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Re: [Xen-devel] Regarding page table management changes from Xen v1 to X

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Regarding page table management changes from Xen v1 to Xen v2 (and v3)
From: Himanshu Raj <rhim@xxxxxxxxxxxxx>
Date: Wed, 26 Apr 2006 13:56:48 -0400
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Thanks Keir for your prompt reply. 

In another example, mmapped access to a file, the new approach will incur these
two extra faults for every page fault required to bring a file page to page 
cache,
right?

Could you tell me another example other than fork when one can use batched PTE
modifications.

Thanks and best regards,
Himanshu

On Wed, Apr 26, 2006 at 06:44:24PM +0100, Keir Fraser wrote:
> 
> On 26 Apr 2006, at 18:40, Himanshu Raj wrote:
> 
> >Although, same results can be obtained by doing the v1.2 way, i.e. 
> >making one
> >hypercall requesting these 1024 changes, no?
> >
> >-Himanshu
> 
> You have to marshal/unmarshal the batched arguments, and insert flushes 
> all over the place to ensure the requests get flushed before Linux next 
> tries to read any of the ptes. So the new method is fewer changes to 
> the guest and no slower for reasonable-sized batches.
> 
>  -- Keir

-- 
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Himanshu Raj
PhD Student, GaTech (www.cc.gatech.edu/~rhim)
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