CPU underload

[Eugene Grosbein]

On 01.11.2015 03:10, Adrian Chadd wrote:
> Hm, okay. Try doing ping -i 0.01 (ie, every 10ms.) I wonder if it's
> happening more frequently and we're hitting sampling bias.

Now without HWPMC_MIPS_BACKTRACE and with full CPU load
it started dropping packets under load, both with "-i 0.1" and "-i 0.01":


# ping -c 450 -s 1472 -i 0.1 192.168.3.1
[skip]
450 packets transmitted, 425 packets received, 5.6% packet loss
round-trip min/avg/max/stddev = 0.285/0.715/7.184/0.383 ms

# ping -c 4500 -s 1472 -i 0.01 192.168.3.1
[skip]
4500 packets transmitted, 4284 packets received, 4.8% packet loss
round-trip min/avg/max/stddev = 0.238/0.725/7.677/0.389 ms

In the latter case:

# grep -v 'time=[01]' log
PING 192.168.3.1 (192.168.3.1): 1472 data bytes
1480 bytes from 192.168.3.1: icmp_seq=5 ttl=64 time=7.017 ms
1480 bytes from 192.168.3.1: icmp_seq=101 ttl=64 time=6.517 ms
1480 bytes from 192.168.3.1: icmp_seq=490 ttl=64 time=2.121 ms
1480 bytes from 192.168.3.1: icmp_seq=684 ttl=64 time=2.640 ms
1480 bytes from 192.168.3.1: icmp_seq=1165 ttl=64 time=2.987 ms
1480 bytes from 192.168.3.1: icmp_seq=1453 ttl=64 time=6.688 ms
1480 bytes from 192.168.3.1: icmp_seq=2419 ttl=64 time=2.769 ms
1480 bytes from 192.168.3.1: icmp_seq=2515 ttl=64 time=4.655 ms
1480 bytes from 192.168.3.1: icmp_seq=2612 ttl=64 time=4.706 ms
1480 bytes from 192.168.3.1: icmp_seq=2902 ttl=64 time=7.677 ms
1480 bytes from 192.168.3.1: icmp_seq=2998 ttl=64 time=7.548 ms
1480 bytes from 192.168.3.1: icmp_seq=3095 ttl=64 time=3.359 ms
1480 bytes from 192.168.3.1: icmp_seq=3191 ttl=64 time=5.047 ms
1480 bytes from 192.168.3.1: icmp_seq=3483 ttl=64 time=7.278 ms
1480 bytes from 192.168.3.1: icmp_seq=3579 ttl=64 time=7.192 ms
1480 bytes from 192.168.3.1: icmp_seq=3870 ttl=64 time=6.866 ms
1480 bytes from 192.168.3.1: icmp_seq=3967 ttl=64 time=4.824 ms
1480 bytes from 192.168.3.1: icmp_seq=4063 ttl=64 time=4.385 ms
1480 bytes from 192.168.3.1: icmp_seq=4352 ttl=64 time=7.525 ms
1480 bytes from 192.168.3.1: icmp_seq=4450 ttl=64 time=2.993 ms

--- 192.168.3.1 ping statistics ---
4500 packets transmitted, 4284 packets received, 4.8% packet loss
round-trip min/avg/max/stddev = 0.238/0.725/7.677/0.389 ms