>Have you got some lmbench results to back this up?
Does lmbench benchmark the _allocation_ of the memory? If so could you
point out to me the exact lmbench command? (you would save me the time for
writing such a simple bench ;). I looked a bit at lmbench and it seems to
me that all mm tools are measuring the time _after_ the allocation
happened (so measuring the hardware bus/cache speed or page-colouring
algorithms and not the OS anonymous/shm page-fault time). But maybe I am
overlooking something?
All bw_mem_rw/bw_mem_cp/bw_mem_rd are _useless_ to benchmark the bigmem
patch since as just said once the allocation of memory is completed the
performance decrease will be _zero_ and not only close to zero.
The only tiny performance hit will happens while allocating a page for
clearing it or for doing the COW inside the page-fault handler (if you
are going to benchmark it make sure to #undef KMAP_DEBUG).
Andrea
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