Messages in this thread Patch in this message | | | Subject | [PATCH] Create cpu_sibling_map for PPC64 | From | Matthew Dobson <> | Date | Wed, 28 Jul 2004 14:19:15 -0700 |
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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...
[mcd@arrakis source]$ diffstat ~/linux/patches/ppc64-cpu_sibling_map.patch arch/ppc64/kernel/smp.c | 7 +++++++ include/asm-ppc64/smp.h | 1 + 2 files changed, 8 insertions(+)
Signed-off-by: Matthew Dobson <colpatch@us.ibm.com>
-Matt
diff -Nurp --exclude-from=/home/mcd/.dontdiff linux-2.6.8-rc2-mm1/arch/ppc64/kernel/smp.c linux-2.6.8-rc2-mm1+ppc64-cpu_sibling_map/arch/ppc64/kernel/smp.c --- linux-2.6.8-rc2-mm1/arch/ppc64/kernel/smp.c 2004-07-28 10:50:29.000000000 -0700 +++ linux-2.6.8-rc2-mm1+ppc64-cpu_sibling_map/arch/ppc64/kernel/smp.c 2004-07-28 12:02:38.000000000 -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); @@ -870,6 +871,12 @@ 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 -Nurp --exclude-from=/home/mcd/.dontdiff linux-2.6.8-rc2-mm1/include/asm-ppc64/smp.h linux-2.6.8-rc2-mm1+ppc64-cpu_sibling_map/include/asm-ppc64/smp.h --- linux-2.6.8-rc2-mm1/include/asm-ppc64/smp.h 2004-07-28 10:50:50.000000000 -0700 +++ linux-2.6.8-rc2-mm1+ppc64-cpu_sibling_map/include/asm-ppc64/smp.h 2004-07-28 12:02:38.000000000 -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)
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