TTY task group scheduling

[Kostik Belousov]

On Fri, Nov 19, 2010 at 11:50:49AM +0200, Andriy Gapon wrote:
> on 19/11/2010 11:46 Bruce Cran said the following:
> > [removed current@ and stable@ from the Cc list]
> > 
> > On Fri, 19 Nov 2010 15:41:29 +1100
> > Andrew Reilly <areilly at bigpond.net.au> wrote:
> > 
> >> On Linux.  Have you ever seen those sorts of UI problems on FreeBSD?
> >> I don't watch much video on my systems, but I haven't seen that.
> >> FreeBSD has always been good at keeping user-interactive processes
> >> responsive while compiles or what-not are going on in the background.
> > 
> > I've definitely seen problems when running builds in an xterm. I've
> > often resorted to canceling it and running it on a syscons console
> > instead to improve performance.
> > 
> 
> So, what was it a problem with scheduler or with, e.g., "something X"
> being too slow rendering glyphs? Who can tell...

Probably will pay a lot in negative karma by posting anything in the
thread. But I can confirm your words, that tty->xterm->X server chain
of output indeed significantly slows down the build processes.

I usually never start build in the barebone xterm, always running screen
under xterm. make -j 10 on 4 core/HTT cpu slows up to a half, from my
unscientific impression, when run in the active screen window. Switching
to other window in screen significantly speeds it up (note the prudent
omission of any measured numbers).
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