Stability?
Scott Long
scottl at samsco.org
Tue Aug 3 09:44:57 PDT 2004
Evan Dower wrote:
> % uptime
> 9:23AM up 1 day, 15:42, 6 users, load averages: 0,98 1,19 1,25
>
> With a recent cvsup (and all the rebuilding and installing involved) I
> have noticed what seems to be an improvement in stability. I must have
> missed any postings about it. Any, recent cvsup means about an hour
> before this:
>
> % uname -a
> FreeBSD lojak.washington.edu 5.2-CURRENT FreeBSD 5.2-CURRENT #0: Sun
> Aug 1 16:06:05 PDT 2004
> root at lojak.washington.edu:/usr/obj/usr/src/sys/DEBUG i386
>
> I noticed that my kernel has now started saying (in the dmesg):
> WARNING: Kernel preemption is disabled, expect reduced performance.
>
I turned off normal preemption a few days ago in order to cover up
the stability problems until the responsible parties (including myself)
get them fixed. It is just a hack for now.
> Of course, I have WITNESS turned on in my debug kernel so I already
> expect reduced performance. Is this message suggesting that I put
> FULL_PREEMPTION in my kernel? I was under the impression that it was
> only useful for seeing where stuff broke. Is stuff so good now that it
> will improve performance without significant effect on stability? Or
> perhaps it is indicating that PREEMPTION is #undef'd? I didn't #undef it
> so if this is the case it must have been changed upstream.
You likely do not want to turn on FULL_PREEMPTION. If you want the
old behavior, edit /sys/i386/include/param.h and reenable the
PREEMPTION definition.
Scott
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