Re: Linux v2.6.12-rc6

Bill Davidsen
2005-06-17T17:46:20Z

Johannes Stezenbach wrote:
> Brice Goglin wrote:
>
>>Johannes Stezenbach a écrit :
>>
>>>Johannes Stezenbach wrote:
>>>
>>>
>>>>Hype-threading stopped working for me (probably due to
>>>>me not enabling ACPI). dmesg output and .config attached.
>>>>-rc5 worked fine. The board is an Asus P4P800-Deluxe.
>>>>
>>>>dmesg: WARNING: 1 siblings found for CPU0, should be 2
>>>
>>>
>>>Indeed SMT works fine if I enable ACPI.
>>>Is SMT without ACPI not supported?
>>
>>You can pass acpi=ht into the kernel command line to disable
>>ACPI except the minimum required to get HT support.
>
>
> That's nice, but I was thinking along the lines of:
>
> diff -ur linux-2.6.12-rc6.orig/arch/i386/Kconfig linux-2.6.12-rc6/arch/i386/Kconfig
> --- linux-2.6.12-rc6.orig/arch/i386/Kconfig 2005-06-06 23:16:27.000000000 +0200
> +++ linux-2.6.12-rc6/arch/i386/Kconfig 2005-06-08 13:35:08.000000000 +0200
> @@ -503,7 +503,7 @@
>
> config SCHED_SMT
> bool "SMT (Hyperthreading) scheduler support"
> - depends on SMP
> + depends on SMP && ACPI
> default off
> help
> SMT scheduler support improves the CPU scheduler's decision making
>
> Comments? Is this intended?

I would think that you can't do HT without ACPI, so there's no point in
building in HT scheduling unless you can have HT.

Is that what you were asking? I was hoping someone else would comment.

Scheduling is getting harder and harder to get right... I have this
thought of a Beowolf cluster of NUMA machines, with each node being HT
multicore SMP. By "right" I meant "optimal," I'm sure that setup would
do something reasonable with current scheduling.

--
-bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me