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Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate process

From "Michael S. Tsirkin" <mst@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate process
Date 2016-07-29 00:20 +0200
Message-ID <s01ON-40K-5@gated-at.bofh.it> (permalink)
References <rZlZf-1d6-3@gated-at.bofh.it> <rZlZf-1d6-1@gated-at.bofh.it> <rZzzb-1Cb-7@gated-at.bofh.it> <rZEIy-4S2-17@gated-at.bofh.it> <rZKkW-s6-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Thu, Jul 28, 2016 at 03:30:09AM +0000, Li, Liang Z wrote:
> > Subject: Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate
> > process
> > 
> > On Wed, Jul 27, 2016 at 09:03:21AM -0700, Dave Hansen wrote:
> > > On 07/26/2016 06:23 PM, Liang Li wrote:
> > > > +	vb->pfn_limit = VIRTIO_BALLOON_PFNS_LIMIT;
> > > > +	vb->pfn_limit = min(vb->pfn_limit, get_max_pfn());
> > > > +	vb->bmap_len = ALIGN(vb->pfn_limit, BITS_PER_LONG) /
> > > > +		 BITS_PER_BYTE + 2 * sizeof(unsigned long);
> > > > +	hdr_len = sizeof(struct balloon_bmap_hdr);
> > > > +	vb->bmap_hdr = kzalloc(hdr_len + vb->bmap_len, GFP_KERNEL);
> > >
> > > This ends up doing a 1MB kmalloc() right?  That seems a _bit_ big.
> > > How big was the pfn buffer before?
> > 
> > 
> > Yes I would limit this to 1G memory in a go, will result in a 32KByte bitmap.
> > 
> > --
> > MST
> 
> Limit to 1G is bad for the performance, I sent you the test result several weeks ago.
> 
> Paste it bellow:
> ------------------------------------------------------------------------------------------------------------------------
> About the size of page bitmap, I have test the performance of filling the balloon to 15GB with a
>  16GB RAM VM.
> 
> ===============================
> 32K Byte (cover 1GB of RAM)
> 
> Time spends on inflating: 2031ms
> ---------------------------------------------
> 64K Byte (cover 2GB of RAM)
> 
> Time spends on inflating: 1507ms
> --------------------------------------------
> 512K Byte (cover 16GB of RAM)
> 
> Time spends on inflating: 1237ms
> ================================
> 
> If possible, a big bitmap is better for performance.
> 
> Liang

Earlier you said:
a. allocating pages (6.5%)
b. sending PFNs to host (68.3%)
c. address translation (6.1%)
d. madvise (19%)

Here sending PFNs to host with 512K Byte map
should be almost free.

So is something else taking up the time?


-- 
MST

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[PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate process Liang Li <liang.z.li@intel.com> - 2016-07-27 03:40 +0200
  Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process Dave Hansen <dave.hansen@intel.com> - 2016-07-27 18:10 +0200
    Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Michael S. Tsirkin" <mst@redhat.com> - 2016-07-27 23:40 +0200
      RE: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Li, Liang Z" <liang.z.li@intel.com> - 2016-07-28 05:40 +0200
        Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Michael S. Tsirkin" <mst@redhat.com> - 2016-07-29 00:20 +0200
          RE: [virtio-dev] Re: [PATCH v2 repost 4/7] virtio-balloon: speed up  inflate/deflate process "Li, Liang Z" <liang.z.li@intel.com> - 2016-07-29 03:10 +0200
    RE: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Li, Liang Z" <liang.z.li@intel.com> - 2016-07-28 03:20 +0200
      Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Michael S. Tsirkin" <mst@redhat.com> - 2016-07-28 03:50 +0200
        RE: [virtio-dev] Re: [PATCH v2 repost 4/7] virtio-balloon: speed up  inflate/deflate process "Li, Liang Z" <liang.z.li@intel.com> - 2016-07-28 08:40 +0200
          Re: [virtio-dev] Re: [PATCH v2 repost 4/7] virtio-balloon: speed up  inflate/deflate process "Michael S. Tsirkin" <mst@redhat.com> - 2016-07-29 00:00 +0200
            RE: [virtio-dev] Re: [PATCH v2 repost 4/7] virtio-balloon: speed up  inflate/deflate process "Li, Liang Z" <liang.z.li@intel.com> - 2016-07-29 02:50 +0200
            Re: [virtio-dev] Re: [PATCH v2 repost 4/7] virtio-balloon: speed up  inflate/deflate process Dave Hansen <dave.hansen@intel.com> - 2016-07-29 21:50 +0200
              RE: [virtio-dev] Re: [PATCH v2 repost 4/7] virtio-balloon: speed up  inflate/deflate process "Li, Liang Z" <liang.z.li@intel.com> - 2016-08-02 02:40 +0200
  Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Michael S. Tsirkin" <mst@redhat.com> - 2016-07-27 23:40 +0200
    RE: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Li, Liang Z" <liang.z.li@intel.com> - 2016-07-28 05:10 +0200
      Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Michael S. Tsirkin" <mst@redhat.com> - 2016-07-29 00:20 +0200
        RE: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Li, Liang Z" <liang.z.li@intel.com> - 2016-07-29 02:40 +0200
  Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Michael S. Tsirkin" <mst@redhat.com> - 2016-07-28 00:10 +0200
    RE: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate  process "Li, Liang Z" <liang.z.li@intel.com> - 2016-07-28 05:50 +0200

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