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From: Stephen Hemminger <stephen@networkplumber.org>
To: dev@dpdk.org
Cc: Stephen Hemminger <stephen@networkplumber.org>,
	Reshma Pattan <reshma.pattan@intel.com>
Subject: [PATCH v5 7/9] latencystats: add metric for number of samples
Date: Mon, 22 Apr 2024 08:21:37 -0700	[thread overview]
Message-ID: <20240422152336.147553-8-stephen@networkplumber.org> (raw)
In-Reply-To: <20240422152336.147553-1-stephen@networkplumber.org>

Keeping track of the number of samples is useful when doing
debug and testing to make sure that samples are actually happening.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/latencystats/rte_latencystats.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/lib/latencystats/rte_latencystats.c b/lib/latencystats/rte_latencystats.c
index 8311adb411..e5a84fbd92 100644
--- a/lib/latencystats/rte_latencystats.c
+++ b/lib/latencystats/rte_latencystats.c
@@ -59,6 +59,7 @@ struct rte_latency_stats {
 	uint64_t avg_latency; /**< Average latency */
 	uint64_t max_latency; /**< Maximum latency */
 	uint64_t jitter; /** Latency variation */
+	uint64_t samples;    /** Number of latency samples */
 	rte_spinlock_t lock; /** Latency calculation lock */
 };
 
@@ -82,20 +83,26 @@ static const struct latency_stats_nameoff lat_stats_strings[] = {
 	{"avg_latency_ns", offsetof(struct rte_latency_stats, avg_latency), LATENCY_AVG_SCALE},
 	{"max_latency_ns", offsetof(struct rte_latency_stats, max_latency), 1},
 	{"jitter_ns", offsetof(struct rte_latency_stats, jitter), LATENCY_JITTER_SCALE},
+	{"samples", offsetof(struct rte_latency_stats, samples), 0},
 };
 
-#define NUM_LATENCY_STATS (sizeof(lat_stats_strings) / \
-				sizeof(lat_stats_strings[0]))
+#define NUM_LATENCY_STATS RTE_DIM(lat_stats_strings)
 
 static void
 latencystats_collect(uint64_t values[])
 {
-	unsigned int i;
+	unsigned int i, scale;
 	const uint64_t *stats;
 
 	for (i = 0; i < NUM_LATENCY_STATS; i++) {
 		stats = RTE_PTR_ADD(glob_stats, lat_stats_strings[i].offset);
-		values[i] = floor(*stats / (cycles_per_ns * lat_stats_strings[i].scale));
+		scale = lat_stats_strings[i].scale;
+
+		/* used to mark samples which are not a time interval */
+		if (scale == 0)
+			values[i] = *stats;
+		else
+			values[i] = floor(*stats / (cycles_per_ns * scale));
 	}
 }
 
@@ -173,7 +180,6 @@ calc_latency(uint16_t pid __rte_unused,
 	unsigned int i;
 	uint64_t now, latency;
 	static uint64_t prev_latency;
-	static bool first_sample = true;
 
 	now = rte_rdtsc();
 
@@ -184,9 +190,7 @@ calc_latency(uint16_t pid __rte_unused,
 
 		latency = now - *timestamp_dynfield(pkts[i]);
 
-		if (unlikely(first_sample)) {
-			first_sample = false;
-
+		if (glob_stats->samples++ == 0) {
 			glob_stats->min_latency = latency;
 			glob_stats->max_latency = latency;
 			glob_stats->avg_latency = latency * 4;
-- 
2.43.0


  parent reply	other threads:[~2024-04-22 15:24 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-08 19:50 [RFC] latencystats: performance overhaul Stephen Hemminger
2024-04-08 21:26 ` [PATCH v2] " Stephen Hemminger
2024-04-19 17:28 ` [PATCH v4 0/6] latencystats: cleanup Stephen Hemminger
2024-04-19 17:28   ` [PATCH v4 1/6] latencystats: replace use of VLA Stephen Hemminger
2024-04-19 17:28   ` [PATCH v4 2/6] latencystats: handle fractional cycles per ns Stephen Hemminger
2024-04-19 17:28   ` [PATCH v4 3/6] latencystats: do not use floating point Stephen Hemminger
2024-04-19 18:49     ` Morten Brørup
2024-04-19 22:45       ` Stephen Hemminger
2024-04-20  7:31         ` Morten Brørup
2024-04-19 17:28   ` [PATCH v4 4/6] latencystats: fix log messages Stephen Hemminger
2024-04-19 17:28   ` [PATCH v4 5/6] latencystats: update include files Stephen Hemminger
2024-04-19 17:28   ` [PATCH v4 6/6] latencystats: fix for pedantic warnings Stephen Hemminger
2024-04-22 15:21 ` [PATCH v5 0/9] latencystats: improve algorithms and tests Stephen Hemminger
2024-04-22 15:21   ` [PATCH v5 1/9] latencystats: replace use of VLA Stephen Hemminger
2024-04-22 15:21   ` [PATCH v5 2/9] latencystats: handle fractional cycles per ns Stephen Hemminger
2024-04-22 15:21   ` [PATCH v5 3/9] latencystats: do not use floating point Stephen Hemminger
2024-04-22 15:21   ` [PATCH v5 4/9] latencystats: fix log messages Stephen Hemminger
2024-04-22 15:21   ` [PATCH v5 5/9] latencystats: update include files Stephen Hemminger
2024-04-22 15:21   ` [PATCH v5 6/9] latencystats: enforce that unused callback function is NULL Stephen Hemminger
2024-04-22 15:21   ` Stephen Hemminger [this message]
2024-04-22 15:21   ` [PATCH v5 8/9] test: use initialization in latencystats test Stephen Hemminger
2024-04-22 15:21   ` [PATCH v5 9/9] test: add more latencystats tests Stephen Hemminger
2024-05-29 22:54 ` [PATCH v6 0/8] latencystats: improvements to algorithm and test Stephen Hemminger
2024-05-29 22:54   ` [PATCH v6 1/8] latencystats: replace use of VLA Stephen Hemminger
2024-05-29 22:54   ` [PATCH v6 2/8] latencystats: handle fractional cycles per ns Stephen Hemminger
2024-05-29 22:54   ` [PATCH v6 3/8] latencystats: do not use floating point Stephen Hemminger
2024-05-29 22:54   ` [PATCH v6 4/8] latencystats: fix log messages Stephen Hemminger
2024-05-29 22:54   ` [PATCH v6 5/8] latencystats: update include files Stephen Hemminger
2024-05-29 22:54   ` [PATCH v6 6/8] latencystats: enforce that unused callback function is NULL Stephen Hemminger
2024-05-29 22:54   ` [PATCH v6 7/8] latencystats: add metric for number of samples Stephen Hemminger
2024-05-29 22:54   ` [PATCH v6 8/8] test: update to latencystats tests Stephen Hemminger
2024-07-04 15:21   ` [PATCH v6 0/8] latencystats: improvements to algorithm and test David Marchand

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