From: Con Kolivas <kernel@kolivas.org>
To: Alex Riesen <fork0@users.sf.net>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH]O18.1int
Date: Tue, 26 Aug 2003 08:48:23 +1000
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Cc: William Lee Irwin III <wli@holomorphy.com>
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On Tue, 26 Aug 2003 07:02, Alex Riesen wrote:
> Alex Riesen, Mon, Aug 25, 2003 12:21:33 +0200:
> > > > > XEmacs still spins after running a background job like make or
> > > > > grep. It's fine if I reverse patch-O16.2-O16.3. The spinning
> > > > > doesn't happen as often, or as long time as with O16.3, but it's
> > > > > there and it's irritating.
> > > >
> > > > another example is RXVT (an X terminal emulator). Starts spinnig
> > > > after it's child has exited. Not always, but annoyingly often. System
> > > > is almost locked while it spins (calling select).
> > >
> > > What does vanilla kernel do with these apps running? Both immediately
> > > after the apps have started up and some time (>1 min) after they've
> > > been running?
> >
> > cannot test atm. Will do in 10hours.
> > RXVT behaved sanely (or probably spin-effect is very rare) in 2.4 (with
> > O(1) alone and your 2.4 patches) and plain 2.6-test1.
>
> Sorry, I have to postpone this investigation. No time on the machine.
>
> I try to describe the behaviour of rxvt as best as I can below.
>
> Afaics, the application (rxvt) just sleeps at the beginning waiting for
> input from X. As every terminal would do. At some point its inferior
> process finishes, but it fails to notice this spinning madly in the
> internal loop calling select, which returns immediately (because other
> side of pty was closed. That is the error in rxvt). Probably it has
> accumulated enough "priority" up to this moment to block other
> applications (window manager, for example) when it suddenly starts running?

Something like that. Interesting you point out select as wli was 
profiling/tracing the mozilla/acroread plugin combination that spins on wait 
and also found select was causing grief. It was calling select with a 15ms 
timeout and X was getting less than 5ms to do it's work and respond and it 
was repeatedly timing out. Seems a common link there.

Con

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