RE: [Xen-devel] One question on alloc_bitmap

Jiang, Yunhong
Mon, 22 Sep 2008 07:50:34 -0000

Keir Fraser <mailto:keir.fraser@eu.citrix.com>
wrote:
> Um, I was suggesting we *don''t* use an explicit radix tree in
> this case (I
> assume Dan has a diffeent scenario where he actually requires
> an explicit
> radix tree structure). For alloc_bitmap[] we can stitch
> together a linear
> virtual address space using page tables, just as we do for frame_table[].

We were working on using the virtual address method like frame_table. I asked
patch from Dan just because I thought he already implemented patch for this and
want to avoid conflct. If he is using radix tree for other purpose,
that''s ok.

Yunhong Jiang

>
> -- Keir
>
> On 22/9/08 06:35, "Jiang, Yunhong"
<yunhong.jiang@intel.com> wrote:
>
>> Sure, can you please share the patch to avoid duplicate patch?
>>
>> Thanks
>> Yunhong Jiang
>>
>> Daniel Magenheimer <mailto:dan.magenheimer@oracle.com> wrote:
>>> FYI, I''m working on a patch that requires radix trees and
>>> have borrowed a bunch of code from Linux for it.  I had
>>> to make a few changes to generalize the code (e.g.
>>> callouts for node alloc/free); if it would be useful,
>>> please let me know and I will post it.
>>>
>>>> -----Original Message-----
>>>> From: Keir Fraser [mailto:keir.fraser@eu.citrix.com]
>>>> Sent: Friday, September 19, 2008 3:32 AM
>>>> To: Jiang, Yunhong; xen-devel@lists.xensource.com; Wang, Shane
>>>> Subject: Re: [Xen-devel] One question on alloc_bitmap
>>>>
>>>>
>>>> On 19/9/08 10:17, "Jiang, Yunhong"
<yunhong.jiang@intel.com> wrote:
>>>>
>>>>>>> Any idea on it?
>>>>>>
>>>>>> Yes, it could be sparsely allocated in future. No
reason why not.
>>>>>
>>>>> Thanks for your clarification. We ask this because we are
considering
>>>>> memory online.
>>>>
>>>> I would suggest we allocate a virtual address range for the
>>>> bitmap and then
>>>> demand-populate mappings in that area. Just as we do for the
frame_table.
>>>>
>>>> The alternative is an explicit radix tree data structure, but
>>>> we may as well
>>>> make use of the page-table structures to do the lookup work for
us.
>>>>
>>>>  -- Keir
>>>>
>>>>
>>>>
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