diff options
| author | Bruce A. Mah <bmah@es.net> | 2017-05-05 08:59:13 -0700 |
|---|---|---|
| committer | Bruce A. Mah <bmah@es.net> | 2017-05-05 08:59:13 -0700 |
| commit | 67653543ad750acbd816d7473a56f721bb811383 (patch) | |
| tree | ce4b69fbfbce636ea15eb07d80fbd48b87c11d26 /src | |
| parent | 103d4318e85783b99d6984c091ea878fc0d844b2 (diff) | |
| download | iperf3-67653543ad750acbd816d7473a56f721bb811383.tar.gz | |
Improve / fix comments regarding UDP jitter calculation.
Internal documentation fix only, no functional change.
Diffstat (limited to 'src')
| -rw-r--r-- | src/iperf_udp.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/src/iperf_udp.c b/src/iperf_udp.c index b32f574..85ef4d4 100644 --- a/src/iperf_udp.c +++ b/src/iperf_udp.c @@ -108,7 +108,17 @@ iperf_udp_recv(struct iperf_stream *sp) iperf_err(sp->test, "OUT OF ORDER - incoming packet = %zu and received packet = %d AND SP = %d", pcount, sp->packet_count, sp->socket); } - /* jitter measurement */ + /* + * jitter measurement + * + * This computation is based on RFC 1889 (specifically + * sections 6.3.1 and A.8). + * + * Note that synchronized clocks are not required since + * the source packet delta times are known. Also this + * computation does not require knowing the round-trip + * time. + */ gettimeofday(&arrival_time, NULL); transit = timeval_diff(&sent_time, &arrival_time); @@ -116,8 +126,6 @@ iperf_udp_recv(struct iperf_stream *sp) if (d < 0) d = -d; sp->prev_transit = transit; - // XXX: This is NOT the way to calculate jitter - // J = |(R1 - S1) - (R0 - S0)| [/ number of packets, for average] sp->jitter += (d - sp->jitter) / 16.0; if (sp->test->debug) { |