KVM: sort memslots by its size and use line search
Sort memslots base on its size and use line search to find it, so that the
larger memslots have better fit
The idea is from Avi
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7b60849..6e8eb15 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -440,6 +440,15 @@
#endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
+static void kvm_init_memslots_id(struct kvm *kvm)
+{
+ int i;
+ struct kvm_memslots *slots = kvm->memslots;
+
+ for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
+ slots->memslots[i].id = i;
+}
+
static struct kvm *kvm_create_vm(void)
{
int r, i;
@@ -465,6 +474,7 @@
kvm->memslots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
if (!kvm->memslots)
goto out_err_nosrcu;
+ kvm_init_memslots_id(kvm);
if (init_srcu_struct(&kvm->srcu))
goto out_err_nosrcu;
for (i = 0; i < KVM_NR_BUSES; i++) {
@@ -630,15 +640,54 @@
}
#endif /* !CONFIG_S390 */
+static struct kvm_memory_slot *
+search_memslots(struct kvm_memslots *slots, gfn_t gfn)
+{
+ struct kvm_memory_slot *memslot;
+
+ kvm_for_each_memslot(memslot, slots)
+ if (gfn >= memslot->base_gfn &&
+ gfn < memslot->base_gfn + memslot->npages)
+ return memslot;
+
+ return NULL;
+}
+
+static int cmp_memslot(const void *slot1, const void *slot2)
+{
+ struct kvm_memory_slot *s1, *s2;
+
+ s1 = (struct kvm_memory_slot *)slot1;
+ s2 = (struct kvm_memory_slot *)slot2;
+
+ if (s1->npages < s2->npages)
+ return 1;
+ if (s1->npages > s2->npages)
+ return -1;
+
+ return 0;
+}
+
+/*
+ * Sort the memslots base on its size, so the larger slots
+ * will get better fit.
+ */
+static void sort_memslots(struct kvm_memslots *slots)
+{
+ sort(slots->memslots, KVM_MEM_SLOTS_NUM,
+ sizeof(struct kvm_memory_slot), cmp_memslot, NULL);
+}
+
void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new)
{
if (new) {
int id = new->id;
struct kvm_memory_slot *old = id_to_memslot(slots, id);
+ unsigned long npages = old->npages;
*old = *new;
- if (id >= slots->nmemslots)
- slots->nmemslots = id + 1;
+ if (new->npages != npages)
+ sort_memslots(slots);
}
slots->generation++;
@@ -980,14 +1029,7 @@
static struct kvm_memory_slot *__gfn_to_memslot(struct kvm_memslots *slots,
gfn_t gfn)
{
- struct kvm_memory_slot *memslot;
-
- kvm_for_each_memslot(memslot, slots)
- if (gfn >= memslot->base_gfn
- && gfn < memslot->base_gfn + memslot->npages)
- return memslot;
-
- return NULL;
+ return search_memslots(slots, gfn);
}
struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
@@ -998,20 +1040,13 @@
int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
{
- int i;
- struct kvm_memslots *slots = kvm_memslots(kvm);
+ struct kvm_memory_slot *memslot = gfn_to_memslot(kvm, gfn);
- for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
- struct kvm_memory_slot *memslot = &slots->memslots[i];
+ if (!memslot || memslot->id >= KVM_MEMORY_SLOTS ||
+ memslot->flags & KVM_MEMSLOT_INVALID)
+ return 0;
- if (memslot->flags & KVM_MEMSLOT_INVALID)
- continue;
-
- if (gfn >= memslot->base_gfn
- && gfn < memslot->base_gfn + memslot->npages)
- return 1;
- }
- return 0;
+ return 1;
}
EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);