Hi all,
I'm using Trafficserver 4.2.0 on Debian Wheezy, with raw disks as cache
on VMware virtual machines. Activity level is a bit less than 400
requests per seconds with a cache hit ratio greater than 99%.
On a regular basis, traffic_server process (ET_NET 0) starts to heavily
use CPU (more than 75%).
That's fine for me since it's the only process on the virtual machine.
But, the problem is that most of this CPU usage concerns IO Wait.
Running command iostat -m 1 confirms that all IO Wait operations are
related to cache raw devices.
Restarting trafficserver service fixes the problem... till next time.
I tried to strace the process and got plenty of:
epoll_wait(21, {{EPOLLIN, {u32=301105424, u64=47154747048208}}}, 32768,
10) = 1
read(14, "\1\0\0\0\0\0\0\0", 8) = 8
futex(0x2ae31800d07c, FUTEX_WAKE_OP_PRIVATE, 1, 1, 0x2ae31800d078,
{FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1}) = 1
futex(0x2ae31800d050, FUTEX_WAKE_PRIVATE, 1) = 1
Found nothing strange in diags.log, manager.log or traffic.out log files.
Any idea welcome,
Regards,
Jean-Baptiste Favre
