From: Paolo Bonzini <pbonzini@redhat.com>
To: Christophe de Dinechin <dinechin@redhat.com>
Cc: Peter Xu <peterx@redhat.com>,
Christophe de Dinechin <christophe.de.dinechin@gmail.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: Tue, 17 Dec 2019 13:19:05 +0100
Message-ID: <d59ac0eb-e65a-a46f-886e-6df80a2b142f@redhat.com> (raw)
In-Reply-To: <E167A793-B42A-422D-8D46-B992CB6EBE69@redhat.com>
On 17/12/19 13:16, Christophe de Dinechin wrote:
>
>
>> On 14 Dec 2019, at 08:57, Paolo Bonzini <pbonzini@redhat.com> wrote:
>>
>> On 13/12/19 21:23, Peter Xu wrote:
>>>> What is the benefit of using u16 for that? That means with 4K pages, you
>>>> can share at most 256M of dirty memory each time? That seems low to me,
>>>> especially since it's sufficient to touch one byte in a page to dirty it.
>>>>
>>>> Actually, this is not consistent with the definition in the code ;-)
>>>> So I'll assume it's actually u32.
>>> Yes it's u32 now. Actually I believe at least Paolo would prefer u16
>>> more. :)
>>
>> It has to be u16, because it overlaps the padding of the first entry.
>
> Wow, now that’s subtle.
>
> That definitely needs a union with the padding to make this explicit.
>
> (My guess is you do that to page-align the whole thing and avoid adding a
> page just for the counters)
Yes, that was the idea but Peter decided to scrap it. :)
Paolo
>>
>> Paolo
>>
>>> I think even u16 would be mostly enough (if you see, the maximum
>>> allowed value currently is 64K entries only, not a big one). Again,
>>> the thing is that the userspace should be collecting the dirty bits,
>>> so the ring shouldn't reach full easily. Even if it does, we should
>>> probably let it stop for a while as explained above. It'll be
>>> inefficient only if we set it to a too-small value, imho.
>>>
>>
>
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
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 [this message]
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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