Re: What to expect with the 2.6 VM

[Jamie Lokier <jamie@shareable.org>]

Andrea Arcangeli wrote:
> so you agree it'd better be a separate syscall

Per-page protections might be workable just through mremap().  As you
say, it's just a matter of appropriate bits in the swap entry.  To
userspace it is a transparent performance improvement.

Unfortunately without an appropriate bit in the pte too, that
restricts per-page protections to work only with shared mappings, or
anon mappings which have not been forked, due to the lack of COW.  It
would still be a good optimisation, although it would be a shame if,
say, a GC implementation of malloc et al. (eg. Boehm's allocator)
would not be transparent over fork().

-- Jamie
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