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

Willy Tarreau
2007-04-14T13:28:01Z

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 :-/

I'll investigate a bit.

Willy