Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19

Nick Piggin
2005-10-31T23:59:03Z

Martin J. Bligh wrote:
> --On Monday, October 31, 2005 11:24:09 -0800 Andrew Morton <akpm@osdl.org> wrote:

>>I suspect this would all be a non-issue if the net drivers were using
>>__GFP_NOWARN ;)
>
>
> We still need to allocate them, even if it's GFP_KERNEL. As memory gets
> larger and larger, and we have no targetted reclaim, we'll have to blow
> away more and more stuff at random before we happen to get contiguous
> free areas. Just statistics aren't in your favour ... Getting 4 contig
> pages on a 1GB desktop is much harder than on a 128MB machine.
>

However, these allocations are not of the "easy to reclaim" type, in
which case they just use the regular fragmented-to-shit areas. If no
contiguous pages are available from there, then an easy-reclaim area
needs to be stolen, right?

In which case I don't see why these patches don't have similar long
term failure cases if there is strong demand for higher order
allocations. Prolong things a bit, perhaps, but...

> Is not going to get better as time goes on ;-) Yeah, yeah, I know, you
> want recreates, numbers, etc. Not the easiest thing to reproduce in a
> short-term consistent manner though.
>

Regardless, I think we need to continue our steady move away from
higher order allocation requirements.

--
SUSE Labs, Novell Inc.

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