Re: Why is real time pinging not possible with RT kernels?

rolf.freitag
2017-06-17T08:38:02Z

Hi,

Gesendet: Montag, 12. Juni 2017 um 18:45 Uhr
Von: "Chris Friesen" <chris.friesen@windriver.com>
...
>> A few notes on what you have done:
>>
>> * ionice doesn't affect network I/O.
>> * renice does not set real-time priorities.
>
> Good point...the OP probably wants something like "sudo chrt <prio> <cmd> ...."

Ok, i added chrt in the script:

ionice -c3 -p $$
renice +19 -p $$
chrt -f -p 99 $$
ping -q -s 28 -l 1 -p 0f1e2d3c4b5a6978 -i 0.001 localhost

and now the worst case latency is about twice the value measured with cyclictest:

27893223 packets transmitted, 27893223 received, 0% packet loss, time 27921273ms
rtt min/avg/max/mdev = 0.022/0.023/0.280/0.006 ms

>> * You don't do anything with memory locking. What happens
>> if memory in your program gets paged out then is required?

I use much RAM and no swap, so i have implicit memory locking.

Regards,

Rolf