staging/lustre: Only wake up ldlm_poold as frequently as the check interval

We used to wake up ldlm poold every second, but that's overkill,
we should just see how much time is left until next closest recalc
interval hits and sleep this much.
This will make "per-second" client grant statistic not actually
per-second, but I don't think we need any precision in that code

Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2924
Lustre-change: http://review.whamcloud.com/5793Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-by: Vitaly Fertman <vitaly_fertman@xyratex.com>
Reviewed-by: Hiroya Nozaki <nozaki.hiroya@jp.fujitsu.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/include/lustre_dlm.h

@@ -1643,7 +1643,7 @@ void unlock_res_and_lock(struct ldlm_lock *lock);
  * There are not used outside of ldlm.
  * @{
  */
-void ldlm_pools_recalc(ldlm_side_t client);
+int ldlm_pools_recalc(ldlm_side_t client);
 int ldlm_pools_init(void);
 void ldlm_pools_fini(void);
 

drivers/staging/lustre/lustre/ldlm/ldlm_pool.c

@@ -578,7 +578,6 @@ int ldlm_pool_recalc(struct ldlm_pool *pl)
 		goto recalc;
 
 	spin_lock(&pl->pl_lock);
-	recalc_interval_sec = cfs_time_current_sec() - pl->pl_recalc_time;
 	if (recalc_interval_sec > 0) {
 		/*
 		 * Update pool statistics every 1s.
@@ -598,12 +597,12 @@ int ldlm_pool_recalc(struct ldlm_pool *pl)
 		count = pl->pl_ops->po_recalc(pl);
 		lprocfs_counter_add(pl->pl_stats, LDLM_POOL_RECALC_STAT,
 				    count);
-		return count;
 	}
+	recalc_interval_sec = pl->pl_recalc_time - cfs_time_current_sec() +
+			      pl->pl_recalc_period;
 
-	return 0;
+	return recalc_interval_sec;
 }
-EXPORT_SYMBOL(ldlm_pool_recalc);
 
 /**
  * Pool shrink wrapper. Will call either client or server pool recalc callback
@@ -1144,12 +1143,13 @@ static int ldlm_pools_cli_shrink(SHRINKER_ARGS(sc, nr_to_scan, gfp_mask))
 				 shrink_param(sc, gfp_mask));
 }
 
-void ldlm_pools_recalc(ldlm_side_t client)
+int ldlm_pools_recalc(ldlm_side_t client)
 {
 	__u32 nr_l = 0, nr_p = 0, l;
 	struct ldlm_namespace *ns;
 	struct ldlm_namespace *ns_old = NULL;
 	int nr, equal = 0;
+	int time = 50; /* seconds of sleep if no active namespaces */
 
 	/*
 	 * No need to setup pool limit for client pools.
@@ -1285,16 +1285,22 @@ void ldlm_pools_recalc(ldlm_side_t client)
 		 * After setup is done - recalc the pool.
 		 */
 		if (!skip) {
-			ldlm_pool_recalc(&ns->ns_pool);
+			int ttime = ldlm_pool_recalc(&ns->ns_pool);
+
+			if (ttime < time)
+				time = ttime;
+
 			ldlm_namespace_put(ns);
 		}
 	}
+	return time;
 }
 EXPORT_SYMBOL(ldlm_pools_recalc);
 
 static int ldlm_pools_thread_main(void *arg)
 {
 	struct ptlrpc_thread *thread = (struct ptlrpc_thread *)arg;
+	int s_time, c_time;
 	ENTRY;
 
 	thread_set_flags(thread, SVC_RUNNING);
@@ -1309,14 +1315,14 @@ static int ldlm_pools_thread_main(void *arg)
 		/*
 		 * Recal all pools on this tick.
 		 */
-		ldlm_pools_recalc(LDLM_NAMESPACE_SERVER);
-		ldlm_pools_recalc(LDLM_NAMESPACE_CLIENT);
+		s_time = ldlm_pools_recalc(LDLM_NAMESPACE_SERVER);
+		c_time = ldlm_pools_recalc(LDLM_NAMESPACE_CLIENT);
 
 		/*
 		 * Wait until the next check time, or until we're
 		 * stopped.
 		 */
-		lwi = LWI_TIMEOUT(cfs_time_seconds(LDLM_POOLS_THREAD_PERIOD),
+		lwi = LWI_TIMEOUT(cfs_time_seconds(min(s_time, c_time)),
 				  NULL, NULL);
 		l_wait_event(thread->t_ctl_waitq,
 			     thread_is_stopping(thread) ||