Date: Tue, 31 Oct 2000 07:34:16 -0500 (EST) From: Peter Dufault <dufault@hda.com> To: Matt Dillon <dillon@earth.backplane.com> Cc: Terry Lambert <tlambert@primenet.com>, Ryan Thompson <ryan@sasknow.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: Filesystem holes Message-ID: <200010311235.HAA31834@hda.hda.com> In-Reply-To: <200010310907.e9V97mk17233@earth.backplane.com> from Matt Dillon at "Oct 31, 2000 01:07:48 am"
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> ... 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 (dufault@hda.com) Realtime development, Machine control, HD Associates, Inc. Fail-Safe systems, Agency approval To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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