Sawtooth ping RTT on RPi

[Adrian Chadd]

CAn you run that for a minute or two, just to capture a few cycles?



Adrian

On 8 May 2013 01:59, Peter Jeremy <peter at rulingia.com> wrote:
> I've noticed a sawtooth-shaped cyclic pattern in ping RTTs to my RPi
> (running r249590M):
> 64 bytes from 192.168.123.231: icmp_seq=22 ttl=64 time=1.321 ms
> 64 bytes from 192.168.123.231: icmp_seq=23 ttl=64 time=10.312 ms
> 64 bytes from 192.168.123.231: icmp_seq=24 ttl=64 time=9.328 ms
> 64 bytes from 192.168.123.231: icmp_seq=25 ttl=64 time=8.335 ms
> 64 bytes from 192.168.123.231: icmp_seq=26 ttl=64 time=7.411 ms
> 64 bytes from 192.168.123.231: icmp_seq=27 ttl=64 time=6.448 ms
> 64 bytes from 192.168.123.231: icmp_seq=28 ttl=64 time=5.497 ms
> 64 bytes from 192.168.123.231: icmp_seq=29 ttl=64 time=4.508 ms
> 64 bytes from 192.168.123.231: icmp_seq=30 ttl=64 time=3.540 ms
> 64 bytes from 192.168.123.231: icmp_seq=31 ttl=64 time=2.588 ms
> 64 bytes from 192.168.123.231: icmp_seq=32 ttl=64 time=1.635 ms
> 64 bytes from 192.168.123.231: icmp_seq=33 ttl=64 time=0.738 ms
> 64 bytes from 192.168.123.231: icmp_seq=34 ttl=64 time=9.770 ms
> 64 bytes from 192.168.123.231: icmp_seq=35 ttl=64 time=8.805 ms
> 64 bytes from 192.168.123.231: icmp_seq=36 ttl=64 time=7.833 ms
> 64 bytes from 192.168.123.231: icmp_seq=37 ttl=64 time=6.843 ms
> 64 bytes from 192.168.123.231: icmp_seq=38 ttl=64 time=5.869 ms
>
> This doesn't appear with Linux (which has a RTT of 0.42ms with
> very little variance).
>
> What is causing the RTT pattern on FreeBSD?
> Haw does Linux manage to respond so much faster?
>
> --
> Peter Jeremy