[RFC,4/9] create aggregate kvm_total_used_mmu_pages value

Commit Message

David Hansen June 15, 2010, 1:55 p.m. UTC

None

Patch

diff -puN arch/x86/kvm/mmu.c~make_global_used_value arch/x86/kvm/mmu.c
--- linux-2.6.git/arch/x86/kvm/mmu.c~make_global_used_value	2010-06-09 15:14:30.000000000 -0700
+++ linux-2.6.git-dave/arch/x86/kvm/mmu.c	2010-06-09 15:14:30.000000000 -0700
@@ -891,6 +891,19 @@  static int is_empty_shadow_page(u64 *spt
 }
 #endif
 
+/*
+ * This value is the sum of all of the kvm instances's
+ * kvm->arch.n_used_mmu_pages values.  We need a global,
+ * aggregate version in order to make the slab shrinker
+ * faster
+ */
+static unsigned int kvm_total_used_mmu_pages;
+static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr)
+{
+	kvm->arch.n_used_mmu_pages += nr;
+	kvm_total_used_mmu_pages += nr;
+}
+
 static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
 	ASSERT(is_empty_shadow_page(sp->spt));
@@ -898,7 +911,7 @@  static void kvm_mmu_free_page(struct kvm
 	__free_page(virt_to_page(sp->spt));
 	__free_page(virt_to_page(sp->gfns));
 	kfree(sp);
-	--kvm->arch.n_used_mmu_pages;
+	kvm_mod_used_mmu_pages(kvm, -1);
 }
 
 static unsigned kvm_page_table_hashfn(gfn_t gfn)
@@ -919,7 +932,7 @@  static struct kvm_mmu_page *kvm_mmu_allo
 	bitmap_zero(sp->slot_bitmap, KVM_MEMORY_SLOTS + KVM_PRIVATE_MEM_SLOTS);
 	sp->multimapped = 0;
 	sp->parent_pte = parent_pte;
-	++vcpu->kvm->arch.n_used_mmu_pages;
+	kvm_mod_used_mmu_pages(vcpu->kvm, +1);
 	return sp;
 }
 
@@ -2914,21 +2927,20 @@  static int mmu_shrink(int nr_to_scan, gf
 {
 	struct kvm *kvm;
 	struct kvm *kvm_freed = NULL;
-	int cache_count = 0;
+
+	if (nr_to_scan == 0)
+		goto out;
 
 	spin_lock(&kvm_lock);
 
 	list_for_each_entry(kvm, &vm_list, vm_list) {
-		int npages, idx, freed_pages;
+		int idx, freed_pages;
 
 		idx = srcu_read_lock(&kvm->srcu);
 		spin_lock(&kvm->mmu_lock);
-		npages = kvm->arch.n_max_mmu_pages -
-			 kvm_mmu_available_pages(kvm);
-		cache_count += npages;
-		if (!kvm_freed && nr_to_scan > 0 && npages > 0) {
+		if (!kvm_freed && nr_to_scan > 0 &&
+		    kvm->arch.n_used_mmu_pages > 0) {
 			freed_pages = kvm_mmu_remove_some_alloc_mmu_pages(kvm);
-			cache_count -= freed_pages;
 			kvm_freed = kvm;
 		}
 		nr_to_scan--;
@@ -2941,7 +2953,8 @@  static int mmu_shrink(int nr_to_scan, gf
 
 	spin_unlock(&kvm_lock);
 
-	return cache_count;
+out:
+	return kvm_total_used_mmu_pages;
 }
 
 static struct shrinker mmu_shrinker = {