From: Stephen Hemminger <stephen@networkplumber.org>
To: dev@dpdk.org
Cc: Stephen Hemminger <stephen@networkplumber.org>,
Reshma Pattan <reshma.pattan@intel.com>
Subject: [PATCH v3 1/5] latencystats: replace use of VLA
Date: Wed, 17 Apr 2024 10:07:23 -0700 [thread overview]
Message-ID: <20240417170908.76701-2-stephen@networkplumber.org> (raw)
In-Reply-To: <20240417170908.76701-1-stephen@networkplumber.org>
The temporary array latencystats is not needed if the algorithm
is converted into one pass.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
lib/latencystats/rte_latencystats.c | 31 +++++++++++++++--------------
1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/lib/latencystats/rte_latencystats.c b/lib/latencystats/rte_latencystats.c
index 4ea9b0d75b..9b345bfb33 100644
--- a/lib/latencystats/rte_latencystats.c
+++ b/lib/latencystats/rte_latencystats.c
@@ -157,9 +157,9 @@ calc_latency(uint16_t pid __rte_unused,
uint16_t nb_pkts,
void *_ __rte_unused)
{
- unsigned int i, cnt = 0;
+ unsigned int i;
uint64_t now;
- float latency[nb_pkts];
+ float latency;
static float prev_latency;
/*
* Alpha represents degree of weighting decrease in EWMA,
@@ -169,13 +169,14 @@ calc_latency(uint16_t pid __rte_unused,
const float alpha = 0.2;
now = rte_rdtsc();
- for (i = 0; i < nb_pkts; i++) {
- if (pkts[i]->ol_flags & timestamp_dynflag)
- latency[cnt++] = now - *timestamp_dynfield(pkts[i]);
- }
rte_spinlock_lock(&glob_stats->lock);
- for (i = 0; i < cnt; i++) {
+ for (i = 0; i < nb_pkts; i++) {
+ if (!(pkts[i]->ol_flags & timestamp_dynflag))
+ continue;
+
+ latency = now - *timestamp_dynfield(pkts[i]);
+
/*
* The jitter is calculated as statistical mean of interpacket
* delay variation. The "jitter estimate" is computed by taking
@@ -187,22 +188,22 @@ calc_latency(uint16_t pid __rte_unused,
* Reference: Calculated as per RFC 5481, sec 4.1,
* RFC 3393 sec 4.5, RFC 1889 sec.
*/
- glob_stats->jitter += (fabsf(prev_latency - latency[i])
+ glob_stats->jitter += (fabsf(prev_latency - latency)
- glob_stats->jitter)/16;
if (glob_stats->min_latency == 0)
- glob_stats->min_latency = latency[i];
- else if (latency[i] < glob_stats->min_latency)
- glob_stats->min_latency = latency[i];
- else if (latency[i] > glob_stats->max_latency)
- glob_stats->max_latency = latency[i];
+ glob_stats->min_latency = latency;
+ else if (latency < glob_stats->min_latency)
+ glob_stats->min_latency = latency;
+ else if (latency > glob_stats->max_latency)
+ glob_stats->max_latency = latency;
/*
* The average latency is measured using exponential moving
* average, i.e. using EWMA
* https://en.wikipedia.org/wiki/Moving_average
*/
glob_stats->avg_latency +=
- alpha * (latency[i] - glob_stats->avg_latency);
- prev_latency = latency[i];
+ alpha * (latency - glob_stats->avg_latency);
+ prev_latency = latency;
}
rte_spinlock_unlock(&glob_stats->lock);
--
2.43.0
next prev parent reply other threads:[~2024-04-17 17:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <0240408195036.182545-1-stephen@networkplumber.org>
2024-04-17 17:07 ` [PATCH v3 0/5] latencystats: cleanups Stephen Hemminger
2024-04-17 17:07 ` Stephen Hemminger [this message]
2024-04-17 18:03 ` [PATCH v3 1/5] latencystats: replace use of VLA Morten Brørup
2024-04-17 18:13 ` Stephen Hemminger
2024-04-18 0:00 ` Tyler Retzlaff
2024-04-17 17:07 ` [PATCH v3 2/5] latencystats: handle fractional cycles per ns Stephen Hemminger
2024-04-18 0:03 ` Tyler Retzlaff
2024-04-17 17:07 ` [PATCH v3 3/5] latencystats: do not use floating point Stephen Hemminger
2024-04-18 0:10 ` Tyler Retzlaff
2024-04-17 17:07 ` [PATCH v3 4/5] latencystats: fix log messages Stephen Hemminger
2024-04-18 0:13 ` Tyler Retzlaff
2024-04-17 17:07 ` [PATCH v3 5/5] latencystats: include file cleanup Stephen Hemminger
2024-04-17 17:30 ` Bruce Richardson
2024-04-17 18:13 ` Stephen Hemminger
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240417170908.76701-2-stephen@networkplumber.org \
--to=stephen@networkplumber.org \
--cc=dev@dpdk.org \
--cc=reshma.pattan@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).