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Commit 5853aef1 authored by Michael Ellerman's avatar Michael Ellerman Committed by Benjamin Herrenschmidt
Browse files

powerpc: Add threads_per_subcore 



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: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarMichael Neuling <mikey@neuling.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 8d6f7c5a

arch/powerpc/include/asm/cputhreads.h

+7 −0
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/kernel/setup-common.c

+3 −1
Original line number Diff line number Diff line
@@ -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