+++ autofs-5.0.5/daemon/state.c

@@ -197,11 +197,11 @@ void expire_cleanup(void *arg)

 		}

 	}

+	st_set_done(ap);

+

 	if (next != ST_INVAL)

 		__st_add_task(ap, next);

-	st_set_done(ap);

-

 	st_mutex_unlock();

 	return;

@@ -332,11 +332,10 @@ static void do_readmap_cleanup(void *arg

 	st_mutex_lock();

 	ap->readmap_thread = 0;

-	st_ready(ap);

 	st_set_done(ap);

-

 	if (!ap->submount)

 		alarm_add(ap, ap->exp_runfreq);

+	st_ready(ap);

 	st_mutex_unlock();

@@ -1060,8 +1059,6 @@ static void *st_queue_handler(void *arg)

 {

 	struct list_head *head;

 	struct list_head *p;

-	struct timespec wait;

-	struct timeval now;

 	int status, ret;

 	st_mutex_lock();

@@ -1072,17 +1069,11 @@ static void *st_queue_handler(void *arg)

 		 * entry is added.

 		 */

 		head = &state_queue;

-		gettimeofday(&now, NULL);

-		wait.tv_sec = now.tv_sec + 1;

-		wait.tv_nsec = now.tv_usec * 1000;

 		while (list_empty(head)) {

-			status = pthread_cond_timedwait(&cond, &mutex, &wait);

-			if (status) {

-				if (status == ETIMEDOUT)

-					break;

+			status = pthread_cond_wait(&cond, &mutex);

+			if (status)

 				fatal(status);

-			}

 		}

 		p = head->next;

@@ -1108,18 +1099,11 @@ static void *st_queue_handler(void *arg)

 		}

 		while (1) {

-			gettimeofday(&now, NULL);

-			wait.tv_sec = now.tv_sec + 1;

-			wait.tv_nsec = now.tv_usec * 1000;

-

 			signaled = 0;

 			while (!signaled) {

-				status = pthread_cond_timedwait(&cond, &mutex, &wait);

-				if (status) {

-					if (status == ETIMEDOUT)

-						break;

+				status = pthread_cond_wait(&cond, &mutex);

+				if (status)

 					fatal(status);

-				}

 			}

 			head = &state_queue;