From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
On POWER8 we have a new concept of a subcore. This is what happens when
you take a regular core and split it. A subcore is a grouping of two or
four SMT threads, as well as a handfull of SPRs which allows the subcore
to appear as if it were a core from the point of view of a guest.
Unlike threads_per_core which is fixed at boot, threads_per_subcore can
change while the system is running. Most code will not want to use
threads_per_subcore.
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Michael Neuling <mikey@xxxxxxxxxxx>
---
arch/powerpc/include/asm/cputhreads.h | 7 +++++++
arch/powerpc/kernel/setup-common.c | 4 +++-
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/cputhreads.h b/arch/powerpc/include/asm/cputhreads.h
index ac3eedb..2bf8e93 100644
--- a/arch/powerpc/include/asm/cputhreads.h
+++ b/arch/powerpc/include/asm/cputhreads.h
@@ -18,10 +18,12 @@
#ifdef CONFIG_SMP
extern int threads_per_core;
+extern int threads_per_subcore;
extern int threads_shift;
extern cpumask_t threads_core_mask;
#else
#define threads_per_core 1
+#define threads_per_subcore 1
#define threads_shift 0
#define threads_core_mask (CPU_MASK_CPU0)
#endif
@@ -74,6 +76,11 @@ static inline int cpu_thread_in_core(int cpu)
return cpu & (threads_per_core - 1);
}
+static inline int cpu_thread_in_subcore(int cpu)
+{
+ return cpu & (threads_per_subcore - 1);
+}
+
static inline int cpu_first_thread_sibling(int cpu)
{
return cpu & ~(threads_per_core - 1);
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 3cf25c8..aa0f5ed 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -390,9 +390,10 @@ void __init check_for_initrd(void)
#ifdef CONFIG_SMP
-int threads_per_core, threads_shift;
+int threads_per_core, threads_per_subcore, threads_shift;
cpumask_t threads_core_mask;
EXPORT_SYMBOL_GPL(threads_per_core);
+EXPORT_SYMBOL_GPL(threads_per_subcore);
EXPORT_SYMBOL_GPL(threads_shift);
EXPORT_SYMBOL_GPL(threads_core_mask);
@@ -401,6 +402,7 @@ static void __init cpu_init_thread_core_maps(int tpc)
int i;
threads_per_core = tpc;
+ threads_per_subcore = tpc;
cpumask_clear(&threads_core_mask);
/* This implementation only supports power of 2 number of threads
--
1.9.1
--
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