Hi Ben,
Le 24/07/2017 à 06:28, Benjamin Herrenschmidt a écrit :
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.
I'm trying to see if we could merge this patch with what I'm trying to
do to mark a context as requiring global TLBIs.
In http://patchwork.ozlabs.org/patch/796775/
I'm introducing a 'flags' per memory context, using one bit to say if
the context needs global TLBIs.
The 2 could co-exist, just checking... Do you think about using the
actual active_cpus count down the road, or is it just a matter of
knowing if there are more than one active cpus?
Thanks,
Fred
Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
---
arch/powerpc/include/asm/book3s/64/mmu.h | 3 +++
arch/powerpc/include/asm/mmu_context.h | 9 +++++++++
arch/powerpc/include/asm/tlb.h | 11 ++++++++++-
arch/powerpc/mm/mmu_context_book3s64.c | 2 ++
4 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h
b/arch/powerpc/include/asm/book3s/64/mmu.h
index 1a220cdff923..c3b00e8ff791 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu.h
@@ -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;
diff --git a/arch/powerpc/include/asm/mmu_context.h
b/arch/powerpc/include/asm/mmu_context.h
index ff1aeb2cd19f..cf8f50cd4030 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -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);
smp_mb();
new_on_cpu = true;
}
diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/asm/tlb.h
index 609557569f65..a7eabff27a0f 100644
--- a/arch/powerpc/include/asm/tlb.h
+++ b/arch/powerpc/include/asm/tlb.h
@@ -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;
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c
b/arch/powerpc/mm/mmu_context_book3s64.c
index 8159f5219137..de17d3e714aa 100644
--- a/arch/powerpc/mm/mmu_context_book3s64.c
+++ b/arch/powerpc/mm/mmu_context_book3s64.c
@@ -174,6 +174,8 @@ 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;
}
