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.
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This archive was generated by hypermail 2b29 : Sun Dec 31 2000 - 21:00:07 EST