tree 65a4d1f18a93a9e89d43fe0b8e0b3009675c50f0
parent 40193713df2cdb9c233b3fc2029ecdccb40cb1e4
author Nick Piggin <nickpiggin@yahoo.com.au> 1125211751 +1000
committer Linus Torvalds <torvalds@g5.osdl.org> 1125361504 -0700

[PATCH] Lazy page table copies in fork()

Defer copying of ptes until fault time when it is possible to reconstruct
the pte from backing store. Idea from Andi Kleen and Nick Piggin.

Thanks to input from Rik van Riel and Linus and to Hugh for correcting
my blundering.

Ray Fucillo <fucillo@intersystems.com> reports:

  "I applied this latest patch to a 2.6.12 kernel and found that it does
   resolve the problem.  Prior to the patch on this machine, I was
   seeing about 23ms spent in fork for ever 100MB of shared memory
   segment.

   After applying the patch, fork is taking about 1ms regardless of the
   shared memory size."

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>