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    |   xen-devel
Re: [Xen-devel] [PATCH] turn off writable page tables 
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On 29 Jul 2006, at 00:10, Zachary Amsden wrote:
 For SMP, the enter / leave must happen under protection of the page 
table
locks for page tables which are being modified.
 
This should be in a comment in the code
 
Most definitely agreed!  I think it deserves an entire paragraph 
explaining how to use it properly.  But I wanted to get input from the 
Xen folks to see if this can be useful for them in some way first.
 
It would allow set_pte() to switch between explicit queuing and 
'direct' writing. We moved away from the former a few years back as 
doing it everywhere made a mess of the generic Linux mm code and it was 
hard to reason whether our patches were correct. I guess doing it for 
the most important subset of mm routines is not so bad. It's a shame 
that, although many set_pte() call sites could determine statically 
whether or not they will batch, we'd end up with a dynamic run-time 
test everywhere (unless I'm mistaken) -- I wonder if that has a 
measurable cost? 
 -- Keir
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