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DateSun, 20 Jan 2002 22:30:26 -0700
FromRichard Gooch <>
SubjectRe: Linux 2.4.18pre3-ac1
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Daniel Phillips writes:
The way I see it, the purpose of lazy page table instantiation is to overcome objections to the reverse pte mapping vm technique that have been expressed in the past, namely the slowdown in dup_mmap inside fork. I.e., if rmap slows down fork then Linus and Davem are going to veto it, as they've done in the past, because they feel that the as-yet-unproven advantages of physically-based vm scanning doesn't outweigh the easily measurable fork overhead. Personally, I think that's debatable, but by eliminating the overhead we eliminate the objection, and as far as I know, it's the only serious objection.

Will lazy page table instantiation speed up fork(2) without rmap? If so, then you've got a problem, because rmap will still be slower than non-rmap. Linus will happily grab any speedup and make that the new baseline against which new schemes are compared :-)
Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca
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