> ... Sparse matrixes are the big math problem
> that benefit, but only because the solution to a sparse matrix problem
> is not even close to random so the sparse matrix winds up still being
> sparse all the way to the end of the solution.
I use them for bus simulations, which also are permanently sparse.
It would be nice to free up the regions when I "remove" a virtual
board, but in a check through POSIX I could find nothing defined to
behave that way either for mapped files or mapped memory objects.
Also, a write from any process would repopulate the region which
I really wouldn't want but I don't see that level of control
over mapping between unrelated processes (Now I start thinking
about MAPFIXED to a specified virtual address and implementing funny
tricks but I don't have time to work on that).
In my case I'd be better off with shared memory objects that aren't
persistent but appear in the name space so that I don't accidentally
start copying a virtual bus file when the programs exit improperly.
In the sparse matrix calculations with no checkpointing or need to appear
in a name space I'd think the best thing would be to use VM with the matrix
initially mapped to a copy on write zero page. I guess you can't
do that without mmap because of swap allocation.
Peter
--
Peter Dufault ([EMAIL PROTECTED]) Realtime development, Machine control,
HD Associates, Inc. Fail-Safe systems, Agency approval
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