Messages in this thread | | | Date | Mon, 16 Aug 1999 19:19:46 +0200 (CEST) | From | Andrea Arcangeli <> | Subject | Re: [bigmem-patch] 4GB with Linux on IA32 |
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On Mon, 16 Aug 1999, Matthew Wilcox wrote:
>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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