Date: Tue, 31 Oct 2000 08:08:28 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Peter Dufault <dufault@hda.com> Cc: Terry Lambert <tlambert@primenet.com>, Ryan Thompson <ryan@sasknow.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: Filesystem holes Message-ID: <200010311608.e9VG8SU18725@earth.backplane.com> References: <200010311235.HAA31834@hda.hda.com>
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: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,
If you can fit the whole thing into a process's VM space, then you
can certainly use mmap(...MAP_ANON...) combined with madvise(... MADV_FREE)
to implement a sparse memory object.
There was talk a while ago about feeding MADV_FREE through to the
filesystem layer. I was under the impression that SUN does that, does
anyone know?
-Matt
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