From: Paolo Bonzini <pbonzini@redhat.com> To: "Michael S. Tsirkin" <mst@redhat.com> Cc: Peter Xu <peterx@redhat.com>, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Sean Christopherson <sean.j.christopherson@intel.com>, "Dr . David Alan Gilbert" <dgilbert@redhat.com>, Vitaly Kuznetsov <vkuznets@redhat.com> Subject: Re: [PATCH RFC 04/15] KVM: Implement ring-based dirty memory tracking Date: Thu, 12 Dec 2019 09:12:04 +0100 Message-ID: <74edef57-c1c7-53cb-4b93-291d9f816688@redhat.com> (raw) In-Reply-To: <20191212023154-mutt-send-email-mst@kernel.org> On 12/12/19 08:36, Michael S. Tsirkin wrote: > On Thu, Dec 12, 2019 at 01:08:14AM +0100, Paolo Bonzini wrote: >>>> I'd say it won't be a big issue on locking 1/2M of host mem for a >>>> vm... >>>> Also note that if dirty ring is enabled, I plan to evaporate the >>>> dirty_bitmap in the next post. The old kvm->dirty_bitmap takes >>>> $GUEST_MEM/32K*2 mem. E.g., for 64G guest it's 64G/32K*2=4M. If with >>>> dirty ring of 8 vcpus, that could be 64K*8=0.5M, which could be even >>>> less memory used. >>> >>> Right - I think Avi described the bitmap in kernel memory as one of >>> design mistakes. Why repeat that with the new design? >> >> Do you have a source for that? > > Nope, it was a private talk. > >> At least the dirty bitmap has to be >> accessed from atomic context so it seems unlikely that it can be moved >> to user memory. > > Why is that? We could surely do it from VCPU context? Spinlock is taken. >> The dirty ring could use user memory indeed, but it would be much harder >> to set up (multiple ioctls for each ring? what to do if userspace >> forgets one? etc.). > > Why multiple ioctls? If you do like virtio packed ring you just need the > base and the size. You have multiple rings, so multiple invocations of one ioctl. Paolo
next prev parent reply index Thread overview: 121+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-11-29 21:34 [PATCH RFC 00/15] KVM: Dirty ring interface Peter Xu 2019-11-29 21:34 ` [PATCH RFC 01/15] KVM: Move running VCPU from ARM to common code Peter Xu 2019-12-03 19:01 ` Sean Christopherson 2019-12-04 9:42 ` Paolo Bonzini 2019-12-09 22:05 ` Peter Xu 2019-11-29 21:34 ` [PATCH RFC 02/15] KVM: Add kvm/vcpu argument to mark_dirty_page_in_slot Peter Xu 2019-12-02 19:32 ` Sean Christopherson 2019-12-02 20:49 ` Peter Xu 2019-11-29 21:34 ` [PATCH RFC 03/15] KVM: Add build-time error check on kvm_run size Peter Xu 2019-12-02 19:30 ` Sean Christopherson 2019-12-02 20:53 ` Peter Xu 2019-12-02 22:19 ` Sean Christopherson 2019-12-02 22:40 ` Peter Xu 2019-12-03 5:50 ` Sean Christopherson 2019-12-03 13:41 ` Paolo Bonzini 2019-12-03 17:04 ` Peter Xu 2019-11-29 21:34 ` [PATCH RFC 04/15] KVM: Implement ring-based dirty memory tracking Peter Xu 2019-12-02 20:10 ` Sean Christopherson 2019-12-02 21:16 ` Peter Xu 2019-12-02 21:50 ` Sean Christopherson 2019-12-02 23:09 ` Peter Xu 2019-12-03 13:48 ` Paolo Bonzini 2019-12-03 18:46 ` Sean Christopherson 2019-12-04 10:05 ` Paolo Bonzini 2019-12-07 0:29 ` Sean Christopherson 2019-12-09 9:37 ` Paolo Bonzini 2019-12-09 21:54 ` Peter Xu 2019-12-10 10:07 ` Paolo Bonzini 2019-12-10 15:52 ` Peter Xu 2019-12-10 17:09 ` Paolo Bonzini 2019-12-15 17:21 ` Peter Xu 2019-12-16 10:08 ` Paolo Bonzini 2019-12-16 18:54 ` Peter Xu 2019-12-17 9:01 ` Paolo Bonzini 2019-12-17 16:24 ` Peter Xu 2019-12-17 16:28 ` Paolo Bonzini 2019-12-18 21:58 ` Peter Xu 2019-12-18 22:24 ` Sean Christopherson 2019-12-18 22:37 ` Paolo Bonzini 2019-12-18 22:49 ` Peter Xu 2019-12-17 2:28 ` Tian, Kevin 2019-12-17 16:18 ` Alex Williamson 2019-12-17 16:30 ` Paolo Bonzini 2019-12-18 0:29 ` Tian, Kevin [not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19D645E5F@SHSMSX104.ccr.corp.intel.com> 2019-12-17 5:17 ` Tian, Kevin 2019-12-17 5:25 ` Yan Zhao 2019-12-17 16:24 ` Alex Williamson 2019-12-03 19:13 ` Sean Christopherson 2019-12-04 10:14 ` Paolo Bonzini 2019-12-04 14:33 ` Sean Christopherson 2019-12-04 10:38 ` Jason Wang 2019-12-04 11:04 ` Paolo Bonzini 2019-12-04 19:52 ` Peter Xu 2019-12-05 6:51 ` Jason Wang 2019-12-05 12:08 ` Peter Xu 2019-12-05 13:12 ` Jason Wang 2019-12-10 13:25 ` Michael S. Tsirkin 2019-12-10 13:31 ` Paolo Bonzini 2019-12-10 16:02 ` Peter Xu 2019-12-10 21:53 ` Michael S. Tsirkin 2019-12-11 9:05 ` Paolo Bonzini 2019-12-11 13:04 ` Michael S. Tsirkin 2019-12-11 14:54 ` Peter Xu 2019-12-10 21:48 ` Michael S. Tsirkin 2019-12-11 12:53 ` Michael S. Tsirkin 2019-12-11 14:14 ` Paolo Bonzini 2019-12-11 20:59 ` Peter Xu 2019-12-11 22:57 ` Michael S. Tsirkin 2019-12-12 0:08 ` Paolo Bonzini 2019-12-12 7:36 ` Michael S. Tsirkin 2019-12-12 8:12 ` Paolo Bonzini [this message] 2019-12-12 10:38 ` Michael S. Tsirkin 2019-12-15 17:33 ` Peter Xu 2019-12-16 9:47 ` Michael S. Tsirkin 2019-12-16 15:07 ` Peter Xu 2019-12-16 15:33 ` Michael S. Tsirkin 2019-12-16 15:47 ` Peter Xu 2019-12-11 17:24 ` Christophe de Dinechin 2019-12-13 20:23 ` Peter Xu 2019-12-14 7:57 ` Paolo Bonzini 2019-12-14 16:26 ` Peter Xu 2019-12-16 9:29 ` Paolo Bonzini 2019-12-16 15:26 ` Peter Xu 2019-12-16 15:31 ` Paolo Bonzini 2019-12-16 15:43 ` Peter Xu 2019-12-17 12:16 ` Christophe de Dinechin 2019-12-17 12:19 ` Paolo Bonzini 2019-12-17 15:38 ` Peter Xu 2019-12-17 16:31 ` Paolo Bonzini 2019-12-17 16:42 ` Peter Xu 2019-12-17 16:48 ` Paolo Bonzini 2019-12-17 19:41 ` Peter Xu 2019-12-18 0:33 ` Paolo Bonzini 2019-12-18 16:32 ` Peter Xu 2019-12-18 16:41 ` Paolo Bonzini 2019-12-20 18:19 ` Peter Xu 2019-11-29 21:34 ` [PATCH RFC 05/15] KVM: Make dirty ring exclusive to dirty bitmap log Peter Xu 2019-11-29 21:34 ` [PATCH RFC 06/15] KVM: Introduce dirty ring wait queue Peter Xu 2019-11-29 21:34 ` [PATCH RFC 07/15] KVM: X86: Implement ring-based dirty memory tracking Peter Xu 2019-11-29 21:34 ` [PATCH RFC 08/15] KVM: selftests: Always clear dirty bitmap after iteration Peter Xu 2019-11-29 21:34 ` [PATCH RFC 09/15] KVM: selftests: Sync uapi/linux/kvm.h to tools/ Peter Xu 2019-11-29 21:35 ` [PATCH RFC 10/15] KVM: selftests: Use a single binary for dirty/clear log test Peter Xu 2019-11-29 21:35 ` [PATCH RFC 11/15] KVM: selftests: Introduce after_vcpu_run hook for dirty " Peter Xu 2019-11-29 21:35 ` [PATCH RFC 12/15] KVM: selftests: Add dirty ring buffer test Peter Xu 2019-11-29 21:35 ` [PATCH RFC 13/15] KVM: selftests: Let dirty_log_test async for dirty ring test Peter Xu 2019-11-29 21:35 ` [PATCH RFC 14/15] KVM: selftests: Add "-c" parameter to dirty log test Peter Xu 2019-11-29 21:35 ` [PATCH RFC 15/15] KVM: selftests: Test dirty ring waitqueue Peter Xu 2019-11-30 8:29 ` [PATCH RFC 00/15] KVM: Dirty ring interface Paolo Bonzini 2019-12-02 2:13 ` Peter Xu 2019-12-03 13:59 ` Paolo Bonzini 2019-12-05 19:30 ` Peter Xu 2019-12-05 19:59 ` Paolo Bonzini 2019-12-05 20:52 ` Peter Xu 2019-12-02 20:21 ` Sean Christopherson 2019-12-02 20:43 ` Peter Xu 2019-12-04 10:39 ` Jason Wang 2019-12-04 19:33 ` Peter Xu 2019-12-05 6:49 ` Jason Wang 2019-12-11 13:41 ` Christophe de Dinechin 2019-12-11 14:16 ` Paolo Bonzini 2019-12-11 17:15 ` Peter Xu
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