----- Original Message -----
> On Wed, Sep 28, 2011 at 3:35 PM, Brian Geffon <briangeffon@gmail.com>
> wrote:
>
> > 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?
> >
> >
> >
> It is working as designed. The epoll timeout is set to 0 or 10 msec
> on
> linux. Could there be very little or no load going through this
> instance?
> That would explain why you are only seeing epoll_wait. In that case
> there
> isn't really anything wrong, the process is just burning through
> epoll_waits
> looking for something to do when nothing is available. Once the
> process
> starts taking enough traffic, you will start to see user space and
> other
> kernel functions start to take cpu time.
That still doesn't quite explain the high load on an Idle system.
Brian: Do you happen to have SELinux enabled?
> Sridhar
i
--
Igor Galić
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Mail: i.galic@brainsware.org
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