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From: Jason Wang <jasowang@redhat.com>
To: Peter Xu <peterx@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	Christophe de Dinechin <dinechin@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH RESEND v2 00/17] KVM: Dirty ring interface
Date: Tue, 24 Dec 2019 14:34:45 +0800	[thread overview]
Message-ID: <5e859f76-96a2-634e-c26e-17421af7022a@redhat.com> (raw)
In-Reply-To: <20191221014938.58831-1-peterx@redhat.com>


On 2019/12/21 上午9:49, Peter Xu wrote:
> * Why not virtio?
>
> There's already some discussion during v1 patchset on whether it's
> good to use virtio for the data path of delivering dirty pages [1].
> I'd confess the only thing that we might consider to use is the vring
> layout (because virtqueue is tightly bound to devices, while we don't
> have a device contet here), however it's a pity that even we only use
> the most low-level vring api it'll be at least iov based which is
> already an overkill for dirty ring (which is literally an array of
> addresses).  So I just kept things easy.


If iov is the only reason, we can simple extend vringh helper to access 
the descriptor directly.

For split ring, it has some redundant stuffs.

- dirty ring has simple assumption used_idx = last_avail_idx (which is 
fetch_index), so no need for having two rings
- descriptor is self contained (dirty_gfns), no need to another 
indirection (but we can reuse vring descriptors for sure)

For packed ring, it looks not, but I'm not sure it's worthwhile to try.

Thanks


      parent reply	other threads:[~2019-12-24  6:35 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-21  1:49 Peter Xu
2019-12-21  1:49 ` [PATCH RESEND v2 01/17] KVM: Remove kvm_read_guest_atomic() Peter Xu
2020-01-08 17:45   ` Paolo Bonzini
2019-12-21  1:49 ` [PATCH RESEND v2 02/17] KVM: X86: Change parameter for fast_page_fault tracepoint Peter Xu
2020-01-08 17:46   ` Paolo Bonzini
2019-12-21  1:49 ` [PATCH RESEND v2 03/17] KVM: X86: Don't track dirty for KVM_SET_[TSS_ADDR|IDENTITY_MAP_ADDR] Peter Xu
2019-12-21 13:51   ` Paolo Bonzini
2019-12-23 17:27     ` Peter Xu
2019-12-23 17:59       ` Paolo Bonzini
2019-12-23 20:10         ` Peter Xu
2020-01-08 17:46           ` Paolo Bonzini
2020-01-08 19:15             ` Peter Xu
2020-01-08 19:44               ` Paolo Bonzini
2020-01-08 21:02                 ` Peter Xu
2019-12-21  1:49 ` [PATCH RESEND v2 04/17] KVM: Cache as_id in kvm_memory_slot Peter Xu
2020-01-08 17:47   ` Paolo Bonzini
2019-12-21  1:49 ` [PATCH RESEND v2 05/17] KVM: Add build-time error check on kvm_run size Peter Xu
2019-12-21  1:49 ` [PATCH RESEND v2 06/17] KVM: Pass in kvm pointer into mark_page_dirty_in_slot() Peter Xu
2020-01-08 17:47   ` Paolo Bonzini
2019-12-21  1:49 ` [PATCH RESEND v2 07/17] KVM: Move running VCPU from ARM to common code Peter Xu
2020-01-08 17:47   ` Paolo Bonzini
2019-12-21  1:49 ` [PATCH RESEND v2 08/17] KVM: X86: Implement ring-based dirty memory tracking Peter Xu
2019-12-24  6:16   ` Jason Wang
2019-12-24 15:08     ` Peter Xu
2019-12-25  3:23       ` Jason Wang
2020-01-08 15:52   ` Peter Xu
2020-01-08 17:41     ` Paolo Bonzini
2020-01-08 19:06       ` Peter Xu
2020-01-08 19:44         ` Paolo Bonzini
2020-01-08 19:59           ` Peter Xu
2020-01-08 20:06             ` Paolo Bonzini
2019-12-21  1:49 ` [PATCH RESEND v2 09/17] KVM: Make dirty ring exclusive to dirty bitmap log Peter Xu
2019-12-21  1:58 ` [PATCH RESEND v2 10/17] KVM: Don't allocate dirty bitmap if dirty ring is enabled Peter Xu
2019-12-21  2:04 ` [PATCH RESEND v2 11/17] KVM: selftests: Always clear dirty bitmap after iteration Peter Xu
2019-12-21  2:04 ` [PATCH RESEND v2 12/17] KVM: selftests: Sync uapi/linux/kvm.h to tools/ Peter Xu
2019-12-21  2:04 ` [PATCH RESEND v2 13/17] KVM: selftests: Use a single binary for dirty/clear log test Peter Xu
2019-12-21  2:04 ` [PATCH RESEND v2 14/17] KVM: selftests: Introduce after_vcpu_run hook for dirty " Peter Xu
2019-12-21  2:04 ` [PATCH RESEND v2 15/17] KVM: selftests: Add dirty ring buffer test Peter Xu
2019-12-24  6:18   ` Jason Wang
2019-12-24 15:22     ` Peter Xu
2019-12-24  6:50   ` Jason Wang
2019-12-24 15:24     ` Peter Xu
2019-12-21  2:04 ` [PATCH RESEND v2 16/17] KVM: selftests: Let dirty_log_test async for dirty ring test Peter Xu
2019-12-21  2:04 ` [PATCH RESEND v2 17/17] KVM: selftests: Add "-c" parameter to dirty log test Peter Xu
2019-12-24  6:34 ` Jason Wang [this message]

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