[erlang-questions] UDP receive performance

[Lukas Larsson]

Can you run perf with "--call-graph dwarf" and see which functions it is
that call memmove?

On Thu, May 24, 2018 at 12:21 PM, Danil Zagoskin <z@REDACTED> wrote:

> Yes, I've built a fresh master today (Erlang/OTP 21 [RELEASE CANDIDATE 1]
> [erts-9.3.1]), and nothing has changed.
>
> On Thu, May 24, 2018 at 1:17 PM, Sergej Jurečko <sergej.jurecko@REDACTED>
> wrote:
>
>> 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> 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
>>>
>>> >
>>> > 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        [.] __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
>>>
>>> > _______________________________________________
>>> > erlang-questions mailing list
>>> > erlang-questions@REDACTED
>>> > http://erlang.org/mailman/listinfo/erlang-questions
>>>
>>>
>>> --
>>>
>>> / Raimo Niskanen, Erlang/OTP, Ericsson AB
>>> _______________________________________________
>>> erlang-questions mailing list
>>> erlang-questions@REDACTED
>>> http://erlang.org/mailman/listinfo/erlang-questions
>>>
>>
>>
>>
>> --
>> Danil Zagoskin | z@REDACTED
>> _______________________________________________
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>> http://erlang.org/mailman/listinfo/erlang-questions
>>
>>
>>
>
>
> --
> Danil Zagoskin | z@REDACTED
>
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