Re: interactive task starvation

Willy Tarreau
2006-03-21T14:44:30Z

On Tue, Mar 21, 2006 at 03:32:40PM +0100, Ingo Molnar wrote:
>
> * Con Kolivas <kernel@kolivas.org> wrote:
>
> > On Wednesday 22 March 2006 01:28, Mike Galbraith wrote:
> > > On Wed, 2006-03-22 at 01:19 +1100, Con Kolivas wrote:
> > > > What you're fixing with unfairness is worth pursuing. The 'ls' issue just
> > > > blows my mind though for reasons I've just said. Where are the magic
> > > > cycles going when nothing else is running that make it take ten times
> > > > longer?
> > >
> > > What I was talking about when I mentioned scrolling was rendering.
> >
> > I'm talking about the long standing report that 'ls' takes 10 times
> > longer on 2.6 90% of the time you run it, and doing 'ls | cat' makes
> > it run as fast as 2.4. This is what Willy has been fighting with.
>
> ah. That's i think a gnome-terminal artifact - it does some really
> stupid dynamic things while rendering, it 'skips' certain portions of
> rendering, depending on the speed of scrolling. Gnome 2.14 ought to have
> that fixed i think.

Ah no, I never use those montruous environments ! xterm is already heavy.
don't you remember, we found that doing "ls" in an xterm was waking the
xterm process for every single line, which in turn woke the X server for
a one-line scroll, while adding the "|cat" acted like a buffer with batched
scrolls. Newer xterms have been improved to trigger jump scroll earlier and
don't exhibit this behaviour even on non-patched kernels. However, sshd
still shows the same problem IMHO.

> Ingo

Cheers,
Willy