Re: pipe performance problem

[thomas <tom at huno dot net>]

thomas <tom@huno.net> wrote:

>    26  245082 [main] dd 3100 readv: DEBUG 1.a syscalls.cc
>    23  245105 [main] dd 3100 readv: DEBUG 1.b syscalls.cc
>    23  245128 [main] dd 3100 readv: DEBUG 2.a syscalls.cc
>    23  245151 [main] dd 3100 readv: readv (0, 0x240FD9C, 1) blocking, sigcatchers 4
>    24  245175 [main] dd 3100 readv: DEBUG 2.b syscalls.cc
> 10508  255683 [main] dd 3100 peek_pipe: DEBUG 7.0 select.cc
>    76  255759 [main] dd 3100 peek_pipe: /dev/piper, ready for read
>    27  255786 [main] dd 3100 peek_pipe: DEBUG 7.1 select.cc
>    25  255811 [main] dd 3100 peek_pipe: DEBUG 7.2 select.cc
>    26  255837 [main] dd 3100 fhandler_base::ready_for_read: read_ready 1, avail 1
>    25  255862 [main] dd 3100 readv: DEBUG 2.d syscalls.cc

> If i'm not misinterpreting things readv (DEBUG 2.b) is actually the
> problem and not peek_pipe. DEBUG 7.0 is always there, even if there is
> no delay, so that cannot be it.

After i sent the mail i saw that DEBUG 2.b is of course always there
too. But still according to the timeline it must be it. But just for
completeness, here is the DEBUG 7.x stuff from select.cc (line 464):

  if (n > 0 && s->read_selected)
    {
      debug_printf ("DEBUG 7.0 select.cc");
      select_printf ("%s, ready for read", fh->get_name ());
      debug_printf ("DEBUG 7.1 select.cc");
      gotone += s->read_ready = true;
      debug_printf ("DEBUG 7.2 select.cc");
    }

thomas


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