Date: Sat, 10 Jul 2004 02:12:39 -0500 From: Jon Noack <noackjr@alumni.rice.edu> To: Ariff Abdullah <skywizard@MyBSD.org.my> Cc: Robert Watson <rwatson@freebsd.org> Subject: Re: Native preemption is the culprit [was Re: today's CURRENT lockups] Message-ID: <40EF96E7.3090608@alumni.rice.edu> In-Reply-To: <20040710150620.7595b207.skywizard@MyBSD.org.my> References: <Pine.NEB.3.96L.1040709231313.19581G-100000@fledge.watson.org> <Pine.NEB.3.96L.1040710011206.19581H-100000@fledge.watson.org> <20040710150620.7595b207.skywizard@MyBSD.org.my>
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On 07/10/04 02:06, Ariff Abdullah wrote: > On Sat, 10 Jul 2004 01:18:06 -0400 (EDT) > Robert Watson <rwatson@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. Jon
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