Re: Linux v2.6.12-rc6

From: Bill Davidsen
Date: Fri Jun 17 2005 - 12:47:24 EST

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
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@xxxxxxx)
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me
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