[Pkg-gauche-devel] threads and fork on machine with VIPT-WB cache
NIIBE Yutaka
gniibe at fsij.org
Fri Apr 2 03:48:11 UTC 2010
Thanks for your quick reply.
James Bottomley wrote:
> In COW breaking, the page table entry is copied, so A and B no longer
> have page table entries at the same physical location. If the COW is
> intact, A and B have the same physical page, but it's also accessed by
> the same virtual address, hence no aliasing.
Let me explain more.
In the scenario, I assume:
No aliasing between A and B.
We have aliasing between kernel access and user access.
Before COW breaking A and B share same data (with no aliasing same
space identifier color), and B sees data in cache, while memory has
stale data.
At COW breaking, kernel copies the memory, it doesn't see new data
in cache because of aliasing.
Isn't it possible?
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