From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v5 6/9] KVM: MMU: introduce pte_prefetch_topup_memory_cache() Date: Sun, 11 Jul 2010 16:05:47 +0300 Message-ID: <4C39C1AB.6000606@redhat.com> References: <4C330918.6040709@cn.fujitsu.com> <4C330A37.8080709@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM list To: Xiao Guangrong Return-path: Received: from mx1.redhat.com ([209.132.183.28]:42721 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752452Ab0GKNFu (ORCPT ); Sun, 11 Jul 2010 09:05:50 -0400 In-Reply-To: <4C330A37.8080709@cn.fujitsu.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/06/2010 01:49 PM, Xiao Guangrong wrote: > Introduce this function to topup prefetch cache > > > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 3dcd55d..cda4587 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -89,6 +89,8 @@ module_param(oos_shadow, bool, 0644); > } > #endif > > +#define PTE_PREFETCH_NUM 16 > Let's make it 8 to start with... It's frightening enough. (8 = one cache line in both guest and host) > @@ -316,15 +318,16 @@ static void update_spte(u64 *sptep, u64 new_spte) > } > } > > -static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, > - struct kmem_cache *base_cache, int min) > +static int __mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, > + struct kmem_cache *base_cache, int min, > + int max, gfp_t flags) > { > void *obj; > > if (cache->nobjs>= min) > return 0; > - while (cache->nobjs< ARRAY_SIZE(cache->objects)) { > - obj = kmem_cache_zalloc(base_cache, GFP_KERNEL); > + while (cache->nobjs< max) { > + obj = kmem_cache_zalloc(base_cache, flags); > if (!obj) > return -ENOMEM; > cache->objects[cache->nobjs++] = obj; > @@ -332,6 +335,20 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, > return 0; > } > > +static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, > + struct kmem_cache *base_cache, int min) > +{ > + return __mmu_topup_memory_cache(cache, base_cache, min, > + ARRAY_SIZE(cache->objects), GFP_KERNEL); > +} > + > +static int pte_prefetch_topup_memory_cache(struct kvm_vcpu *vcpu) > +{ > + return __mmu_topup_memory_cache(&vcpu->arch.mmu_rmap_desc_cache, > + rmap_desc_cache, PTE_PREFETCH_NUM, > + PTE_PREFETCH_NUM, GFP_ATOMIC); > +} > + > Just make the ordinary topup sufficient for prefetch. If we allocate too much, we don't lose anything, the memory remains for the next time around. Note for shadow pages or pte chains you don't need extra pages, since the prefetch fits in just one shadow page. You only need extra for rmap. -- error compiling committee.c: too many arguments to function