Re: FreeBSD unstable on Dell 1750 using SMP?

Dan Charrois <dan@xxxxxxx> · Wed, 30 Nov 2005 18:26:29 -0700

This is encouraging - it's the first I've heard of someone who has  
found a way to trigger the problem "on demand".  The problems I was  
experiencing were on a dual Xeon with HTT enabled as well.    Perhaps  
someone out there who knows much more about the inner workings of  
FreeBSD may have an idea of why running top in "aggressive mode" like  
this might trigger the random rebooting.  In particular, it would be  
nice to *know* that someone out there specifically fixed whatever is  
wrong in 5.4 when bringing it to 6.0.  It's encouraging that you  
haven't had any problems since upgrading to 6.0, but I have to wonder  
if the bug's actually fixed, or the specific trigger of running top  
doesn't trigger the problem but the problem is still lurking in the  
background waiting to strike with the right combination of events.
In any case, I'm anxious to try it out myself on our server to see if  
"top -s0" brings it down "on command" with HTT enabled, and not with  
HTT disabled.  But I'm going to have to wait until some time over the  
Christmas holidays to do that sort of experimentation at a time when  
it isn't affecting the end users of the machine.  I may also upgrade  
to 6.0 at that time, since by then it will have been out for a couple  
of months, so most of the worst quirks should be worked out by then.
In the meantime, disabling HTT as I've done seems like a reasonable  
precaution to improve the stability..
Thanks for your help!
Dan
On Nov 29, 2005, at 10:50 PM, Stephen Montgomery-Smith wrote:
Dan Charrois wrote:
It actually may be a comfort, since perhaps HTT is related to the   
culprit.  Since the last crash, about a month ago, I disabled  
HTT,  both in the kernel as well in the BIOS.  So as far as I  
know, it's  completely been disabled (and the boot messages and  
top only show 2  CPUs).  And I haven't had the system go down for  
nearly a month now.

I don't know if it is related, but I used to have random reboots on  
a dual Xeon system with HTT enabled.  It happened when I ran a CPU  
intensive threaded program at the same time as "top" - running "top  
-s0" (which you have to do as root) could usually kill the machine  
in seconds if not minutes.
All I can tell you is that with FreeBSD 6.0 the problem disappeared.
Well not totally - I still get a bunch of harmless calcru negative  
messages, although I don't know if it is actually related to the  
boot problems I used to have with FreeBSD 5.4, because I get the  
calcru backwards messages even with HTT disabled.
Anyway, if you are in the mood to try it out, you might like to try  
re-enabling HTT, starting up whatever process you usually use (I'm  
guessing it is MySQL), and then run "top -s0".  If you get a crash  
soon after that, you have the same problem I had.
Let me also add that these crashes usually did not trigger a crash  
dump (I had dumpon set), and when it did the resulting dump looked  
rather corrupted.
Stephen

--
Syzygy Research & Technology
Box 83, Legal, AB  T0G 1L0 Canada
Phone: 780-961-2213
_______________________________________________
freebsd-stable@xxxxxxxxxxx mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-stable
To unsubscribe, send any mail to "freebsd-stable-unsubscribe@xxxxxxxxxxx"

Re: FreeBSD unstable on Dell 1750 using SMP?

Relevant Pages