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Date: Wed, 23 Nov 2005 14:21:53 -0800 (PST)
From: Linus Torvalds <torvalds@osdl.org>
To: "H. Peter Anvin" <hpa@zytor.com>
cc: Daniel Jacobowitz <dan@debian.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
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Subject: Re: [patch] SMP alternatives
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On Wed, 23 Nov 2005, H. Peter Anvin wrote:
> 
> Yes.  Any shared mmaps may require working lock.

Not "any". Only writable shared mmap. Which is actually the rare case.

Even then, we might want to have such processes have a way to say "I don't 
do futexes in this mmap" or similar. Quite often, writable shared mmaps 
aren't interested in locked cycles - they are there to just write things 
to disk, and all the serialization is done in the kernel when the user 
does a "munmap()" or a "msync()".

		Linus
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