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powerpc/mm: Optimize detection of thread local mm's

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Instead of comparing the whole CPU mask every time, let's
keep a counter of how many bits are set in the mask. Thus
testing for a local mm only requires testing if that counter
is 1 and the current CPU bit is set in the mask.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Benjamin Herrenschmidt 2017-07-24 14:28:02 +10:00 committed by Michael Ellerman
parent b426e4bd77
commit a619e59c07
4 changed files with 24 additions and 1 deletions
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3
arch/powerpc/include/asm/book3s/64/mmu.h
View File

@ -83,6 +83,9 @@ typedef struct {
mm_context_id_t id;
u16 user_psize; /* page size index */
/* Number of bits in the mm_cpumask */
atomic_t active_cpus;
/* NPU NMMU context */
struct npu_context *npu_context;

9
arch/powerpc/include/asm/mmu_context.h
View File

@ -96,6 +96,14 @@ static inline void switch_mm_pgdir(struct task_struct *tsk,
struct mm_struct *mm) { }
#endif
#ifdef CONFIG_PPC_BOOK3S_64
static inline void inc_mm_active_cpus(struct mm_struct *mm)
{
atomic_inc(&mm->context.active_cpus);
}
#else
static inline void inc_mm_active_cpus(struct mm_struct *mm) { }
#endif
/*
* switch_mm is the entry point called from the architecture independent
@ -110,6 +118,7 @@ static inline void switch_mm_irqs_off(struct mm_struct *prev,
/* Mark this context has been used on the new CPU */
if (!cpumask_test_cpu(smp_processor_id(), mm_cpumask(next))) {
cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
inc_mm_active_cpus(next);
/*
* This full barrier orders the store to the cpumask above vs

11
arch/powerpc/include/asm/tlb.h
View File

@ -69,13 +69,22 @@ static inline int mm_is_core_local(struct mm_struct *mm)
topology_sibling_cpumask(smp_processor_id()));
}
#ifdef CONFIG_PPC_BOOK3S_64
static inline int mm_is_thread_local(struct mm_struct *mm)
{
if (atomic_read(&mm->context.active_cpus) > 1)
return false;
return cpumask_test_cpu(smp_processor_id(), mm_cpumask(mm));
}
#else /* CONFIG_PPC_BOOK3S_64 */
static inline int mm_is_thread_local(struct mm_struct *mm)
{
return cpumask_equal(mm_cpumask(mm),
cpumask_of(smp_processor_id()));
}
#endif /* !CONFIG_PPC_BOOK3S_64 */
#else
#else /* CONFIG_SMP */
static inline int mm_is_core_local(struct mm_struct *mm)
{
return 1;

2
arch/powerpc/mm/mmu_context_book3s64.c
View File

@ -170,6 +170,8 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
#ifdef CONFIG_SPAPR_TCE_IOMMU
mm_iommu_init(mm);
#endif
atomic_set(&mm->context.active_cpus, 0);
return 0;
}