From: Wei Liu <wei.liu2@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>,
ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com,
xen-devel@lists.xen.org, david.vrabel@citrix.com,
boris.ostrovsky@oracle.com
Subject: Re: [PATCH RFC 00/10] Xen balloon page compaction support
Date: Wed, 15 Oct 2014 18:00:43 +0100 [thread overview]
Message-ID: <20141015170043.GF29948@zion.uk.xensource.com> (raw)
In-Reply-To: <543EA6C0.20903@citrix.com>
On Wed, Oct 15, 2014 at 05:54:24PM +0100, Andrew Cooper wrote:
> On 15/10/14 16:54, Wei Liu wrote:
> > Hi all
> >
> > This is a prototype to make Xen balloon driver work with balloon page
> > compaction. The goal is to reduce guest physical address space fragmentation
> > introduced by balloon pages. Having guest physical address space as contiguous
> > as possible is generally useful (because guest can have higher order pages), and
> > it should also help improve HVM performance (provided that guest kernel knows
> > how to use huge pages -- Linux has hugetlbfs and transparent huge page).
>
> After you have defragmented guest physical memory, does Linux use
> 2MB/1GB superpages more readily?
>
That's completely up to the guest. Having contiguous guest physical
address space is prerequisite.
> On what basis do you think this will improve HVM performance? The HAP
> tables still remain fragmented after ballooning.
>
That's the other side of this problem and orthogonal to this patch
series. It should be fixed separately on the hypervisor side, presumably
with similar mechanism to coalesce HAP table in hypervisor.
Wei.
> ~Andrew
next prev parent reply other threads:[~2014-10-15 17:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-15 15:54 [PATCH RFC 00/10] Xen balloon page compaction support Wei Liu
2014-10-15 15:54 ` [PATCH RFC 01/10] balloon_compaction: don't BUG() when it is not necessary Wei Liu
2014-10-15 15:54 ` [PATCH RFC 02/10] xen/balloon: fix code comment for free_xenballooned_pages Wei Liu
2014-10-15 15:54 ` [PATCH RFC 03/10] xen/balloon: consolidate data structures Wei Liu
2014-10-15 15:54 ` [PATCH RFC 04/10] xen/balloon: factor out function to update balloon stats Wei Liu
2014-10-15 15:54 ` [PATCH RFC 05/10] xen/balloon: rework increase_reservation Wei Liu
2014-10-15 15:54 ` [PATCH RFC 06/10] xen/balloon: make use of generic balloon driver Wei Liu
2014-10-15 15:54 ` [PATCH RFC 07/10] xen/balloon: factor out some helper functions Wei Liu
2014-10-15 15:54 ` [PATCH RFC 08/10] xen/balloon: implement migratepage Wei Liu
2014-10-15 16:16 ` David Vrabel
2014-10-16 9:28 ` Ian Campbell
2014-10-15 15:54 ` [PATCH RFC 09/10] balloon: BALLOON_COMPACTION now depends on XEN_BALLOON Wei Liu
2014-10-15 15:54 ` [PATCH RFC 10/10] XXX: balloon bitmap and sysrq key to dump bitmap Wei Liu
2014-10-15 16:25 ` [PATCH RFC 00/10] Xen balloon page compaction support David Vrabel
2014-10-15 16:30 ` Wei Liu
2014-10-16 9:31 ` David Vrabel
2014-10-15 16:54 ` Andrew Cooper
2014-10-15 17:00 ` Wei Liu [this message]
2014-10-15 17:14 ` Andrew Cooper
2014-10-16 9:12 ` Wei Liu
2014-10-16 9:26 ` Ian Campbell
2014-10-17 12:35 ` Andrew Cooper
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