Hi, On Sun, Sep 06, 2020 at 01:43:21PM +0200, mateusznos...@gmail.com wrote: > From: Mateusz Nosek <mateusznos...@gmail.com> > > Most fields in struct pointed by 'subscriptions' are initialized explicitly > after the allocation. By changing kzalloc to kmalloc the call to memset > is avoided. As the only new code consists of 2 simple memory accesses, > the performance is increased.
Is there a measurable performance increase? The __mmu_notifier_register() is not used that frequently to trade off robustness of kzalloc() for slight (if visible at all) performance gain. > Signed-off-by: Mateusz Nosek <mateusznos...@gmail.com> > --- > mm/mmu_notifier.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index 4fc918163dd3..190e198dc5be 100644 > --- a/mm/mmu_notifier.c > +++ b/mm/mmu_notifier.c > @@ -625,7 +625,7 @@ int __mmu_notifier_register(struct mmu_notifier > *subscription, > * know that mm->notifier_subscriptions can't change while we > * hold the write side of the mmap_lock. > */ > - subscriptions = kzalloc( > + subscriptions = kmalloc( > sizeof(struct mmu_notifier_subscriptions), GFP_KERNEL); > if (!subscriptions) > return -ENOMEM; > @@ -636,6 +636,8 @@ int __mmu_notifier_register(struct mmu_notifier > *subscription, > subscriptions->itree = RB_ROOT_CACHED; > init_waitqueue_head(&subscriptions->wq); > INIT_HLIST_HEAD(&subscriptions->deferred_list); > + subscriptions->active_invalidate_ranges = 0; > + subscriptions->has_itree = false; > } > > ret = mm_take_all_locks(mm); > -- > 2.20.1 > > -- Sincerely yours, Mike.
