Message ID | 20200206030900.147032-12-leonardo@linux.ibm.com (mailing list archive) |
---|---|
State | Superseded, archived |
Headers | show |
Series | Introduces new functions for tracking lockless pagetable walks | expand |
Context | Check | Description |
---|---|---|
snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (530a1cfd52af0aba1af4b1c9a7bc66a202a459b1) |
snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
snowpatch_ozlabs/build-pmac32 | fail | build failed! |
snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 23 lines checked |
snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c index bb138b628f86..4822ff1aac4b 100644 --- a/arch/powerpc/mm/book3s64/pgtable.c +++ b/arch/powerpc/mm/book3s64/pgtable.c @@ -96,8 +96,22 @@ static DEFINE_PER_CPU(int, lockless_pgtbl_walk_counter); */ void serialize_against_pte_lookup(struct mm_struct *mm) { + int cpu; + struct cpumask cm; + smp_mb(); - smp_call_function_many(mm_cpumask(mm), do_nothing, NULL, 1); + + /* + * Fills a new cpumask only with cpus that are currently doing a + * lockless pagetable walk. This reduces time spent in this function. + */ + cpumask_clear(&cm); + for_each_cpu(cpu, mm_cpumask((mm))) { + if (per_cpu(lockless_pgtbl_walk_counter, cpu) > 0) + cpumask_set_cpu(cpu, &cm); + } + + smp_call_function_many(&cm, do_nothing, NULL, 1); } /* begin_lockless_pgtbl_walk: Must be inserted before a function call that does
For each cpu in cpumask, checks if it's running a lockless pagetable walk. Then, run serialize_against_pte_lookup() only on these cpus. serialize_agains_pte_lookup() can take a long while when there are a lot of cpus in cpumask. This method is intended to reduce this waiting, while not impacting too much on the lockless pagetable walk. Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> --- arch/powerpc/mm/book3s64/pgtable.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)