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From: Peter Xu <peterx@redhat.com>
To: Jason Wang <jasowang@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH RFC 00/15] KVM: Dirty ring interface
Date: Wed, 4 Dec 2019 14:33:57 -0500
Message-ID: <20191204193357.GE19939@xz-x1> (raw)
In-Reply-To: <776732ca-06c8-c529-0899-9d2ffacf7789@redhat.com>

On Wed, Dec 04, 2019 at 06:39:48PM +0800, Jason Wang wrote:
> 
> On 2019/11/30 上午5:34, Peter Xu wrote:
> > Branch is here:https://github.com/xzpeter/linux/tree/kvm-dirty-ring
> > 
> > Overview
> > ============
> > 
> > This is a continued work from Lei Cao<lei.cao@stratus.com>  and Paolo
> > on the KVM dirty ring interface.  To make it simple, I'll still start
> > with version 1 as RFC.
> > 
> > The new dirty ring interface is another way to collect dirty pages for
> > the virtual machine, but it is different from the existing dirty
> > logging interface in a few ways, majorly:
> > 
> >    - Data format: The dirty data was in a ring format rather than a
> >      bitmap format, so the size of data to sync for dirty logging does
> >      not depend on the size of guest memory any more, but speed of
> >      dirtying.  Also, the dirty ring is per-vcpu (currently plus
> >      another per-vm ring, so total ring number is N+1), while the dirty
> >      bitmap is per-vm.
> > 
> >    - Data copy: The sync of dirty pages does not need data copy any more,
> >      but instead the ring is shared between the userspace and kernel by
> >      page sharings (mmap() on either the vm fd or vcpu fd)
> > 
> >    - Interface: Instead of using the old KVM_GET_DIRTY_LOG,
> >      KVM_CLEAR_DIRTY_LOG interfaces, the new ring uses a new interface
> >      called KVM_RESET_DIRTY_RINGS when we want to reset the collected
> >      dirty pages to protected mode again (works like
> >      KVM_CLEAR_DIRTY_LOG, but ring based)
> > 
> > And more.
> 
> 
> Looks really interesting, I wonder if we can make this as a library then we
> can reuse it for vhost.

So iiuc this ring will majorly for (1) data exchange between kernel
and user, and (2) shared memory.  I think from that pov yeh it should
work even for vhost.

It shouldn't be hard to refactor the interfaces to avoid kvm elements,
however I'm not sure how to do that best.  Maybe like irqbypass and
put it into virt/lib/ as a standlone module?  Would it worth it?

Paolo, what's your take?

-- 
Peter Xu


  reply index

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-29 21:34 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
2019-12-03 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 17:24   ` Christophe de Dinechin
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 [this message]
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
  -- strict thread matches above, loose matches on Subject: below --
2019-11-29 21:33 Peter Xu
2019-11-29 21:32 Peter Xu

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