Patch submission to fix ping interval.

[greearb]

Patch submission to fix ping interval.

[pevik]

Thanks for working on this. no answer yet for first reply would need to be fixed.

$ ./builddir/ping/ping -OD ::1
PING ::1 (::1) 56 data bytes
[1708670330.871771] no answer yet for icmp_seq=1
[1708670330.871817] 64 bytes from ::1: icmp_seq=1 ttl=64 time=0.041 ms
[1708670330.871832] 64 bytes from ::1: icmp_seq=2 ttl=64 time=0.013 ms
[1708670331.889429] 64 bytes from ::1: icmp_seq=3 ttl=64 time=0.058 ms
[1708670332.873644] 64 bytes from ::1: icmp_seq=4 ttl=64 time=0.068 ms

Have you tried a different interval than just the default 1s? It's slightly increasing.

$ ./builddir/ping/ping 8.8.8.8 -OD -i2
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
[1708670068.819166] no answer yet for icmp_seq=1
[1708670068.831540] 64 bytes from 8.8.8.8: icmp_seq=1 ttl=116 time=12.3 ms
[1708670068.832339] 64 bytes from 8.8.8.8: icmp_seq=2 ttl=116 time=13.1 ms
[1708670070.837011] 64 bytes from 8.8.8.8: icmp_seq=3 ttl=116 time=15.4 ms
[1708670072.838528] 64 bytes from 8.8.8.8: icmp_seq=4 ttl=116 time=16.3 ms
[1708670074.835015] 64 bytes from 8.8.8.8: icmp_seq=5 ttl=116 time=11.2 ms
...
[1708670174.842987] 64 bytes from 8.8.8.8: icmp_seq=55 ttl=116 time=11.1 ms
[1708670176.846084] 64 bytes from 8.8.8.8: icmp_seq=56 ttl=116 time=13.9 ms
[1708670178.843404] 64 bytes from 8.8.8.8: icmp_seq=57 ttl=116 time=11.9 ms
[1708670180.844339] 64 bytes from 8.8.8.8: icmp_seq=58 ttl=116 time=10.7 ms

nit (early return adds readability):

+++ ping/ping.h
@@ -311,18 +311,19 @@ static inline void tvsub(struct timeval *out, struct timeval *in)
 
 static inline void tsincr(struct timespec *out, int msec)
 {
-       if (msec) {
-               long incr_msecs = msec % 1000;
-               long incr_secs = msec / 1000;
-               long incr_nsecs = incr_msecs * 1000000;
-
-               if (out->tv_nsec + incr_nsecs > 1000000000) {
-                       incr_secs++;
-                       incr_nsecs -= 1000000000;
-               }
-               out->tv_sec += incr_secs;
-               out->tv_nsec += incr_nsecs;
+       if (!msec)
+               return;
+
+       long incr_msecs = msec % 1000;
+       long incr_secs = msec / 1000;
+       long incr_nsecs = incr_msecs * 1000000;
+
+       if (out->tv_nsec + incr_nsecs > 1000000000) {
+               incr_secs++;
+               incr_nsecs -= 1000000000;
        }
+       out->tv_sec += incr_secs;
+       out->tv_nsec += incr_nsecs;
 }
 
 /*

[greearb]

Thanks for trying it out. What OS/kernel were you using to reproduce the increasing delay?
We'll do some more testing and see if we can reproduce.

For the early return, your suggestion won't compile w/out warnings on at least some c compilers since variables
need to be declared at the top of the code block.

[pevik]

Kernel 6.6, on ICMP datagram socket (sysctl net.ipv4.ping_group_range="1 1000").

[yvs2014]

btw,
with the above patch it takes 1sec less than before on 4 packets

% sudo LANG=C builddir/ping/ping -OD -c4 -n 1.1
PING 1.1 (1.0.0.1) 56(84) bytes of data.
[1708707647.909308] no answer yet for icmp_seq=1
[1708707647.912048] 64 bytes from 1.0.0.1: icmp_seq=1 ttl=60 time=2.63 ms
[1708707647.912081] 64 bytes from 1.0.0.1: icmp_seq=2 ttl=60 time=2.55 ms
[1708707648.913852] 64 bytes from 1.0.0.1: icmp_seq=3 ttl=60 time=2.55 ms
[1708707649.913605] 64 bytes from 1.0.0.1: icmp_seq=4 ttl=60 time=2.60 ms

--- 1.1 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 2.545/2.583/2.634/0.036 ms, pipe 2

comparing to std ping

% ping -OD -c4 -n 1.1
PING 1.1 (1.0.0.1) 56(84) bytes of data.
[1708707653.364185] 64 bytes from 1.0.0.1: icmp_seq=1 ttl=60 time=2.57 ms
[1708707654.365836] 64 bytes from 1.0.0.1: icmp_seq=2 ttl=60 time=2.53 ms
[1708707655.366765] 64 bytes from 1.0.0.1: icmp_seq=3 ttl=60 time=2.56 ms
[1708707656.368038] 64 bytes from 1.0.0.1: icmp_seq=4 ttl=60 time=2.69 ms

--- 1.1 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3004ms
rtt min/avg/max/mdev = 2.532/2.588/2.689/0.059 ms

with smaller intervals it looks like not monotonic, for example can jump on 10msec every 10th packet

sudo LANG=C builddir/ping/ping -i0.001 -c100 -OD -n 1.2.3.4
PING 1.2.3.4 (1.2.3.4) 56(84) bytes of data.
[1708709502.502353] no answer yet for icmp_seq=1
[1708709502.502378] no answer yet for icmp_seq=2
[1708709502.512423] no answer yet for icmp_seq=3
[1708709502.512475] no answer yet for icmp_seq=4
[1708709502.512488] no answer yet for icmp_seq=5
[1708709502.512500] no answer yet for icmp_seq=6
[1708709502.512512] no answer yet for icmp_seq=7
[1708709502.512524] no answer yet for icmp_seq=8
[1708709502.512539] no answer yet for icmp_seq=9
[1708709502.512551] no answer yet for icmp_seq=10
[1708709502.512564] no answer yet for icmp_seq=11
[1708709502.512576] no answer yet for icmp_seq=12
[1708709502.522628] no answer yet for icmp_seq=13
[1708709502.522722] no answer yet for icmp_seq=14
[1708709502.522742] no answer yet for icmp_seq=15
[1708709502.522759] no answer yet for icmp_seq=16
[1708709502.522778] no answer yet for icmp_seq=17
[1708709502.522799] no answer yet for icmp_seq=18
[1708709502.522817] no answer yet for icmp_seq=19
[1708709502.522837] no answer yet for icmp_seq=20
[1708709502.522859] no answer yet for icmp_seq=21
[1708709502.522878] no answer yet for icmp_seq=22
[1708709502.532928] no answer yet for icmp_seq=23
[1708709502.532963] no answer yet for icmp_seq=24
[1708709502.532977] no answer yet for icmp_seq=25
[1708709502.532988] no answer yet for icmp_seq=26
[1708709502.533000] no answer yet for icmp_seq=27
[1708709502.533011] no answer yet for icmp_seq=28
[1708709502.533028] no answer yet for icmp_seq=29
[1708709502.533042] no answer yet for icmp_seq=30
[1708709502.533053] no answer yet for icmp_seq=31
[1708709502.533064] no answer yet for icmp_seq=32
[1708709502.543122] no answer yet for icmp_seq=33
[1708709502.543154] no answer yet for icmp_seq=34
[1708709502.543175] no answer yet for icmp_seq=35
[1708709502.543193] no answer yet for icmp_seq=36
[1708709502.543211] no answer yet for icmp_seq=37
[1708709502.543228] no answer yet for icmp_seq=38
[1708709502.543245] no answer yet for icmp_seq=39
[1708709502.543262] no answer yet for icmp_seq=40
[1708709502.543282] no answer yet for icmp_seq=41
[1708709502.543304] no answer yet for icmp_seq=42
[1708709502.543323] no answer yet for icmp_seq=43
[1708709502.553376] no answer yet for icmp_seq=44
[1708709502.553426] no answer yet for icmp_seq=45
[1708709502.553437] no answer yet for icmp_seq=46
[1708709502.553448] no answer yet for icmp_seq=47
[1708709502.553460] no answer yet for icmp_seq=48
[1708709502.553471] no answer yet for icmp_seq=49
[1708709502.553485] no answer yet for icmp_seq=50
[1708709502.553496] no answer yet for icmp_seq=51
[1708709502.553509] no answer yet for icmp_seq=52
[1708709502.553525] no answer yet for icmp_seq=53
[1708709502.563568] no answer yet for icmp_seq=54
[1708709502.563599] no answer yet for icmp_seq=55
[1708709502.563620] no answer yet for icmp_seq=56
[1708709502.563639] no answer yet for icmp_seq=57
[1708709502.563657] no answer yet for icmp_seq=58
[1708709502.563677] no answer yet for icmp_seq=59
[1708709502.563695] no answer yet for icmp_seq=60
[1708709502.563712] no answer yet for icmp_seq=61
[1708709502.563730] no answer yet for icmp_seq=62
[1708709502.563754] no answer yet for icmp_seq=63
[1708709502.573823] no answer yet for icmp_seq=64
[1708709502.573856] no answer yet for icmp_seq=65
[1708709502.573876] no answer yet for icmp_seq=66
[1708709502.573896] no answer yet for icmp_seq=67
[1708709502.573915] no answer yet for icmp_seq=68
[1708709502.573936] no answer yet for icmp_seq=69
[1708709502.573955] no answer yet for icmp_seq=70
[1708709502.573973] no answer yet for icmp_seq=71
[1708709502.573995] no answer yet for icmp_seq=72
[1708709502.574013] no answer yet for icmp_seq=73
[1708709502.584081] no answer yet for icmp_seq=74
[1708709502.584137] no answer yet for icmp_seq=75
[1708709502.584151] no answer yet for icmp_seq=76
[1708709502.584163] no answer yet for icmp_seq=77
[1708709502.584175] no answer yet for icmp_seq=78
[1708709502.584190] no answer yet for icmp_seq=79
[1708709502.584202] no answer yet for icmp_seq=80
[1708709502.584213] no answer yet for icmp_seq=81
[1708709502.584226] no answer yet for icmp_seq=82
[1708709502.584238] no answer yet for icmp_seq=83
[1708709502.594271] no answer yet for icmp_seq=84
[1708709502.594310] no answer yet for icmp_seq=85
[1708709502.594333] no answer yet for icmp_seq=86
[1708709502.594348] no answer yet for icmp_seq=87
[1708709502.594362] no answer yet for icmp_seq=88
[1708709502.594373] no answer yet for icmp_seq=89
[1708709502.594389] no answer yet for icmp_seq=90
[1708709502.594401] no answer yet for icmp_seq=91
[1708709502.594413] no answer yet for icmp_seq=92
[1708709502.594425] no answer yet for icmp_seq=93
[1708709502.594441] no answer yet for icmp_seq=94
[1708709502.604521] no answer yet for icmp_seq=95
[1708709502.604570] no answer yet for icmp_seq=96
[1708709502.604582] no answer yet for icmp_seq=97
[1708709502.604594] no answer yet for icmp_seq=98
[1708709502.604606] no answer yet for icmp_seq=99

--- 1.2.3.4 ping statistics ---
100 packets transmitted, 0 received, 100% packet loss, time 102ms

[greearb]

I think this fixes some of it:

[greearb@v-f36-64 iputils]$ git diff
diff --git a/ping/ping_common.c b/ping/ping_common.c
index 6abc202..e121372 100644
--- a/ping/ping_common.c
+++ b/ping/ping_common.c
@@ -315,7 +315,7 @@ int pinger(struct ping_rts *rts, ping_func_set_st *fset, socket_st *sock)
{
static int oom_count;
int i;

•   long ms_until_xmit = 0;
  

•   long ms_until_xmit = rts->interval;
  
    /* Have we already sent enough? If we have, return an arbitrary positive value. */
    if (rts->exiting || (rts->npackets && rts->ntransmitted >= rts->npackets && !rts->deadline))
  

@@ -325,7 +325,7 @@ int pinger(struct ping_rts *rts, ping_func_set_st *fset, socket_st *sock)
if (rts->cur_time.tv_sec == 0 && rts->cur_time.tv_nsec == 0) {
clock_gettime(CLOCK_MONOTONIC_RAW, &rts->cur_time);
rts->req_xmit_time = rts->cur_time;

•           rts->preload_left = rts->preload;
  

•           rts->preload_left = rts->preload - 1;
    } else {
            struct timespec tv;
  

[greearb@v-f36-64 iputils]$