serialize_against_pte_lookup() performs IPIs to all CPUs in mm_cpumask.
Take this opportunity to try trim the CPU out of mm_cpumask. This can
reduce the cost of future serialize_against_pte_lookup() and/or the
cost of future TLB flushes.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/mm/book3s64/pgtable.c | 13 ++++++++++---
arch/powerpc/mm/book3s64/radix_tlb.c | 20 +++++++++++++-------
2 files changed, 23 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/mm/book3s64/pgtable.c
b/arch/powerpc/mm/book3s64/pgtable.c
index e18ae50a275c..ec23faf102b2 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -79,10 +79,17 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
}
-static void do_nothing(void *unused)
-{
+void exit_lazy_flush_tlb(struct mm_struct *mm, bool always_flush);
+static void do_serialize(void *arg)
+{
+ /* We've taken the IPI, so try to trim the mask while here */
+ if (radix_enabled()) {
+ struct mm_struct *mm = arg;
+ exit_lazy_flush_tlb(mm, false);
+ }
}
+
/*
* Serialize against find_current_mm_pte which does lock-less
* lookup in page tables with local interrupts disabled. For huge pages
@@ -96,7 +103,7 @@ static void do_nothing(void *unused)
void serialize_against_pte_lookup(struct mm_struct *mm)
{
smp_mb();
- smp_call_function_many(mm_cpumask(mm), do_nothing, NULL, 1);
+ smp_call_function_many(mm_cpumask(mm), do_serialize, mm, 1);
}
/*
diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c
b/arch/powerpc/mm/book3s64/radix_tlb.c
index 4dca7cbf07e9..d04c80d6f52c 100644
--- a/arch/powerpc/mm/book3s64/radix_tlb.c
+++ b/arch/powerpc/mm/book3s64/radix_tlb.c
@@ -630,7 +630,11 @@ static bool mm_needs_flush_escalation(struct mm_struct *mm)
return false;
}
-static void exit_lazy_flush_tlb(struct mm_struct *mm)
+/*
+ * If always_flush is true, then flush even if this CPU can't be removed
+ * from mm_cpumask.
+ */
+void exit_lazy_flush_tlb(struct mm_struct *mm, bool always_flush)
{
unsigned long pid = mm->context.id;
int cpu = smp_processor_id();
@@ -643,7 +647,7 @@ static void exit_lazy_flush_tlb(struct mm_struct *mm)
* done with interrupts off.
*/
if (current->mm == mm)
- goto out_flush;
+ goto out;
if (current->active_mm == mm) {
WARN_ON_ONCE(current->mm != NULL);
@@ -665,17 +669,19 @@ static void exit_lazy_flush_tlb(struct mm_struct *mm)
if (cpumask_test_cpu(cpu, mm_cpumask(mm))) {
atomic_dec(&mm->context.active_cpus);
cpumask_clear_cpu(cpu, mm_cpumask(mm));
+ always_flush = true;
}
-out_flush:
- _tlbiel_pid(pid, RIC_FLUSH_ALL);
+out:
+ if (always_flush)
+ _tlbiel_pid(pid, RIC_FLUSH_ALL);
}
#ifdef CONFIG_SMP
static void do_exit_flush_lazy_tlb(void *arg)
{
struct mm_struct *mm = arg;
- exit_lazy_flush_tlb(mm);
+ exit_lazy_flush_tlb(mm, true);
}
static void exit_flush_lazy_tlbs(struct mm_struct *mm)
@@ -737,7 +743,7 @@ static enum tlb_flush_type flush_type_needed(struct
mm_struct *mm, bool fullmm)
* to trim.
*/
if (tick_and_test_trim_clock()) {
- exit_lazy_flush_tlb(mm);
+ exit_lazy_flush_tlb(mm, true);
return FLUSH_TYPE_NONE;
}
}
@@ -783,7 +789,7 @@ static enum tlb_flush_type flush_type_needed(struct
mm_struct *mm, bool fullmm)
if (current->mm == mm)
return FLUSH_TYPE_LOCAL;
if (cpumask_test_cpu(cpu, mm_cpumask(mm)))
- exit_lazy_flush_tlb(mm);
+ exit_lazy_flush_tlb(mm, true);
return FLUSH_TYPE_NONE;
}
--
2.23.0
