[patch] swap-speedup-2.4.3-B3

[Ingo Molnar]

the latest swap-speedup patch can be found at:

  http://people.redhat.com/mingo/swap-speedup/swap-speedup-2.4.3-B3

(the patch is against 2.4.4-pre6 or 2.4.3-ac13.)

-B3 includes Marcelo's patch for another area that blocks unnecesserily on
locked swapcache pages: async swapcache readahead. Marcello did some tests
which shows that this fix brought some nice improvements too.

"make -j32 bzImage" using 128MB mem, 128MB swap, 4 CPUs:

  stock 2.4.3-ac13
  ----------------
  real    4m0.678s
  user    4m2.870s
  sys     0m38.920s

  swap-speedup-A2
  ---------------
  real    3m24.190s
  user    4m1.070s
  sys     0m31.950s

  swap-speedup-B3 (A2 + Marcelo's swapin-readahead non-blocking patch)
  ---------------
  real    3m7.410s
  user    4m0.940s
  sys     0m28.680s

ie. for this kernel compile test:

   swap-speedup-A2 is a 18% speedup relative to stock 2.4.3-ac13
   swap-speedup-B3 is a 28% speedup relative to stock 2.4.3-ac13

and the amount of CPU time spent in the kernel has been reduced
significantly as well.

I believe all the correctness and SMP-locking issues have been taken care
of in -B3 as well.

	Ingo