Messages in this thread | | | From | "Albert D. Cahalan" <> | Subject | Re: bigphysarea support in 2.2.19 and 2.4.0 kernels | Date | Sun, 24 Dec 2000 03:15:45 -0500 (EST) |
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Jes Sorensen writes: > Albert D Cahalan <acahalan@cs.uml.edu> writes:
[about using huge physical allocations for number crunching]
>> 2. Programming a DMA controller with multiple addresses isn't >> as fast as programming it with one. > > LOL > > Consider that allocating the larger block of memory is going > to take a lot longer than it will take for the DMA engine to > read the scatter/gather table entries and fetch a new address > word now and then.
Say it takes a whole minute to allocate the memory. It wouldn't of course, because you'd allocate memory at boot, but anyway... Then the app runs, using that memory, for a multi-hour surgery. The allocation happens once; the inter-node DMA transfers occur dozens or hundreds of times per second. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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