Re: vfork: out of memory, when there's plenty of swap free

Linus Torvalds (torvalds@transmeta.com)
Sun, 14 Mar 1999 10:28:07 -0800 (PST)


On Sun, 14 Mar 1999, Andrea Arcangeli wrote:
>
> On Sat, 13 Mar 1999, Linus Torvalds wrote:
>
> >It might certainly be an option to allocate inodes in bigger chunks at a
> >time. That would at least make the problem become less.
>
> It would make the problem to go away completly according to me.

For inodes, yes.

For other things, no.

And it makes allocating inode pages a riskier thing - although for inodes
we almost always do have the option of just trying to free up something
else, so there a "soft" allocator may well be completely acceptable.

> We simply need to alloc 32pages at time instead of 1 page at time.

I don't thik we want to go quite that aggressively up to 32 pages, it's
just too likely to fail. Going to 2 or 4 is probably fine (just 2 pages
is enough to guarantee that there is no 2-page fragmentation, which is all
that forking cares about, and is safer if you worry about making sure you
can sometimes get new inodes).

Want to try it and see? It should be trivial to change the inode code to
allocate 2 or four pages at a time (two constants need to change).

Linus

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