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Re: [Xen-devel] writable pagetables scalability issue

To: Rik van Riel <riel@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] writable pagetables scalability issue
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Fri, 07 Dec 2007 17:47:40 +0000
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On 7/12/07 17:06, "Rik van Riel" <riel@xxxxxxxxxx> wrote:

> Does anybody see issues with putting all of the writable pagetable
> operations under a read-write lock, with the code paths that change
> page table entries (mostly the fault handling) taking the lock in
> read mode, and the code paths that change the status of pages taking
> the lock in write mode?
> 
> That way we can guarantee that the writable page table pages do not
> change status while handling a fault (and we get concurrency), blocking
> out the write fault handling only while new page table pages are being
> created or destroyed.

I think we can probably just as easily strip out the big lock entirely from
the critical paths. It's not really needed much these days.

 -- Keir



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