Re: [PATCH v2 2/2] xen/setup: Remap Xen Identity Mapped RAM

[Matthew Rushton]

On 08/01/14 07:52, David Vrabel wrote:
> On 31/07/14 18:43, David Vrabel wrote:
> > On 20/07/14 01:01, Matt Rushton wrote:
> > > Instead of ballooning up and down dom0 memory this remaps the existing mfns
> > > that were replaced by the identity map. The reason for this is that the
> > > existing implementation ballooned memory up and and down which caused dom0
> > > to have discontiguous pages. In some cases this resulted in the use of bounce
> > > buffers which reduced network I/O performance significantly. This change will
> > > honor the existing order of the pages with the exception of some boundary
> > > conditions.
> > >
> > > To do this we need to update both the Linux p2m table and the Xen m2p table.
> > > Particular care must be taken when updating the p2m table since it's important
> > > to limit table memory consumption and reuse the existing leaf pages which get
> > > freed when an entire leaf page is set to the identity map. To implement this,
> > > mapping updates are grouped into blocks with table entries getting cached
> > > temporarily and then released.
> > >
> > > On my test system before:
> > > Total pages: 2105014
> > > Total contiguous: 1640635
> > >
> > > After:
> > > Total pages: 2105014
> > > Total contiguous: 2098904
> > Applied to devel/for-linus-3.17
> Unfortunately, this produces too many WARNINGs on some boxes or
> with certain configurations.
>
> I will remove this patch from the queue for 3.17.

Have you had a chance to try the v3 patch set?


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