Big physically contiguous mbuf clusters

[Adrian Chadd]

Hi,

On 29 January 2014 10:54, Garrett Wollman <wollman at csail.mit.edu> wrote:
> Resolved: that mbuf clusters longer than one page ought not be
> supported.  There is too much physical-memory fragmentation for them
> to be of use on a moderately active server.  9k mbufs are especially
> bad, since in the fragmented case they waste 3k per allocation.

I've been wondering whether it'd be feasible to teach the physical
memory allocator about >page sized allocations and to create zones of
slightly more physically contiguous memory.

For servers with lots of memory we could then keep these around and
only dip into them for temporary allocations (eg not VM pages that may
be held for some unknown amount of time.)

Question is - can we enforce that kind of behaviour?



-a