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From: longtb5@viettel.com.vn
To: reshma.pattan@intel.com
Cc: dev@dpdk.org, Bao-Long Tran <longtb5@viettel.com.vn>, stable@dpdk.org
Subject: [dpdk-dev] [PATCH v2] latency: clear mbuf timestamp after latency calculation
Date: Thu, 20 Sep 2018 18:16:33 +0700 (ICT)	[thread overview]
Message-ID: <1537442655-99749-1-git-send-email-longtb5@viettel.com.vn> (raw)
In-Reply-To: <1537345834-70456-1-git-send-email-longtb5@viettel.com.vn>

The timestamp of a mbuf should be cleared after that mbuf was used for
latency calculation, otherwise future packets which reuse the same mbuf
would inherit that previous timestamp. The latencystats library looks
for mbuf with non-zero timestamp, thus incorrectly inherited value would
result in incorrect latency measurement.

Fixes: 5cd3cac9ed ("latency: added new library for latency stats").
Cc: stable@dpdk.org

Signed-off-by: Bao-Long Tran <longtb5@viettel.com.vn>
Acked-by: Reshma Pattan <reshma.pattan@intel.com>
---
 lib/librte_latencystats/rte_latencystats.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/librte_latencystats/rte_latencystats.c b/lib/librte_latencystats/rte_latencystats.c
index 1fdec68..2d5384e 100644
--- a/lib/librte_latencystats/rte_latencystats.c
+++ b/lib/librte_latencystats/rte_latencystats.c
@@ -156,8 +156,10 @@ calc_latency(uint16_t pid __rte_unused,
 
 	now = rte_rdtsc();
 	for (i = 0; i < nb_pkts; i++) {
-		if (pkts[i]->timestamp)
+		if (pkts[i]->timestamp) {
 			latency[cnt++] = now - pkts[i]->timestamp;
+			pkts[i]->timestamp = 0;
+		}
 	}
 
 	for (i = 0; i < cnt; i++) {
-- 
2.7.4

  parent reply	other threads:[~2018-09-20 11:16 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-19  8:17 [dpdk-dev] Incorrect latencystats implementation longtb5
2018-09-19  8:22 ` [dpdk-dev] [PATCH] latency: clear mbuf timestamp after latency calculation longtb5
2018-09-20 10:25   ` Pattan, Reshma
2018-09-20 12:16     ` longtb5
2018-09-20 11:16   ` longtb5 [this message]
2018-09-20 13:08 ` [dpdk-dev] Incorrect latencystats implementation Pattan, Reshma
2018-09-21  1:58   ` longtb5
2018-09-21 11:15     ` Pattan, Reshma
2018-09-21 12:14       ` Ananyev, Konstantin
2018-09-21 14:58         ` Pattan, Reshma

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