> > It's only small because it makes you rescan the free list.
> > So maybe you should do something else.
> > I looked at it a bit. Instead of scanning the free list, how about
> > scanning actual page structures? If page is unused, pass it to host.
> > Solves the problem of rescanning multiple tim
On 07/28/2016 02:51 PM, Michael S. Tsirkin wrote:
>> > If 1MB is too big, how about 512K, or 256K? 32K seems too small.
>> >
> It's only small because it makes you rescan the free list.
> So maybe you should do something else.
> I looked at it a bit. Instead of scanning the free list, how about
>
> > > 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_P
> On Thu, Jul 28, 2016 at 06:36:18AM +, Li, Liang Z wrote:
> > > > > This ends up doing a 1MB kmalloc() right? That seems a _bit_ big.
> > > > > How big was the pfn buffer before?
> > > >
> > > > Yes, it is if the max pfn is more than 32GB.
> > > > The size of the pfn buffer use before is 256*
> On Thu, Jul 28, 2016 at 03:06:37AM +, Li, Liang Z wrote:
> > > > + * VIRTIO_BALLOON_PFNS_LIMIT is used to limit the size of page
> > > > +bitmap
> > > > + * to prevent a very large page bitmap, there are two reasons for this:
> > > > + * 1) to save memory.
> > > > + * 2) allocate a large bitm
On Thu, Jul 28, 2016 at 03:06:37AM +, Li, Liang Z wrote:
> > > + * VIRTIO_BALLOON_PFNS_LIMIT is used to limit the size of page bitmap
> > > + * to prevent a very large page bitmap, there are two reasons for this:
> > > + * 1) to save memory.
> > > + * 2) allocate a large bitmap may fail.
> > >
On Thu, Jul 28, 2016 at 03:30:09AM +, 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 wro
On Thu, Jul 28, 2016 at 06:36:18AM +, Li, Liang Z wrote:
> > > > This ends up doing a 1MB kmalloc() right? That seems a _bit_ big.
> > > > How big was the pfn buffer before?
> > >
> > > Yes, it is if the max pfn is more than 32GB.
> > > The size of the pfn buffer use before is 256*4 = 1024 Byt
> > > This ends up doing a 1MB kmalloc() right? That seems a _bit_ big.
> > > How big was the pfn buffer before?
> >
> > Yes, it is if the max pfn is more than 32GB.
> > The size of the pfn buffer use before is 256*4 = 1024 Bytes, it's too
> > small, and it's the main reason for bad performance.
>
> > +/*
> > + * VIRTIO_BALLOON_PFNS_LIMIT is used to limit the size of page bitmap
> > + * to prevent a very large page bitmap, there are two reasons for this:
> > + * 1) to save memory.
> > + * 2) allocate a large bitmap may fail.
> > + *
> > + * The actual limit of pfn is determined by:
> > + * p
> 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;
> > &
> > + * VIRTIO_BALLOON_PFNS_LIMIT is used to limit the size of page bitmap
> > + * to prevent a very large page bitmap, there are two reasons for this:
> > + * 1) to save memory.
> > + * 2) allocate a large bitmap may fail.
> > + *
> > + * The actual limit of pfn is determined by:
> > + * pfn_limit
On Thu, Jul 28, 2016 at 01:13:35AM +, Li, Liang Z wrote:
> > Subject: Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate
> > process
> >
> > On 07/26/2016 06:23 PM, Liang Li wrote:
> > > + vb->pfn_limit = VIRTIO_BALLOON_PFNS_LIMIT;
>
> Subject: Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate
> process
>
> 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());
> >
On Wed, Jul 27, 2016 at 09:23:33AM +0800, Liang Li wrote:
> The implementation of the current virtio-balloon is not very
> efficient, the time spends on different stages of inflating
> the balloon to 7GB of a 8GB idle guest:
>
> a. allocating pages (6.5%)
> b. sending PFNs to host (68.3%)
> c. add
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
On Wed, Jul 27, 2016 at 09:23:33AM +0800, Liang Li wrote:
> The implementation of the current virtio-balloon is not very
> efficient, the time spends on different stages of inflating
> the balloon to 7GB of a 8GB idle guest:
>
> a. allocating pages (6.5%)
> b. sending PFNs to host (68.3%)
> c. add
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(str
The implementation of the current virtio-balloon is not very
efficient, the time spends on different stages of inflating
the balloon to 7GB of a 8GB idle guest:
a. allocating pages (6.5%)
b. sending PFNs to host (68.3%)
c. address translation (6.1%)
d. madvise (19%)
It takes about 4126ms for the
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