Re: [RFC][PATCH 0/3] beat kswapd with the proverbial clue-bat

[Nick Piggin]

Nick Piggin wrote:
> David S. Miller wrote:
>
> > On Sun, 05 Sep 2004 15:44:18 +1000
> > Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:
> >
> >
> > > So my solution? Just teach kswapd and the watermark code about higher
> > > order allocations in a fairly simple way. If pages_low is (say), 1024KB,
> > > we now also require 512KB of order-1 and above pages, 256K of order-2
> > > and up, 128K of order 3, etc. (perhaps we should stop at about order-3?)
> >
> >
> >
> > Whether to stop at order 3 is indeed an interesting question.
> >
> > The reality is that the high-order allocations come mostly from folks
> > using jumbo 9K MTUs on gigabit and faster technologies.  On x86, an
> > order 2 would cover those packet allocations, but on sparc64 for example
> > order 1 would be enough, whereas on a 2K PAGE_SIZE system order 3 would
> > be necessary.
>
> Yeah I see.

Hmm, and the crowning argument for not stopping at order 3 is that if we
never use higher order allocations, nothing will care about their watermarks
anyway. I think I had myself confused when that question in the first place.

So yeah, stopping at a fixed number isn't required, and as you say it keeps
things general and special cases minimal.
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