[Cbe-oss-dev] CONFIG_SCHED_SMT

[Geoff Levand]

Benjamin Herrenschmidt wrote:
> On Tue, 2007-08-14 at 23:01 +0900, Hiroyuki Machida wrote:
>> Hi Ben,
>> 
>> Thank you for explanation. I think cpu_sibling_map[] will be initialized
>> according to cpu_spec. It's not platform specific, but common for PPC64.
>> In case of Cell, SMT flag is set and sibling map is expected to set correctly
>> in all Cell platform.  So it's better PS3 deconfig follows Cell defconfig.
> 
> That code:
> 
> 	for_each_possible_cpu(cpu) {
> 		cpu_set(cpu, cpu_sibling_map[cpu]);
> 		if (cpu_has_feature(CPU_FTR_SMT))
> 			cpu_set(cpu ^ 0x1, cpu_sibling_map[cpu]);
> 	}
> 
> Is a hack and will be going a way when some of the work I'm currently
> doing gets merged. The new code will rely on the
> 
> ibm,ppc-interrupt-server#s
> 
> property in the CPU mode. You need to make sure you get one of these
> that represents your two threads.

Yes, we already have that, as it is the only way for the current powerpc
startup code to recognize that a processor has multiple threads.

-Geoff