From mboxrd@z Thu Jan 1 00:00:00 1970 From: Reshma Pattan Subject: [PATCH v3] latencystats: fix timestamp marking and latency calculation Date: Tue, 25 Sep 2018 15:51:26 +0100 Message-ID: <1537887086-19960-1-git-send-email-reshma.pattan@intel.com> References: <1537545703-9599-1-git-send-email-reshma.pattan@intel.com> Cc: stable@dpdk.org, Reshma Pattan To: longtb5@viettel.com.vn, konstantin.ananyev@intel.com, dev@dpdk.org Return-path: In-Reply-To: <1537545703-9599-1-git-send-email-reshma.pattan@intel.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Latency calculation logic is not correct for the case where packets gets dropped before TX. As for the dropped packets, the timestamp is not cleared, and such packets still gets counted for latency calculation in next runs, that will result in inaccurate latency measurement. So fix this issue as below, Before setting timestamp in mbuf, check mbuf don't have any prior valid time stamp flag set and after marking the timestamp, set mbuf flags to indicate timestamp is valid. Before calculating timestamp check mbuf flags are set to indicate timestamp is valid. With the above logic it is guaranteed that correct timestamps have been used. Fixes: 5cd3cac9ed ("latency: added new library for latency stats") CC: stable@dpdk.org Reported-by: Bao-Long Tran Signed-off-by: Reshma Pattan Tested-by: Bao-Long Tran Acked-by: Konstantin Ananyev --- v3: style related fix v2: remove check for mbuf->timestamp --- lib/librte_latencystats/rte_latencystats.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/lib/librte_latencystats/rte_latencystats.c b/lib/librte_latencystats/rte_latencystats.c index 1fdec68e3..5715549e4 100644 --- a/lib/librte_latencystats/rte_latencystats.c +++ b/lib/librte_latencystats/rte_latencystats.c @@ -125,8 +125,11 @@ add_time_stamps(uint16_t pid __rte_unused, for (i = 0; i < nb_pkts; i++) { diff_tsc = now - prev_tsc; timer_tsc += diff_tsc; - if (timer_tsc >= samp_intvl) { + + if ((pkts[i]->ol_flags & PKT_RX_TIMESTAMP) == 0 + && (timer_tsc >= samp_intvl)) { pkts[i]->timestamp = now; + pkts[i]->ol_flags |= PKT_RX_TIMESTAMP; timer_tsc = 0; } prev_tsc = now; @@ -156,7 +159,7 @@ calc_latency(uint16_t pid __rte_unused, now = rte_rdtsc(); for (i = 0; i < nb_pkts; i++) { - if (pkts[i]->timestamp) + if (pkts[i]->ol_flags & PKT_RX_TIMESTAMP) latency[cnt++] = now - pkts[i]->timestamp; } -- 2.17.1