I'm running a Mojolicious UI in daemon mode on a PowerPC embedded system
(running Wind River Linux, perl 5.22.0, kernel 4.1.21) and notice
surprisingly high CPU usage on a totally idle UI.
I can see that there are two processes. Each process is in a polling loop
with 10ms timeout. I don't expect to see two processes here, so I wonder
whether this is normal or abnormal behaviour. If it is normal behaviour,
can I tune down the 10ms timeout to something longer? I would like to see
the process block until there is actual work to do.
root@10:/service# ps fax | grep index.daemon-5
1418 pts/1 S+ 0:00 \_ grep index.daemon
19303 ? Ssl 24:24 /etc/e-smith/web/functions/index.daemon.cgi
24397 ? Ssl 20:54 \_ /etc/e-smith/web/functions/index.daemon.cgi
root@10:/service# strace -p19303 -tt 2>&1 | head -5
Process 19303 attached
17:05:08.095154 restart_syscall(<... resuming interrupted call ...>) = 0
17:05:08.104465 poll([{fd=21, events=POLLIN|POLLPRI|POLLOUT}], 1, 9) = 0
(Timeout)
17:05:08.116478 poll([{fd=21, events=POLLIN|POLLPRI|POLLOUT}], 1, 10) = 0
(Timeout)
17:05:08.130120 poll([{fd=21, events=POLLIN|POLLPRI|POLLOUT}], 1, 9) = 0
(Timeout)
root@10:/service# strace -p24397 -tt 2>&1 | head -5
Process 24397 attached
17:05:12.888643 restart_syscall(<... resuming interrupted call ...>) = 0
17:05:12.894814 poll([{fd=21, events=POLLIN|POLLPRI|POLLOUT}], 1, 10) = 0
(Timeout)
17:05:12.908082 poll([{fd=21, events=POLLIN|POLLPRI|POLLOUT}], 1, 10) = 0
(Timeout)
17:05:12.920771 poll([{fd=21, events=POLLIN|POLLPRI|POLLOUT}], 1, 10) = 0
(Timeout)
root@10:/service# top | head -12
top - 17:09:31 up 9 days, 7:59, 4 users, load average: 0.73, 0.59, 0.60
Tasks: 98 total, 1 running, 95 sleeping, 0 stopped, 2 zombie
%Cpu(s): 12.9 us, 5.7 sy, 3.8 ni, 75.7 id, 1.8 wa, 0.0 hi, 0.1 si,
0.0 st
KiB Mem : 995536 total, 5428 free, 317100 used, 673008
buff/cache
KiB Swap: 65532 total, 65448 free, 84 used. 594360 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1440 root 20 0 3852 2280 1924 R 24.0 0.2 0:00.13 top
508 root 20 0 134908 69156 13896 S 12.0 6.9 465:50.05
call_control
19303 root 20 0 87812 37720 4148 S 8.0 3.8 24:45.37
/etc/e-smith/we
24397 root 20 0 87788 37184 3552 S 8.0 3.7 21:13.65
/etc/e-smith/we
425 root 20 0 16068 10284 3640 S 4.0 1.0 33:32.22 snmpd
