Hi Ingo, On Sun, Apr 15, 2007 at 07:55:55PM +0200, Ingo Molnar wrote: > > * Willy Tarreau <[EMAIL PROTECTED]> wrote: > > > Well, since I merged the fair-fork patch, I cannot reproduce (in fact, > > bash forks 1000 processes, then progressively execs scheddos, but it > > takes some time). So I'm rebuilding right now. But I think that Linus > > has an interesting clue about GPM and notification before switching > > the terminal. I think it was enabled in console mode. I don't know how > > that translates to frozen xterms, but let's attack the problems one at > > a time. > > to debug this, could you try to apply this add-on as well: > > http://redhat.com/~mingo/cfs-scheduler/sched-fair-print.patch > > with this patch applied you should have a /proc/sched_debug file that > prints all runnable tasks and other interesting info from the runqueue.
I don't know if you have seen my mail from yesterday evening (here). I found that changing keventd prio fixed the problem. You may be interested in the description. I sent it at 21:01 (+200). > [ i've refreshed all the patches on the CFS webpage, so if this doesnt > apply cleanly to your current tree then you'll probably have to > refresh one of the patches.] Fine, I'll have a look. I already had to rediff the sched-fair-fork patch last time. > The output should look like this: > > Sched Debug Version: v0.01 > now at 226761724575 nsecs > > cpu: 0 > .nr_running : 3 > .raw_weighted_load : 384 > .nr_switches : 13666 > .nr_uninterruptible : 0 > .next_balance : 4294947416 > .curr->pid : 2179 > .rq_clock : 241337421233 > .fair_clock : 7503791206 > .wait_runtime : 2269918379 > > runnable tasks: > task | PID | tree-key | -delta | waiting | switches > ----------------------------------------------------------------- > + cat 2179 7501930066 -1861140 1861140 2 > loop_silent 2149 7503010354 -780852 0 911 > loop_silent 2148 7503510048 -281158 280753 918 Nice. > now for your workload the list should be considerably larger. If there's > starvation going on then the 'switches' field (number of context > switches) of one of the tasks would never increase while you have this > 'cannot switch consoles' problem. > > maybe you'll have to unapply the fair-fork patch to make it trigger > again. (fair-fork does not fix anything, so it probably just hides a > real bug.) > > (i'm meanwhile busy running your scheddos utilities to reproduce it > locally as well :) I discovered I had the frame-buffer enabled (I did not notice it first because I do not have the logo and the resolution is the same as text). It's matroxfb with a G400, if that can help. It may be possible that it needs some CPU that it cannot get to clear the display before switching, I don't know. However I won't try this right now, I'm deep in userland at the moment. Regards, Willy - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
