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From Brian Geffon <briangef...@gmail.com>
Subject High idle cpu utilization on RHEL6
Date Wed, 28 Sep 2011 19:35:44 GMT
Hi,
I'm encountering something strange with ATS3.0.1 on Red Hat Enterprise Linux
6, using a vanilla build with no modules enabled and the default
records.config /w zero entries in the remap file, ATS is idling at very high
CPU (around 15-20%).

root     13509  0.0  0.0  58512  2392 ?        Ss   19:15   0:00
/usr/local/ats3.0.1plain//bin/traffic_cop
nobody   13511  0.1  0.0 480072 16632 ?        Sl   19:15   0:00
/usr/local/ats3.0.1plain/bin/traffic_manager
nobody   13521 ***16.9***  0.1 1584628 114224 ?      Sl   19:15   2:06
/usr/local/ats3.0.1plain/bin/traffic_server -M -A,7:X

So I used strace to try to determine what might be causing this, and here is
what i've found:

[root@machine]# strace -c -p 13521
Process 13521 attached - interrupt to quit
^CProcess 13521 detached
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00    3.589451         796      4510           epoll_wait
------ ----------- ----------- --------- --------- ----------------
100.00    3.589451                  4510           total
[root@machine]#


It appears that it's entirely epoll_wait, and each call is taking 796
microseconds! So I have to concerns with this, first, why would epoll_wait
take such a long amount of time, 796 microseconds seems like a long time,
and more importantly, how could it possibly be called so frequently, does
ATS use a short timeout when doing epoll_waits?

I would really appreciate any feedback regarding this, has anyone else
experienced this? Is there anywhere else I might look to determine the cause
of this? Could this be classified as _normal_ behavior?


Thanks,
Brian

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