Re: [Xen-devel] One question on alloc_bitmap

Keir Fraser
Mon, 22 Sep 2008 07:03:05 -0000

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[].

 -- 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
>>>
>>>
>>>
>>> _______________________________________________
>>> Xen-devel mailing list
>>> Xen-devel@lists.xensource.com
>>> http://lists.xensource.com/xen-devel