Re: Report: Linux huge pages with Postgres

Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> On Sun, 2010-11-28 at 12:04 -0500, Tom Lane wrote:
>> There's no exposed API for causing a process's regular memory to become
>> hugepages.

> We could make all the palloc stuff into shared memory also ("private"
> shared memory that is). We're not likely to run out of 64-bit memory
> addresses any time soon.

Mph. It's still not going to work well enough to be useful, because the
kernel design for hugepages assumes a pretty static number of them.
That maps well to our use of shared memory, not at all well to process
local memory.

> Sure, but 4MB of memory is enough to require 1000 TLB entries, which is
> more than enough to blow the TLB even on a Nehalem.

That can't possibly be right. I'm sure the chip designers have heard of
programs using more than 4MB.

regards, tom lane