In a bind9 performance testing I monitored one of named threads with strace for a while, and got below message:
[root@dl580-1 root]# strace -p 1797 -c
Process 1797 attached - interrupt to quit
Process 1797 detached
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
69.11 5.681319 13 442646 137491 futex
19.30 1.586145 13 118467 sendmsg
10.86 0.892565 8 118579 72 recvmsg
0.72 0.059597 3 23725 gettimeofday
0.01 0.000738 15 48 write
------ ----------- ----------- --------- --------- ----------------
100.00 8.220364 703465 137563 total
I traced down the futex errors:
There're many sth. like 'futex(0x818f1bc, FUTEX_WAIT, 585151, NULL) = -1 EAGAIN (Resource temporarily unavailable)'.
At this time the CPU utilization is:
CPU states: cpu user nice system irq softirq iowait idle
total 39.1% 0.0% 39.1% 1.0% 15.9% 0.0% 4.7%
cpu00 30.5% 0.0% 20.3% 4.2% 44.9% 0.0% 0.0%
cpu01 39.8% 0.0% 48.3% 0.0% 5.9% 0.0% 5.9%
cpu02 45.1% 0.0% 41.7% 0.0% 5.9% 0.0% 7.2%
cpu03 41.1% 0.0% 46.1% 0.0% 6.7% 0.0% 5.9%
Mem: 7997692k av, 298108k used, 7699584k free, 0k shrd, 11956k buff
49004k active, 190420k inactive
Swap: 2096472k av, 0k used, 2096472k free 227280k cached
PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND
1795 named 25 0 2960 2960 1892 S 24.9 0.0 29:20 3 named
Do you know what is going on and cause so many system CPU utilization?
thx.
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