cvs commit: src/sys/kern sched_ule.c (fwd)
Jeff Roberson
jroberson at chesapeake.net
Wed Jul 18 20:32:29 UTC 2007
On Wed, 18 Jul 2007, Max Laier wrote:
> On Wednesday 18 July 2007, Jeff Roberson wrote:
>> Thanks everyone for your help. In summary it sounds like there are two
>> issues.
>>
>> 1) kqemu explicitly uses sched_lock. I'll see if I can contact the
>> author about fixing this.
>>
>> 2) As much as a 6-7% slowdown on buildworld on dual core machines as
>> compared to 4BSD. I'm not sure if I'm going to do anything about this.
>> Once you get to 4 or 8 cores and -j8 or more they even out with ULE
>> having significantly less system time. I don't know if I want to
>> compromise that for slightly better dual core compile times.
>
> 3) nice(1) trouble?
>
> I wrote a quick script to fork off a couple of "yes > /dev/null" to stress
> test and it works really really fine. However, if I nice down the script
> it panics with
>
> | spin lock 0xffffffff806e5380 (sched lock 2) held by 0xffffff0001227000
> | (tid 100000) too long
> | panic: spin lock held too long
>
> This is almost 100% repeatable after 30-60 seconds, even with only 4 yes
> instances (where 4 is the # of CPUs).
Hey Max,
Thanks for the bug report. I'm not able to reproduce this myself. Can
you enable some debugging and get me a stack trace?
Thanks,
Jeff
>
>> This is in the tree for 7.0 now though. I'm very excited to see this
>> happen.
>>
>> Thanks again,
>> Jeff
>>
>> ---------- Forwarded message ----------
>> Date: Tue, 17 Jul 2007 22:53:24 +0000 (UTC)
>> From: Jeff Roberson <jeff at FreeBSD.org>
>> To: src-committers at FreeBSD.org, cvs-src at FreeBSD.org,
>> cvs-all at FreeBSD.org Subject: cvs commit: src/sys/kern sched_ule.c
>>
>> jeff 2007-07-17 22:53:24 UTC
>>
>> FreeBSD src repository
>>
>> Modified files:
>> sys/kern sched_ule.c
>> Log:
>> ULE 3.0: Fine grain scheduler locking and affinity improvements.
>> This has been in development for over 6 months as SCHED_SMP.
>> - Implement one spin lock per thread-queue. Threads assigned to a
>> run-queue point to this lock via td_lock.
>> - Improve the facility for assigning threads to CPUs now that
>> sched_lock contention no longer dominates scheduling decisions on
>> larger SMP machines.
>> - Re-write idle time stealing in an attempt to make it less
>> damaging to general performance. This is still disabled by default.
>> See kern.sched.steal_idle.
>> - Call the long-term load balancer from a callout rather than
>> sched_clock() so there are no locks held. This is disabled by default.
>> See kern.sched.balance.
>> - Parameterize many scheduling decisions via sysctls. Try to
>> document these via sysctl descriptions.
>> - General structural and naming cleanups.
>> - Document each function with comments.
>>
>> Tested by: current@ amd64, x86, UP, SMP.
>> Approved by: re
>>
>> Revision Changes Path
>> 1.200 +917 -549 src/sys/kern/sched_ule.c
>> _______________________________________________
>> freebsd-current at freebsd.org mailing list
>> http://lists.freebsd.org/mailman/listinfo/freebsd-current
>> To unsubscribe, send any mail to
>> "freebsd-current-unsubscribe at freebsd.org"
>
>
>
> --
> /"\ Best regards, | mlaier at freebsd.org
> \ / Max Laier | ICQ #67774661
> X http://pf4freebsd.love2party.net/ | mlaier at EFnet
> / \ ASCII Ribbon Campaign | Against HTML Mail and News
>
More information about the freebsd-current
mailing list