Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS]

Ingo Molnar
2007-04-14T16:19:41Z

* Willy Tarreau <w@1wt.eu> wrote:

> On Sat, Apr 14, 2007 at 03:01:01PM +0200, Willy Tarreau wrote:
> >
> > Well, I'll stop heating the room for now as I get out of ideas about how
> > to defeat it.
>
> Ah, I found something nasty.
> If I start large batches of processes like this :
>
> $ for i in $(seq 1 1000); do ./scheddos2 4000 4000 & done
>
> the ramp up slows down after 700-800 processes, but something very
> strange happens. If I'm under X, I can switch the focus to all xterms
> (the WM is still alive) but all xterms are frozen. On the console,
> after one moment I simply cannot switch to another VT anymore while I
> can still start commands locally. But "chvt 2" simply blocks. SysRq-K
> killed everything and restored full control. Dmesg shows lots of :

> SAK: killed process xxxx (scheddos2): process_session(p)==tty->session.
>
> I wonder if part of the problem would be too many processes bound to
> the same tty :-/

hm, that's really weird. I've Cc:-ed the tty experts (Erik, Jiri, Alan),
maybe this description rings a bell with them?

Ingo