From: Stephen Hemminger <shemminger@vyatta.com>
Date: Thu, 30 May 2013 17:12:36 +0000 (+0000)
Subject: timer: optimize for empty case
X-Git-Tag: spdx-start~11248
X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=3778059a51fcbc6b989ca7503a3ff89f6945ddd2;hp=6286101324294f7922f0268007252d1f008c49e4;p=dpdk.git

timer: optimize for empty case

In many application there are no timers queued, and the call to
rte_timer_managecan be optimized in that case avoid reading HPET and
lock overhead.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Reviewed-by: Vincent Jardin <vincent.jardin@6wind.com>
---

diff --git a/lib/librte_timer/rte_timer.c b/lib/librte_timer/rte_timer.c
index 095547a5b6..c9b253a820 100644
--- a/lib/librte_timer/rte_timer.c
+++ b/lib/librte_timer/rte_timer.c
@@ -403,9 +403,14 @@ void rte_timer_manage(void)
 	union rte_timer_status status;
 	struct rte_timer *tim, *tim2;
 	unsigned lcore_id = rte_lcore_id();
-	uint64_t cur_time = rte_get_hpet_cycles();
+	uint64_t cur_time;
 	int ret;
 
+	/* optimize for the case where per-cpu list is empty */
+	if (LIST_EMPTY(&priv_timer[lcore_id].pending))
+		return;
+
+	cur_time = rte_get_hpet_cycles();
 	__TIMER_STAT_ADD(manage, 1);
 
 	/* browse ordered list, add expired timers in 'expired' list */