From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id CDDA190015D for ; Wed, 22 Jun 2011 02:16:00 -0400 (EDT) Received: by mail-wy0-f171.google.com with SMTP id 11so341707wyi.30 for ; Tue, 21 Jun 2011 23:15:59 -0700 (PDT) Message-ID: <4E018897.7040707@ravellosystems.com> Date: Wed, 22 Jun 2011 09:15:51 +0300 From: Izik Eidus MIME-Version: 1.0 Subject: Re: [PATCH] mmu_notifier, kvm: Introduce dirty bit tracking in spte and mmu notifier to help KSM dirty bit tracking References: <201106212055.25400.nai.xia@gmail.com> <201106212132.39311.nai.xia@gmail.com> <20110622002123.GP25383@sequoia.sous-sol.org> In-Reply-To: <20110622002123.GP25383@sequoia.sous-sol.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Chris Wright Cc: Nai Xia , Andrew Morton , Andrea Arcangeli , Hugh Dickins , Rik van Riel , linux-mm , Johannes Weiner , linux-kernel , kvm , mtosatti@redhat.com On 6/22/2011 3:21 AM, Chris Wright wrote: > * Nai Xia (nai.xia@gmail.com) wrote: >> Introduced kvm_mmu_notifier_test_and_clear_dirty(), kvm_mmu_notifier_dirty_update() >> and their mmu_notifier interfaces to support KSM dirty bit tracking, which brings >> significant performance gain in volatile pages scanning in KSM. >> Currently, kvm_mmu_notifier_dirty_update() returns 0 if and only if intel EPT is >> enabled to indicate that the dirty bits of underlying sptes are not updated by >> hardware. > Did you test with each of EPT, NPT and shadow? > >> Signed-off-by: Nai Xia >> Acked-by: Izik Eidus >> --- >> arch/x86/include/asm/kvm_host.h | 1 + >> arch/x86/kvm/mmu.c | 36 +++++++++++++++++++++++++++++ >> arch/x86/kvm/mmu.h | 3 +- >> arch/x86/kvm/vmx.c | 1 + >> include/linux/kvm_host.h | 2 +- >> include/linux/mmu_notifier.h | 48 +++++++++++++++++++++++++++++++++++++++ >> mm/mmu_notifier.c | 33 ++++++++++++++++++++++++++ >> virt/kvm/kvm_main.c | 27 ++++++++++++++++++++++ >> 8 files changed, 149 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> index d2ac8e2..f0d7aa0 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -848,6 +848,7 @@ extern bool kvm_rebooting; >> int kvm_unmap_hva(struct kvm *kvm, unsigned long hva); >> int kvm_age_hva(struct kvm *kvm, unsigned long hva); >> int kvm_test_age_hva(struct kvm *kvm, unsigned long hva); >> +int kvm_test_and_clear_dirty_hva(struct kvm *kvm, unsigned long hva); >> void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte); >> int cpuid_maxphyaddr(struct kvm_vcpu *vcpu); >> int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu); >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index aee3862..a5a0c51 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -979,6 +979,37 @@ out: >> return young; >> } >> >> +/* >> + * Caller is supposed to SetPageDirty(), it's not done inside this. >> + */ >> +static >> +int kvm_test_and_clear_dirty_rmapp(struct kvm *kvm, unsigned long *rmapp, >> + unsigned long data) >> +{ >> + u64 *spte; >> + int dirty = 0; >> + >> + if (!shadow_dirty_mask) { >> + WARN(1, "KVM: do NOT try to test dirty bit in EPT\n"); >> + goto out; >> + } > This should never fire with the dirty_update() notifier test, right? > And that means that this whole optimization is for the shadow mmu case, > arguably the legacy case. > Hi Chris, AMD npt does track the dirty bit in the nested page tables, so the shadow_dirty_mask should not be 0 in that case... -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org