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Re: [PATCH kernel v5 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration

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>>>
>>> I did something similar. Filled the balloon with 15GB for a 16GB idle
>>> guest, by
>>> using bitmap, the madvise count was reduced to 605. when using the
>>> PFNs, the madvise count
>>> was 3932160. It means there are quite a lot consecutive bits in the
>>> bitmap.
>>> I didn't test for a guest with heavy memory workload.
>>
>> Would it then even make sense to go one step further and report {pfn,
>> length} combinations?
>>
>> So simply send over an array of {pfn, length}?
>
> Li's current patches do that.  Well, maybe not pfn/length, but they do
> take a pfn and page-order, which fits perfectly with the kernel's
> concept of high-order pages.

So we can send length in powers of two. Still, I don't see any benefit
over a simple pfn/len schema. But I'll have a more detailed look at the
implementation first, maybe that will enlighten me :)

>
>> And it makes sense if you think about:
>>
>> a) hugetlb backing: The host may only be able to free huge pages (we
>> might want to communicate that to the guest later, that's another
>> story). Still we would have to send bitmaps full of 4k frames (512 bits
>> for 2mb frames). Of course, we could add a way to communicate that we
>> are using a different bitmap-granularity.
>
> Yeah, please read the patches.  If they're not clear, then the
> descriptions need work, but this is done already.
>

I missed the page_shift, thanks for the hint.

-- 

David

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[PATCH kernel v5 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration Liang Li <liang.z.li@intel.com> - 2016-11-30 10:00 +0100
  [PATCH kernel v5 5/5] virtio-balloon: tell host vm's unused page info Liang Li <liang.z.li@intel.com> - 2016-11-30 10:00 +0100
    Re: [PATCH kernel v5 5/5] virtio-balloon: tell host vm's unused page  info Dave Hansen <dave.hansen@intel.com> - 2016-11-30 20:20 +0100
      RE: [PATCH kernel v5 5/5] virtio-balloon: tell host vm's unused  page info "Li, Liang Z" <liang.z.li@intel.com> - 2016-12-04 14:20 +0100
        Re: [PATCH kernel v5 5/5] virtio-balloon: tell host vm's unused page  info Dave Hansen <dave.hansen@intel.com> - 2016-12-05 18:30 +0100
          RE: [PATCH kernel v5 5/5] virtio-balloon: tell host vm's unused  page info "Li, Liang Z" <liang.z.li@intel.com> - 2016-12-06 05:50 +0100
  [PATCH kernel v5 2/5] virtio-balloon: define new feature bit and head struct Liang Li <liang.z.li@intel.com> - 2016-11-30 10:00 +0100
  [PATCH kernel v5 4/5] virtio-balloon: define flags and head for host request vq Liang Li <liang.z.li@intel.com> - 2016-11-30 10:00 +0100
  [PATCH kernel v5 1/5] virtio-balloon: rework deflate to add page to a list Liang Li <liang.z.li@intel.com> - 2016-11-30 10:00 +0100
  Re: [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration David Hildenbrand <david@redhat.com> - 2016-12-06 09:50 +0100
    RE: [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration "Li, Liang Z" <liang.z.li@intel.com> - 2016-12-07 14:40 +0100
      Re: [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration Dave Hansen <dave.hansen@intel.com> - 2016-12-07 16:40 +0100
        RE: [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration "Li, Liang Z" <liang.z.li@intel.com> - 2016-12-09 04:10 +0100
      Re: [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration Dave Hansen <dave.hansen@intel.com> - 2016-12-07 16:50 +0100
        Re: [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration David Hildenbrand <david@redhat.com> - 2016-12-07 17:30 +0100
          Re: [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration Dave Hansen <dave.hansen@intel.com> - 2016-12-07 18:00 +0100
            Re: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for  fast (de)inflating & fast live migration Andrea Arcangeli <aarcange@redhat.com> - 2016-12-07 19:40 +0100
              Re: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration Dave Hansen <dave.hansen@intel.com> - 2016-12-07 20:00 +0100
                Re: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for  fast (de)inflating & fast live migration Andrea Arcangeli <aarcange@redhat.com> - 2016-12-07 20:00 +0100
              Re: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration Dave Hansen <dave.hansen@intel.com> - 2016-12-07 21:00 +0100
                Re: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for  fast (de)inflating & fast live migration Andrea Arcangeli <aarcange@redhat.com> - 2016-12-07 21:30 +0100
                RE: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for  fast (de)inflating & fast live migration "Li, Liang Z" <liang.z.li@intel.com> - 2016-12-09 05:50 +0100
                Re: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration Dave Hansen <dave.hansen@intel.com> - 2016-12-09 06:00 +0100
                RE: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for  fast (de)inflating & fast live migration "Li, Liang Z" <liang.z.li@intel.com> - 2016-12-09 06:40 +0100
                Re: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for  fast (de)inflating & fast live migration Andrea Arcangeli <aarcange@redhat.com> - 2016-12-09 17:50 +0100
      Re: [PATCH kernel v5 0/5] Extend virtio-balloon for fast  (de)inflating & fast live migration David Hildenbrand <david@redhat.com> - 2016-12-07 16:50 +0100

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