From: Matthew Dobson <colpatch@us.ibm.com>
In light of some proposed changes in the sched_domains code, I coded up
this little ditty that simply creates and populates a cpu_sibling_map for
PPC64 machines. The patch just checks the CPU flags to determine if the
CPU supports SMT (aka Hyper-Threading aka Multi-Threading aka ...) and
fills in a mask of the siblings for each CPU in the system. This should
allow us to build sched_domains for PPC64 with generic code in
kernel/sched.c for the SMT systems. SMT is becoming more popular and is
turning up in more and more architectures. I don't think it will be too
long until this feature is supported by most arches...
Signed-off-by: Matthew Dobson <colpatch@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/arch/ppc64/kernel/smp.c | 7 +++++++
25-akpm/include/asm-ppc64/smp.h | 1 +
2 files changed, 8 insertions(+)
diff -puN arch/ppc64/kernel/smp.c~create-cpu_sibling_map-for-ppc64 arch/ppc64/kernel/smp.c
--- 25/arch/ppc64/kernel/smp.c~create-cpu_sibling_map-for-ppc64 2004-08-01 23:00:35.878078640 -0700
+++ 25-akpm/arch/ppc64/kernel/smp.c 2004-08-01 23:00:35.884077728 -0700
@@ -64,6 +64,7 @@ cpumask_t cpu_possible_map = CPU_MASK_NO
cpumask_t cpu_online_map = CPU_MASK_NONE;
cpumask_t cpu_available_map = CPU_MASK_NONE;
cpumask_t cpu_present_at_boot = CPU_MASK_NONE;
+cpumask_t cpu_sibling_map[NR_CPUS] = { [0 .. NR_CPUS-1] = CPU_MASK_NONE };
EXPORT_SYMBOL(cpu_online_map);
EXPORT_SYMBOL(cpu_possible_map);
@@ -868,6 +869,12 @@ void __init smp_prepare_cpus(unsigned in
for_each_cpu(cpu)
if (cpu != boot_cpuid)
smp_create_idle(cpu);
+
+ for_each_cpu(cpu) {
+ cpu_set(cpu, cpu_sibling_map[cpu]);
+ if (cur_cpu_spec->cpu_features & CPU_FTR_SMT)
+ cpu_set(cpu ^ 0x1, cpu_sibling_map[cpu]);
+ }
}
void __devinit smp_prepare_boot_cpu(void)
diff -puN include/asm-ppc64/smp.h~create-cpu_sibling_map-for-ppc64 include/asm-ppc64/smp.h
--- 25/include/asm-ppc64/smp.h~create-cpu_sibling_map-for-ppc64 2004-08-01 23:00:35.879078488 -0700
+++ 25-akpm/include/asm-ppc64/smp.h 2004-08-01 23:00:35.885077576 -0700
@@ -49,6 +49,7 @@ extern cpumask_t cpu_present_at_boot;
extern cpumask_t cpu_online_map;
extern cpumask_t cpu_possible_map;
extern cpumask_t cpu_available_map;
+extern cpumask_t cpu_sibling_map[NR_CPUS];
#define cpu_present_at_boot(cpu) cpu_isset(cpu, cpu_present_at_boot)
#define cpu_available(cpu) cpu_isset(cpu, cpu_available_map)
_