Date: Fri, 9 Jul 2004 23:46:09 -0400 (EDT) From: Robert Watson <rwatson@freebsd.org> To: "Marc G. Fournier" <scrappy@hub.org> Cc: Steve Kargl <sgk@troutmask.apl.washington.edu> Subject: Re: Native preemption is the culprit [was Re: today's CURRENT lockups] Message-ID: <Pine.NEB.3.96L.1040709231313.19581G-100000@fledge.watson.org> In-Reply-To: <20040709144251.X728@ganymede.hub.org>
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On Fri, 9 Jul 2004, Marc G. Fournier wrote: > On Fri, 9 Jul 2004, Steve Kargl wrote: > > > I've tested it on a UP kernel (HTT enabled, ACPI disabled, > > APIC enabled, ULE). Appears to work fine. > > 'k, I just upgraded my machine to latest, running ULE, P4, SMP kernel > (but doesn't find or start up a second CPU) ... just locked solid here > too ... unfortunately, was running X at the time, so don't know if it > locked or panic'd to DDB :( Running non-X right now to see if it happens > again ... I'm now experiencing extremely hard hangs in the following configurations: SMP kernel running SCHED_ULE with hyperthreads SMP kernel running SCHED_4BSD with hyperthreads To generate the load, I'm using the "supersmack" benchark with the select-key.smack query set with 30 client workers and 10,000 transactions. I am able to reliable hang the system with one or two runs. By disabling the "#define PREEMPTION" entry in param.h with SCHED_4BSD, I'm able to complete the benchmark several times in a row without apparent problems. However, I'll leave it running for a few more hours and see if I didn't just "get lucky". I'll then try SCHED_ULE w/o PREEMPTION. By "extremely hard" I mean that I am unable to break into the debugger using a serial break on the serial console. I have not yet been able to run the test on a system with easily accessible NMI but will attempt to do so in the next few days. I'll give UP a spin with various combinations next. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Principal Research Scientist, McAfee Research
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