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On Fri, Jun 04, 2004 at 10:07:41AM +0200, Frank Kardel wrote:
> Hi *,
>=20
> just a few thoughs with respect to vm page usage, i haven't checked wheth=
er
> this has been discussed before, if it has: I am sorry.
>=20
> When writing a large backup data is copied sequentially from a file to=20
> some place else.
> The vm system seemingly keeps these pages around just like any other=20
> file pages. Thus there is a constant need for fresh pages and thus all
> other file pages are pushed out in favor of the pages for the sequential
> file copy.

I don't know whether this actually works sufficiently well with the=20
current VM implementation and pmaps, but...

your backup program should mmap() the files to read and
madvise(addr, len, MADV_SEQUENTIAL) them.

(Unless you need madvise(addr, len, MADV_RANDOM), of course.)

Regards,
	-is

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