Re: [PATCH] Staircase scheduler v7.4

Willy Tarreau
2004-06-25T22:29:21Z

Hi Con,

although I was one of those who complained a lot about the 2.6 scheduler,
and still don't use it because of its sluggishness under X11, I'm impressed
by your work here. I've tried the good old test which was *very* sluggish
on a vanilla 2.6 :

# for i in $(seq 1 20); do xterm -e sh -c "while :; do locate /;done" & done

It opens 20 xterms constantly listing my slocate database (vmstat shows
no I/O).

Under vanilla 2.6 (up to 2.6.4 at least), some of these xterms would freeze
for up to about 10 seconds IIRC during redrawing, with incomplete lines, etc...
This still happens with your patch and /p/s/k/interactive=0, but to a lesser
extent it seems. But it does not happen anymore with interactive=1, hence the
progress !

However, you warned us that the nice parameter was very sensible. Indeed,
it *is* ! When my window manager (ctwm, very light) is at 0, just like the
script above, the windows appear slowly and irregularly on the screen,
but this takes no more than 15s, during which windows get no title, then
suddenly they get everything right. If I renice the WM at +1, I see no
more than 5 windows on the screen with no decoration at all, and then I
cannot even change the focus to another one anymore. Then, as soon as I
change the WM's nice value to -1, suddenly all remaining windows appear
with their title. The same is true if I start the script with the WM at
-1 initially. It's just as if the nice value was directly used as the
priority in a queue.

Oh and BTW, this is an SMP box (dual athlon).

Well, I see there is some very good progress ! Please keep up the good
work !

Cheers,
Willy