From: David.Kastrup@t-online.de (David Kastrup)
Cc: emacs-devel@gnu.org
Subject: Re: Fix for slow process output processing (please test).
Date: 16 Dec 2003 12:51:45 +0100 [thread overview]
Message-ID: <x5oeu9m14e.fsf@lola.goethe.zz> (raw)
In-Reply-To: <m3fzflcb8b.fsf@kfs-l.imdomain.dk>
storm@cua.dk (Kim F. Storm) writes:
> David.Kastrup@t-online.de (David Kastrup) writes:
>
> > > David Kastrup and others have reported very slow processing of process
> > > output, particularly with the Linux kernel's scheduler giving emacs
> > > too much attention while starving the processing producing the output.
> > >
> > > Below is a patch which introduces a small delay on reading output from
> > > such processes, without using global delays in processing other events
> > > (this is done by temporarily removing the process' file descriptor from
> > > the call to select and use a short timeout on the select instead.
> >
> > I have glanced over that patch. There is one problem I see with it:
> > if indeed the generating process is able to produce lots of data with
> > a single write call, Emacs will be throttling its input without a
> > purpose.
>
> With the patch, emacs only throttles if it reads less than 1024 bytes
> at a time from the process -- i.e. if the process is unable to produce
> data fast enough to fill emacs's read buffer.
>
> So if you have a process which manages to write a lot of data in one
> write, emacs should happily read that data with no throttling.
And if we have a process that writes in small chunks but with very
good CPU utilization (something like dd if=/dev/zero obs=1), then we
will alternate between reading 8192 (or whatever the pipe size is) and
1 byte. Of course vastly preferable to alternating between reading 1
byte and 1 byte.
--
David Kastrup, Kriemhildstr. 15, 44793 Bochum
next prev parent reply other threads:[~2003-12-16 11:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-16 1:21 Fix for slow process output processing (please test) Kim F. Storm
2003-12-16 2:14 ` David Kastrup
2003-12-16 3:34 ` David Kastrup
2003-12-16 10:23 ` Kim F. Storm
2003-12-16 11:51 ` David Kastrup [this message]
2003-12-16 13:24 ` Kim F. Storm
2004-01-03 15:12 ` David Kastrup
2004-01-04 23:00 ` Kim F. Storm
2004-01-03 22:07 ` Eric Hanchrow
2004-01-04 22:42 ` Kim F. Storm
2004-01-05 15:57 ` David Kastrup
2004-01-05 19:09 ` Eli Zaretskii
2004-01-05 19:39 ` David Kastrup
2004-01-05 19:52 ` Jason Rumney
2004-01-05 23:28 ` Kim F. Storm
2004-01-05 23:16 ` Jason Rumney
2004-01-05 23:44 ` David Kastrup
2004-01-06 0:23 ` Jason Rumney
2004-01-07 0:40 ` Kim F. Storm
2004-01-05 23:35 ` Kim F. Storm
2004-01-05 22:50 ` David Kastrup
2004-01-06 0:09 ` Kim F. Storm
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