On a 64bits machine, struct is naturally aligned with 8 bytes. Since
kvm_mmu_page member *unsync* and *role* are less then 4 bytes, we can
rearrange the sequence to compace the struct.
As the comment shows, *role* and *gfn* are used to key the shadow page. In
order to keep the comment valid, this patch moves the *unsync* up and
exchange the position of *role* and *gfn*.
>From /proc/slabinfo, it shows the size of kvm_mmu_page is 8 bytes less and
with one more object per slap after applying this patch.
# name <active_objs> <num_objs> <objsize> <objperslab>
kvm_mmu_page_header 0 0 168 24
kvm_mmu_page_header 0 0 160 25
Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 00ddb0c9e612..f1a4e520ef5c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -280,18 +280,18 @@ struct kvm_rmap_head {
struct kvm_mmu_page {
struct list_head link;
struct hlist_node hash_link;
+ bool unsync;
/*
* The following two entries are used to key the shadow page in the
* hash table.
*/
- gfn_t gfn;
union kvm_mmu_page_role role;
+ gfn_t gfn;
u64 *spt;
/* hold the gfn of each spte inside spt */
gfn_t *gfns;
- bool unsync;
int root_count; /* Currently serving as active root */
unsigned int unsync_children;
struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */
--
2.15.1
