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

[Takashi Yano]

On Wed, 15 Sep 2021 11:57:44 +0200
Corinna Vinschen wrote:
> On Sep 15 09:59, Takashi Yano wrote:
> > @@ -633,17 +633,15 @@ pipe_data_available (int fd, fhandler_base *fh, HANDLE h, bool writing)
> >        /* Note: Do not use NtQueryInformationFile() for query_hdl because
> >  	 NtQueryInformationFile() seems to interfere with reading pipes
> >  	 in non-cygwin apps. Instead, use PeekNamedPipe() here. */
> 
> ...so we're not using NtQueryInformationFile on the query_hdl...
> 
> > -      if (fh->get_device () == FH_PIPEW)
> > +      if (fh->get_device () == FH_PIPEW && fpli.WriteQuotaAvailable == 0)
> >  	{
> >  	  HANDLE query_hdl = ((fhandler_pipe *) fh)->get_query_handle ();
> > -	  if (query_hdl)
> > -	    {
> > -	      DWORD nbytes_in_pipe;
> > -	      PeekNamedPipe (query_hdl, NULL, 0, NULL, &nbytes_in_pipe, NULL);
> > -	      fpli.WriteQuotaAvailable = fpli.InboundQuota - nbytes_in_pipe;
> > -	    }
> > -	  else
> > +	  if (!query_hdl)
> > +	    return 1; /* We cannot know actual write pipe space. */
> > +	  DWORD nbytes_in_pipe;
> > +	  if (!PeekNamedPipe (query_hdl, NULL, 0, NULL, &nbytes_in_pipe, NULL))
> >  	    return 1;
> > +	  fpli.WriteQuotaAvailable = fpli.InboundQuota - nbytes_in_pipe;
> >  	}
> >        if (fpli.WriteQuotaAvailable > 0)
> 
> ...but we're unconditionally using NtQueryInformationFile at the start
> of pipe_data_available.  If this is the read side of the pipe, isn't
> there a chance that another (non-Cygwin) process is performing a blocking
> read and this call will hang?

I will check that.

> Btw., this doesn't work as expected:
> 
> $ yes | /cygdrive/c/Windows/System32/more
> 
> It just hangs until pressing Ctrl-C.  Is that expected currently?

Indeed. However, this also does not work in cygwin 3.2.0,

while
yes AAAAAA | /cygdrive/c/Windows/System32/more
works...

I am not sure why so far.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>