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Re: [Xen-devel] [PATCH 00 of 12] xenpaging fixes for xen-unstable

To: Olaf Hering <olaf@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 00 of 12] xenpaging fixes for xen-unstable
From: Keir Fraser <keir.xen@xxxxxxxxx>
Date: Wed, 08 Jun 2011 17:01:15 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
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Thread-topic: [Xen-devel] [PATCH 00 of 12] xenpaging fixes for xen-unstable
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On 07/06/2011 14:38, "Olaf Hering" <olaf@xxxxxxxxx> wrote:

> On Tue, Jun 07, Keir Fraser wrote:
>> Once they're in, what is left to do? Do you need help with the in-Xen
>> waitqueue stuff? Do you have test cases that fail, a private patch queue,
>> etc?
> Keir,
> I have no new patches, just returned to xenpaging end of last week.
> A few months ago I collected my TODO list below.
> One thing that I would need help with is the machine_to_phys_mapping[]
> handling, an attempt to fix it was reverted before the 4.1 release. See
> the thread in the URL below.

I'm taking a look at this. The hard way I describe in the referenced thread
seemed like a mistake when I tried it, so I'll sort out a simpler fix for
the original patch.

 -- Keir

> My testcase was a SLES11SP1 pv-on-hvm guest, rebooted in an endless
> loop. That catched all of the issues. With the
> waitqueue/HVMCOPY_gfn_paged_out issue its best to customize the
> xenpaging policy to page the range of gfns were the guest pagetables are
> stored.
> I will send a series of patches to try later.
> Olaf
> Todo:
> - implement xl support
> - implement stopping of xenpaging
> - implement live migration
> - implement config option for XENPAGING_DEBUG and XENPAGING_POLICY_MRU_SIZE
> - implement config option for xenpaging_dir
> - implement better starting gfn in xenpaging policy
>   an initial gfn number in the middle of the gfn range may avoid page-ins
>   during BIOS startup
> - fix machine_to_phys_mapping[] array handling during page deallocation
>   the gfn of a released page must be maintained properly in the array
>   http://lists.xensource.com/archives/html/xen-devel/2011-01/msg00824.html
> - fix HVMCOPY_gfn_paged_out handling
>   some callers of __hvm_copy() do not handle HVMCOPY_gfn_paged_out, such
>   as hypercalls and the MMIO emulation
>   the recently added waitqueue feature in Xen 4.1 should be used
> - remove all retry code from gfn_to_mfn() calls
>   use the waitqueue feature to hide page-in from the caller and cover
>   all cases where a retry is currently missing
> - do not bounce p2mt to xenpaging
>   p2m_mem_paging_populate/p2m_mem_paging_resume dont make use of p2mt
> - cleanup typeof gfn which is passed around in xenpaging
>   unsigned long, uint64_t, xen_pfn_t
> - cleanup return types of functions
>   some functions return 0 unconditionally, could be void
> - remove srand function

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