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Re: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast (de)inflating & fast live migration

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On 10/26/2016 03:06 AM, Li, Liang Z wrote:
> I am working on Dave's new bitmap schema, I have finished the part of
> getting the 'hybrid scheme bitmap' and found the complexity was more
> than I expected. The main issue is more memory is required to save
> the 'hybrid scheme bitmap' beside that used to save the raw page
> bitmap, for the worst case, the memory required is 3 times than that
> in the previous implementation.

Really?  Could you please describe the scenario where this occurs?

> I am wondering if I should continue, as an alternative solution, how about using PFNs array when
> inflating/deflating only a few pages? Things will be much more
> simple.

Yes, using pfn lists is more efficient than using bitmaps for sparse
bitmaps.  Yes, there will be cases where it is preferable to just use
pfn lists vs. any kind of bitmap.

But, what does it matter?  At least with your current scheme where we go
out and collect get_unused_pages(), we do the allocation up front.  The
space efficiency doesn't matter at all for small sizes since we do the
constant-size allocation *anyway*.

I'm also pretty sure you can pack the pfn and page order into a single
64-bit word and have no bitmap for a given record.  That would make it
pack just as well as the old pfns alone.  Right?

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[RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast (de)inflating & fast live migration Liang Li <liang.z.li@intel.com> - 2016-10-21 08:40 +0200
  [RESEND PATCH v3 kernel 4/7] virtio-balloon: speed up inflate/deflate process Liang Li <liang.z.li@intel.com> - 2016-10-21 08:40 +0200
    Re: [RESEND PATCH v3 kernel 4/7] virtio-balloon: speed up  inflate/deflate process "Michael S. Tsirkin" <mst@redhat.com> - 2016-10-25 08:40 +0200
      RE: [RESEND PATCH v3 kernel 4/7] virtio-balloon: speed up  inflate/deflate process "Li, Liang Z" <liang.z.li@intel.com> - 2016-10-25 11:50 +0200
  [RESEND PATCH v3 kernel 2/7] virtio-balloon: define new feature bit and page bitmap head Liang Li <liang.z.li@intel.com> - 2016-10-21 08:40 +0200
    Re: [RESEND PATCH v3 kernel 2/7] virtio-balloon: define new feature  bit and page bitmap head Dave Hansen <dave.hansen@intel.com> - 2016-10-24 19:00 +0200
      RE: [RESEND PATCH v3 kernel 2/7] virtio-balloon: define new feature  bit and page bitmap head "Li, Liang Z" <liang.z.li@intel.com> - 2016-10-25 03:30 +0200
    Re: [RESEND PATCH v3 kernel 2/7] virtio-balloon: define new feature  bit and page bitmap head "Michael S. Tsirkin" <mst@redhat.com> - 2016-10-26 17:50 +0200
  [RESEND PATCH v3 kernel 1/7] virtio-balloon: rework deflate to add page to a list Liang Li <liang.z.li@intel.com> - 2016-10-21 08:40 +0200
    Re: [RESEND PATCH v3 kernel 1/7] virtio-balloon: rework deflate to  add page to a list Dave Hansen <dave.hansen@intel.com> - 2016-10-24 18:50 +0200
      RE: [RESEND PATCH v3 kernel 1/7] virtio-balloon: rework deflate to  add page to a list "Li, Liang Z" <liang.z.li@intel.com> - 2016-10-25 03:20 +0200
  Re: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration Dave Hansen <dave.hansen@intel.com> - 2016-10-21 19:30 +0200
    Re: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration "Michael S. Tsirkin" <mst@redhat.com> - 2016-10-21 21:50 +0200
      RE: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration "Li, Liang Z" <liang.z.li@intel.com> - 2016-10-23 13:30 +0200
        Re: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration "Michael S. Tsirkin" <mst@redhat.com> - 2016-10-25 06:00 +0200
    RE: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration "Li, Liang Z" <liang.z.li@intel.com> - 2016-10-26 12:10 +0200
      RE: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration "Li, Liang Z" <liang.z.li@intel.com> - 2016-10-26 12:20 +0200
        Re: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration Dave Hansen <dave.hansen@intel.com> - 2016-10-26 20:20 +0200
          RE: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration "Li, Liang Z" <liang.z.li@intel.com> - 2016-10-27 02:40 +0200
      Re: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration Dave Hansen <dave.hansen@intel.com> - 2016-10-26 20:20 +0200
        RE: [RESEND PATCH v3 kernel 0/7] Extend virtio-balloon for fast  (de)inflating & fast live migration "Li, Liang Z" <liang.z.li@intel.com> - 2016-10-27 03:00 +0200

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