Re: Native preemption is the culprit [was Re: today's CURRENT lockups]

On Sat, 10 Jul 2004 02:12:39 -0500
Jon Noack <noackjr_at_alumni.rice.edu> wrote:
> On 07/10/04 02:06, Ariff Abdullah wrote:
> > On Sat, 10 Jul 2004 01:18:06 -0400 (EDT)
> > Robert Watson <rwatson_at_freebsd.org> wrote:
> >> FYI, UP+SCHED_ULE with PREEMPTION hung within three seconds of 
> >> starting the benchmark. Without PREEMPTION it seems to run fine.
> >> 
> >> So it looks like either PREEMPTION has a problem, or it's
> >> triggering an existing problem elsewhere. If it's only one
> >problem,> it seems not to depend on either SMP/UP or the scheduler
> >choice. If> it's multiple problems, who knows :-). As the MySQL
> >test relies on > threading, we could be looking at an edge case
> >involving threading > and scheduling/preemption-- the other reports
> >I've seen mention > X11/KDE, which would also involve threading. On
> >the other hand, it > could just be load. Tomorrow I'll load up a
> >box with non-threaded > apps and see what happens.
> > 
> > I'm suspecting bad combination between threaded apps and current
> > native preemption, either the preemption itself, or threads.
> > Running current kernel without any threaded apps turns up nothing
> > suspicious. Once the threaded apps started, it's like sending the
> > entire system to the death row.
> > 
> > I'm reverting following files to pre-July 2 to achive solid
> > stability:
> > 
> >  sys/sys/interrupt.h          - v1.27
> >  sys/kern/kern_intr.c         - v1.110
> >  sys/i386/i386/intr_machdep.c - v1.6
> >  sys/kern/sched_ule.c         - v1.109
> 
> Note that I haven't run across any issues after just reverting 
> sys/kern/sched_ule.c to rev. 1.113.  The same workload
> (X11/KDE/etc.) that crashes native preemption quite quickly has been
> running solidly for over 14 hours now.
>

rev. 1.113 causing annoying latency issue (as stated in the commit
log). Buildworld + xmms just ain't fun anymore.

I think the main culprit is within ithread_schedule() itself, as it
common to both ULE/4BSD.

--

Ariff Abdullah
MyBSD

http://www.MyBSD.org.my (IPv6/IPv4)
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