[erlang-questions] UDP receive performance

[Sergej Jurečko]

OTP-21 rc1 has enhanced IO scalability. Have you tried if it is any better? UDP performance in Erlang was never great... 

Regards,
Sergej

> On 24 May 2018, at 12:03, Danil Zagoskin <z@REDACTED> wrote:
> 
> Yes, we have {read_packets, 100} in receive socket options.
> 
> On Thu, May 24, 2018 at 10:23 AM, Raimo Niskanen <raimo+erlang-questions@REDACTED <mailto:raimo+erlang-questions@REDACTED>> wrote:
> On Wed, May 23, 2018 at 06:28:55PM +0300, Danil Zagoskin wrote:
> > Hi!
> > 
> > We have a performance problem receiving lots of UDP traffic.
> > There are a lot (about 70) of UDP receive processes, each handling about 1
> > to 10 megabits of multicast traffic, with {active, N}.
> 
> Whenever someone has UDP receive performance problems one has to ask if you
> have seen the Erlang socket option {read_packets,N}?
> 
> See http://erlang.org/doc/man/inet.html#setopts-2 <http://erlang.org/doc/man/inet.html#setopts-2>
> 
> > 
> > msacc summary on my OSX laptop, build from OTP master
> > c30309e799212b080c39ee2f91af3f9a0383d767 (Apr 19):
> > 
> > 
> >         Thread    alloc      aux      bifbusy_wait check_io emulator
> >    ets       gc  gc_full      nif    other     port     send    sleep
> >  timers
> >      scheduler   30.02%    0.92%    2.86%   24.66%    0.01%    9.61%
> >  0.03%    1.25%    0.20%    0.13%    2.34%    9.33%    0.41%   17.78%
> >   0.44%
> > 
> > 
> > Linux production server behaves the same way (we do not have extended msacc
> > there yet, so most of alloc goes to port).
> > 
> > perf top (on Linux production) says there's a lot of unaligned memmove:
> > 
> >   69.76%  libc-2.24.so <http://libc-2.24.so/>        [.] __memmove_sse2_unaligned_erms
> >    6.13%  beam.smp            [.] process_main
> >    2.02%  beam.smp            [.] erts_schedule
> >    0.87%  [kernel]            [k] copy_user_enhanced_fast_string
> > 
> > 
> > I'll try to make a minimal example for this.
> > Maybe there are simple recommendations on optimizing this kind of load?
> > 
> > -- 
> > Danil Zagoskin | z@REDACTED <mailto:z@REDACTED>
> 
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> 
> 
> -- 
> 
> / Raimo Niskanen, Erlang/OTP, Ericsson AB
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> 
> 
> -- 
> Danil Zagoskin | z@REDACTED <mailto:z@REDACTED>_______________________________________________
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