cygrunsrv + sshd + rsync = 20 times too slow -- throttled?

[Corinna Vinschen]

On Sep 14 17:08, Takashi Yano wrote:
> @@ -54,8 +54,12 @@ fhandler_pipe::set_pipe_non_blocking (bool nonblocking)
>    FILE_PIPE_INFORMATION fpi;
>  
>    fpi.ReadMode = FILE_PIPE_BYTE_STREAM_MODE;
> -  fpi.CompletionMode = nonblocking ? FILE_PIPE_COMPLETE_OPERATION
> -    : FILE_PIPE_QUEUE_OPERATION;
> +  /* If query_hdl is set, write pipe should check reader_closed()
> +     while raw_read(). If the pipe is blocking, raw_write() stops
> +     at NtWriteFile() and loses the chance to check it. Therefore,
> +     always set write pipe to non-blocking. */
> +  fpi.CompletionMode = (nonblocking || query_hdl)
> +    ? FILE_PIPE_COMPLETE_OPERATION : FILE_PIPE_QUEUE_OPERATION;
>    status = NtSetInformationFile (get_handle (), &io, &fpi, sizeof fpi,
>  				 FilePipeInformation);
>    if (!NT_SUCCESS (status))

I don't quite follow the argument.  Blocking pipes are using
asynchronous IO, so they are in fact not blocking calls on the
OS level.  After calling NtWriteFile, the blocking variation
will go into the subsequent

  waitret = cygwait (evt, INFINITE, cw_cancel | cw_sig);

So, wouldn't you get the same effect by keeping the pipe in
FILE_PIPE_QUEUE_OPERATION mode and just add a timeout to the above
cygwait call and handle select_sem in a not yet existing WAIT_TIMEOUT
conditional?


Corinna


P.S.: Maybe the cygwait call is just too simple.  It would be nice if it
      had been defined to take an array of handles, rather than just a
      single handle.  Another change we should keep in mind.