Re: Posix Shared Mem patch

On Tuesday, July 03, 2012 05:41:09 PM Tom Lane wrote:
> Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> > Btw, RhodiumToad/Andrew Gierth on irc talked about a reason why sysv
> > shared memory might be advantageous on some platforms. E.g. on freebsd
> > there is the kern.ipc.shm_use_phys setting which prevents paging out
> > shared memory and also seems to make tlb translation cheaper. There does
> > not seem to exist an alternative for anonymous mmap.
> Isn't that mlock()?
Similar at least yes. I think it might also make the virtual/physical
translation more direct but that ist just the impression of a very short
search.

> > So maybe we should make that a config option?
> I'd really rather not. If we're going to go in this direction, we
> should just go there.
I don't really care, just wanted to bring up that at least one experienced
user would be disappointed ;). As the old implementation needs to stay around
for EXEC_BACKEND anyway, the price doesn't seem to be too high.

Andres
--
Andres Freund http://www.2ndQuadrant.com/
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