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Re: [Xen-devel] [PATCH][2/4] Enable 1GB for Xen HVM host page

To: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>, Wei Huang <wei.huang2@xxxxxxx>
Subject: Re: [Xen-devel] [PATCH][2/4] Enable 1GB for Xen HVM host page
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Tue, 23 Feb 2010 20:54:34 +0000
Cc: "Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] [PATCH][2/4] Enable 1GB for Xen HVM host page
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Save/restore/migrate will work just fine as is. You just won't get 1GB pages
at the receiving end.

 -- Keir

On 23/02/2010 20:09, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> Not sure what your point is.  I was just suggesting that if
> save/restore/migration doesn't work anyway, setting no_migrate
> should result in a nicer error message than otherwise, and serves
> as a clear "TO DO" marker for developers looking for a
> "fun" project.
> 
>> -----Original Message-----
>> From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
>> Sent: Tuesday, February 23, 2010 11:10 AM
>> To: Dan Magenheimer; Tim Deegan; Wei Huang
>> Cc: Keir@xxxxxxxxxxxxxxxxxxxx; Xu, Dongxiao; xen-
>> devel@xxxxxxxxxxxxxxxxxxx
>> Subject: Re: [Xen-devel] [PATCH][2/4] Enable 1GB for Xen HVM host page
>> 
>> The use of 1GB extents is just a (small-ish) performance win. If you
>> can
>> only back with 4kB or 2MB extents on the target host it doesn't matter
>> that
>> much.
>> 
>>  -- Keir
>> 
>> On 23/02/2010 17:19, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
>> wrote:
>> 
>>> I'll bet save/restore/migration for 1GB pages will be a fun
>> challenge.
>>> 
>>> At least please set the "no_migrate" flag automatically for
>>> any domain that uses 1GB pages unless/until live migration
>>> is supported.
>>> 
>>>> -----Original Message-----
>>>> From: Tim Deegan [mailto:Tim.Deegan@xxxxxxxxxx]
>>>> Sent: Tuesday, February 23, 2010 6:01 AM
>>>> To: Wei Huang
>>>> Cc: Keir@xxxxxxxxxxxxxxxxxxxx; Xu, Dongxiao; xen-
>>>> devel@xxxxxxxxxxxxxxxxxxx; Fraser
>>>> Subject: Re: [Xen-devel] [PATCH][2/4] Enable 1GB for Xen HVM host
>> page
>>>> 
>>>> At 17:18 +0000 on 22 Feb (1266859100), Wei Huang wrote:
>>>>> Change page allocation code in Xen tools. The allocation request
>> now
>>>>> starts with 1GB; if that fails, then falls back to 2MB and then
>> 4KB.
>>>> 
>>>> Can we have an equivalent patch for the save/restore path please?
>> That
>>>> took a while to catch up when 2MB superpages were introduced.
>>>> 
>>>> Tim.
>>>> 
>>>> --
>>>> Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>>>> Principal Software Engineer, XenServer Engineering
>>>> Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)
>>>> 
>>>> _______________________________________________
>>>> Xen-devel mailing list
>>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>>> http://lists.xensource.com/xen-devel
>> 
>> 



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