SO_REUSEPORT

[SplitIce]

Ok, I have a virtual machine which has a residual kernel of 3.16.0-0.bpo.4
(Debian wheezy-backport's) available I confirmed the issue is replicatable
on that machine too.

The testing methodology is using ab from 12 other remote servers (hopefully
in order to prevent collisions) at a fairly low rate of 1r/s (the virtual
machine with this older kernel is not particularly large). During this
testing zero requests where received at one sampled process, while the
first process showed approximately 10% CPU usage.

Regards,
Mathew



On Wed, Nov 25, 2015 at 12:42 AM, Valentin V. Bartenev <vbart at nginx.com>
wrote:

> On Wednesday 25 November 2015 00:25:19 SplitIce wrote:
> > Hi all,
> >
> > I couldn't find anything in the mailing list about this issue, surely we
> > are not the only one?
> >
> > When activating reuseport I am seeing all requests be served from a
> single
> > nginx process. All others are just idling (SIGALARM interruption of
> > epoll_wait / epoll_wait timeout according to strace).
> >
> > Process 442 attached - interrupt to quit
> > epoll_wait(60, 8225010, 512, 4294967295) = -1 EINTR (Interrupted system
> > call)
> > --- SIGALRM (Alarm clock) @ 0 (0) ---
> > rt_sigreturn(0xe)                       = -1 EINTR (Interrupted system
> call)
> > epoll_wait(60, 8225010, 512, 4294967295) = -1 EINTR (Interrupted system
> > call)
> > --- SIGALRM (Alarm clock) @ 0 (0) ---
> >
> >
> >
> > This only occurs with reuseport, as soon as it is disabled the load is
> > correctly distributed again.
> >
> > Configuration:
> > worker_processes 12; # 2x8 cores on server
> > multiple server blocks on different IP's and ports with reuseaddr.
> > Linux kernel: 3.18.20
> >
> > Server nic has interrupts over all cores:
> >
> > # sudo ethtool -S eth0 |grep rx | grep pack
> >      rx_packets: 11244443305
> >      rx_queue_0_packets: 1381842455
> >      rx_queue_1_packets: 1373383493
> >      rx_queue_2_packets: 1490287703
> >      rx_queue_3_packets: 1440591930
> >      rx_queue_4_packets: 1378550073
> >      rx_queue_5_packets: 1373473609
> >      rx_queue_6_packets: 1437806438
> >
> >
> > We have also experimented with disabling iptables and anything else on
> the
> > server that could be interfering. I have also loaded it onto three other
> > fresh servers with the same kernel (same OS image), but with different
> nic
> > cards (with and without multiple rx queues) with no changes.
> >
> > This has me stumped. Ideas?
> >
>
> You should try another kernel.
>
>   wbr, Valentin V. Bartenev
>
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