| Message ID | 20190131183706.20980-3-jglisse@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Restore change_pte optimization to its former glory | expand |
On Thu, Jan 31, 2019 at 01:37:04PM -0500, Jerome Glisse wrote: > From: Jérôme Glisse <jglisse@redhat.com> > > Use unsigned for event field in range struct so that we can also set > flags with the event. This patch change the field and introduce the > helper. > > Signed-off-by: Jérôme Glisse <jglisse@redhat.com> > Cc: Andrea Arcangeli <aarcange@redhat.com> > Cc: Peter Xu <peterx@redhat.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: kvm@vger.kernel.org > --- > include/linux/mmu_notifier.h | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h > index be873c431886..d7a35975c2bd 100644 > --- a/include/linux/mmu_notifier.h > +++ b/include/linux/mmu_notifier.h > @@ -6,6 +6,7 @@ > #include <linux/spinlock.h> > #include <linux/mm_types.h> > #include <linux/srcu.h> > +#include <linux/log2.h> > > struct mmu_notifier; > struct mmu_notifier_ops; > @@ -38,8 +39,11 @@ enum mmu_notifier_event { > MMU_NOTIFY_PROTECTION_VMA, > MMU_NOTIFY_PROTECTION_PAGE, > MMU_NOTIFY_SOFT_DIRTY, > + MMU_NOTIFY_EVENT_MAX > }; > > +#define MMU_NOTIFIER_EVENT_BITS order_base_2(MMU_NOTIFY_EVENT_MAX) > + > #ifdef CONFIG_MMU_NOTIFIER > > /* > @@ -60,7 +64,7 @@ struct mmu_notifier_range { > struct mm_struct *mm; > unsigned long start; > unsigned long end; > - enum mmu_notifier_event event; > + unsigned event; > bool blockable; > }; This is only allocated in the stack, so saving RAM by mixing bitfields with enum in the same 4 bytes to save 4 bytes isn't of maximum priority. A possibly cleaner way to save those 4 bytes without mixing enum with bitfields by hand, is to add a "unsigned short flags" which will make "event/flags/blockable" fit in the same 8 bytes (bool only needs 1 byte) as before the patch (the first bitfield can start from 0 then). Yet another way is to drop blockable and convert it to a flag in "unsigned int flags".
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h index be873c431886..d7a35975c2bd 100644 --- a/include/linux/mmu_notifier.h +++ b/include/linux/mmu_notifier.h @@ -6,6 +6,7 @@ #include <linux/spinlock.h> #include <linux/mm_types.h> #include <linux/srcu.h> +#include <linux/log2.h> struct mmu_notifier; struct mmu_notifier_ops; @@ -38,8 +39,11 @@ enum mmu_notifier_event { MMU_NOTIFY_PROTECTION_VMA, MMU_NOTIFY_PROTECTION_PAGE, MMU_NOTIFY_SOFT_DIRTY, + MMU_NOTIFY_EVENT_MAX }; +#define MMU_NOTIFIER_EVENT_BITS order_base_2(MMU_NOTIFY_EVENT_MAX) + #ifdef CONFIG_MMU_NOTIFIER /* @@ -60,7 +64,7 @@ struct mmu_notifier_range { struct mm_struct *mm; unsigned long start; unsigned long end; - enum mmu_notifier_event event; + unsigned event; bool blockable; }; @@ -352,7 +356,7 @@ static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) static inline void mmu_notifier_range_init(struct mmu_notifier_range *range, - enum mmu_notifier_event event, + unsigned event, struct vm_area_struct *vma, struct mm_struct *mm, unsigned long start,