[dpdk-dev] [RFC PATCH] timer: inform periodic timers of multiple expiries

Bruce Richardson bruce.richardson at intel.com
Fri Apr 28 15:25:38 CEST 2017


if timer_manage is called much less frequently than the period of a
periodic timer, then timer expiries will be missed. For example, if a timer
has a period of 300us, but timer_manage is called every 1ms, then there
will only be one timer callback called every 1ms instead of 3 within that
time.

While we can fix this by having each function called multiple times within
timer-manage, this will lead to out-of-order timeouts, and will be slower
with all the function call overheads - especially in the case of a timeout
doing something trivial like incrementing a counter. Therefore, we instead
modify the callback functions to take a counter value of the number of
expiries that have passed since the last time it was called.

Signed-off-by: Bruce Richardson <bruce.richardson at intel.com>
---
 examples/l2fwd-jobstats/main.c                     |  7 +++++--
 examples/l2fwd-keepalive/main.c                    |  8 ++++----
 examples/l3fwd-power/main.c                        |  5 +++--
 examples/performance-thread/common/lthread_sched.c |  4 +++-
 examples/performance-thread/common/lthread_sched.h |  2 +-
 examples/timer/main.c                              | 10 ++++++----
 lib/librte_timer/rte_timer.c                       |  9 ++++++++-
 lib/librte_timer/rte_timer.h                       |  2 +-
 test/test/test_timer.c                             | 14 +++++++++-----
 test/test/test_timer_perf.c                        |  4 +++-
 test/test/test_timer_racecond.c                    |  3 ++-
 11 files changed, 45 insertions(+), 23 deletions(-)

diff --git a/examples/l2fwd-jobstats/main.c b/examples/l2fwd-jobstats/main.c
index e6e6c22..b264344 100644
--- a/examples/l2fwd-jobstats/main.c
+++ b/examples/l2fwd-jobstats/main.c
@@ -410,7 +410,8 @@ l2fwd_job_update_cb(struct rte_jobstats *job, int64_t result)
 }
 
 static void
-l2fwd_fwd_job(__rte_unused struct rte_timer *timer, void *arg)
+l2fwd_fwd_job(__rte_unused struct rte_timer *timer,
+		__rte_unused unsigned int count, void *arg)
 {
 	struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
 	struct rte_mbuf *m;
@@ -460,7 +461,9 @@ l2fwd_fwd_job(__rte_unused struct rte_timer *timer, void *arg)
 }
 
 static void
-l2fwd_flush_job(__rte_unused struct rte_timer *timer, __rte_unused void *arg)
+l2fwd_flush_job(__rte_unused struct rte_timer *timer,
+		__rte_unused unsigned int count,
+		__rte_unused void *arg)
 {
 	uint64_t now;
 	unsigned lcore_id;
diff --git a/examples/l2fwd-keepalive/main.c b/examples/l2fwd-keepalive/main.c
index 4623d2a..26eba12 100644
--- a/examples/l2fwd-keepalive/main.c
+++ b/examples/l2fwd-keepalive/main.c
@@ -144,8 +144,9 @@ struct rte_keepalive *rte_global_keepalive_info;
 
 /* Print out statistics on packets dropped */
 static void
-print_stats(__attribute__((unused)) struct rte_timer *ptr_timer,
-	__attribute__((unused)) void *ptr_data)
+print_stats(__rte_unused struct rte_timer *ptr_timer,
+		__rte_unused unsigned int count,
+		__rte_unused void *ptr_data)
 {
 	uint64_t total_packets_dropped, total_packets_tx, total_packets_rx;
 	unsigned portid;
@@ -748,8 +749,7 @@ main(int argc, char **argv)
 				(check_period * rte_get_timer_hz()) / 1000,
 				PERIODICAL,
 				rte_lcore_id(),
-				(void(*)(struct rte_timer*, void*))
-				&rte_keepalive_dispatch_pings,
+				(void *)&rte_keepalive_dispatch_pings,
 				rte_global_keepalive_info
 				) != 0 )
 			rte_exit(EXIT_FAILURE, "Keepalive setup failure.\n");
diff --git a/examples/l3fwd-power/main.c b/examples/l3fwd-power/main.c
index ec40a17..318aefd 100644
--- a/examples/l3fwd-power/main.c
+++ b/examples/l3fwd-power/main.c
@@ -410,8 +410,9 @@ signal_exit_now(int sigtype)
 
 /*  Freqency scale down timer callback */
 static void
-power_timer_cb(__attribute__((unused)) struct rte_timer *tim,
-			  __attribute__((unused)) void *arg)
+power_timer_cb(__rte_unused struct rte_timer *tim,
+		__rte_unused unsigned int count,
+		__rte_unused void *arg)
 {
 	uint64_t hz;
 	float sleep_time_ratio;
diff --git a/examples/performance-thread/common/lthread_sched.c b/examples/performance-thread/common/lthread_sched.c
index c64c21f..c4c7d3b 100644
--- a/examples/performance-thread/common/lthread_sched.c
+++ b/examples/performance-thread/common/lthread_sched.c
@@ -437,7 +437,9 @@ static inline void _lthread_resume(struct lthread *lt)
  * Handle sleep timer expiry
 */
 void
-_sched_timer_cb(struct rte_timer *tim, void *arg)
+_sched_timer_cb(struct rte_timer *tim,
+		unsigned int count __rte_unused,
+		void *arg)
 {
 	struct lthread *lt = (struct lthread *) arg;
 	uint64_t state = lt->state;
diff --git a/examples/performance-thread/common/lthread_sched.h b/examples/performance-thread/common/lthread_sched.h
index 7cddda9..f2af8b3 100644
--- a/examples/performance-thread/common/lthread_sched.h
+++ b/examples/performance-thread/common/lthread_sched.h
@@ -149,7 +149,7 @@ _reschedule(void)
 }
 
 extern struct lthread_sched *schedcore[];
-void _sched_timer_cb(struct rte_timer *tim, void *arg);
+void _sched_timer_cb(struct rte_timer *tim, unsigned int count, void *arg);
 void _sched_shutdown(__rte_unused void *arg);
 
 #ifdef __cplusplus
diff --git a/examples/timer/main.c b/examples/timer/main.c
index 37ad559..92a6a1f 100644
--- a/examples/timer/main.c
+++ b/examples/timer/main.c
@@ -55,8 +55,9 @@ static struct rte_timer timer1;
 
 /* timer0 callback */
 static void
-timer0_cb(__attribute__((unused)) struct rte_timer *tim,
-	  __attribute__((unused)) void *arg)
+timer0_cb(__rte_unused struct rte_timer *tim,
+	  __rte_unused unsigned int count,
+	  __rte_unused void *arg)
 {
 	static unsigned counter = 0;
 	unsigned lcore_id = rte_lcore_id();
@@ -71,8 +72,9 @@ timer0_cb(__attribute__((unused)) struct rte_timer *tim,
 
 /* timer1 callback */
 static void
-timer1_cb(__attribute__((unused)) struct rte_timer *tim,
-	  __attribute__((unused)) void *arg)
+timer1_cb(__rte_unused struct rte_timer *tim,
+	  __rte_unused unsigned int count,
+	  __rte_unused void *arg)
 {
 	unsigned lcore_id = rte_lcore_id();
 	uint64_t hz;
diff --git a/lib/librte_timer/rte_timer.c b/lib/librte_timer/rte_timer.c
index 18782fa..d1e2c12 100644
--- a/lib/librte_timer/rte_timer.c
+++ b/lib/librte_timer/rte_timer.c
@@ -590,7 +590,14 @@ void rte_timer_manage(void)
 		priv_timer[lcore_id].running_tim = tim;
 
 		/* execute callback function with list unlocked */
-		tim->f(tim, tim->arg);
+		if (tim->period == 0)
+			tim->f(tim, 1, tim->arg);
+		else {
+			/* for periodic check how many expiries we have */
+			uint64_t over_time = cur_time - tim->expire;
+			unsigned int extra_expiries = over_time / tim->period;
+			tim->f(tim, 1 + extra_expiries, tim->arg);
+		}
 
 		__TIMER_STAT_ADD(pending, -1);
 		/* the timer was stopped or reloaded by the callback
diff --git a/lib/librte_timer/rte_timer.h b/lib/librte_timer/rte_timer.h
index a276a73..bc434ec 100644
--- a/lib/librte_timer/rte_timer.h
+++ b/lib/librte_timer/rte_timer.h
@@ -117,7 +117,7 @@ struct rte_timer;
 /**
  * Callback function type for timer expiry.
  */
-typedef void (*rte_timer_cb_t)(struct rte_timer *, void *);
+typedef void (*rte_timer_cb_t)(struct rte_timer *, unsigned int count, void *);
 
 #define MAX_SKIPLIST_DEPTH 10
 
diff --git a/test/test/test_timer.c b/test/test/test_timer.c
index 2f6525a..0b86d3c 100644
--- a/test/test/test_timer.c
+++ b/test/test/test_timer.c
@@ -153,7 +153,8 @@ struct mytimerinfo {
 
 static struct mytimerinfo mytiminfo[NB_TIMER];
 
-static void timer_basic_cb(struct rte_timer *tim, void *arg);
+static void
+timer_basic_cb(struct rte_timer *tim, unsigned int count, void *arg);
 
 static void
 mytimer_reset(struct mytimerinfo *timinfo, uint64_t ticks,
@@ -167,6 +168,7 @@ mytimer_reset(struct mytimerinfo *timinfo, uint64_t ticks,
 /* timer callback for stress tests */
 static void
 timer_stress_cb(__attribute__((unused)) struct rte_timer *tim,
+		__attribute__((unused)) unsigned int count,
 		__attribute__((unused)) void *arg)
 {
 	long r;
@@ -293,9 +295,11 @@ static volatile int cb_count = 0;
 /* callback for second stress test. will only be called
  * on master lcore */
 static void
-timer_stress2_cb(struct rte_timer *tim __rte_unused, void *arg __rte_unused)
+timer_stress2_cb(struct rte_timer *tim __rte_unused,
+		unsigned int count,
+		void *arg __rte_unused)
 {
-	cb_count++;
+	cb_count += count;
 }
 
 #define NB_STRESS2_TIMERS 8192
@@ -430,7 +434,7 @@ timer_stress2_main_loop(__attribute__((unused)) void *arg)
 
 /* timer callback for basic tests */
 static void
-timer_basic_cb(struct rte_timer *tim, void *arg)
+timer_basic_cb(struct rte_timer *tim, unsigned int count, void *arg)
 {
 	struct mytimerinfo *timinfo = arg;
 	uint64_t hz = rte_get_timer_hz();
@@ -440,7 +444,7 @@ timer_basic_cb(struct rte_timer *tim, void *arg)
 	if (rte_timer_pending(tim))
 		return;
 
-	timinfo->count ++;
+	timinfo->count += count;
 
 	RTE_LOG(INFO, TESTTIMER,
 		"%"PRIu64": callback id=%u count=%u on core %u\n",
diff --git a/test/test/test_timer_perf.c b/test/test/test_timer_perf.c
index fa77efb..5b3867d 100644
--- a/test/test/test_timer_perf.c
+++ b/test/test/test_timer_perf.c
@@ -48,7 +48,9 @@
 int outstanding_count = 0;
 
 static void
-timer_cb(struct rte_timer *t __rte_unused, void *param __rte_unused)
+timer_cb(struct rte_timer *t __rte_unused,
+		unsigned int count __rte_unused,
+		void *param __rte_unused)
 {
 	outstanding_count--;
 }
diff --git a/test/test/test_timer_racecond.c b/test/test/test_timer_racecond.c
index 7824ec4..b1c5c86 100644
--- a/test/test/test_timer_racecond.c
+++ b/test/test/test_timer_racecond.c
@@ -65,7 +65,8 @@ static volatile unsigned stop_slaves;
 static int reload_timer(struct rte_timer *tim);
 
 static void
-timer_cb(struct rte_timer *tim, void *arg __rte_unused)
+timer_cb(struct rte_timer *tim, unsigned int count __rte_unused,
+		void *arg __rte_unused)
 {
 	/* Simulate slow callback function, 100 us. */
 	rte_delay_us(100);
-- 
2.9.3



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