On Thursday, June 28, 2012 08:00:06 PM Tom Lane wrote: > Andres Freund <and...@2ndquadrant.com> writes: > > On Thursday, June 28, 2012 07:43:16 PM Tom Lane wrote: > >> I think it *would* be a good idea to mlock if we could. Setting shmem > >> large enough that it swaps has always been horrible for performance, > >> and in sysv-land there's no way to prevent that. But we can't error > >> out on permissions failure. > > > > Its also a very good method to get into hard to diagnose OOM situations > > though. Unless the machine is setup very careful and only runs postgres I > > don't think its acceptable to do that. > > Well, the permissions angle is actually a good thing here. There is > pretty much no risk of the mlock succeeding on a box that hasn't been > specially configured --- and, in most cases, I think you'd need root > cooperation to raise postgres' RLIMIT_MEMLOCK. So I think we could try > to mlock without having any effect for 99% of users. The 1% who are > smart enough to raise the rlimit to something suitable would get better, > or at least more predictable, performance. The heightened limit might just as well target at another application and be setup a bit to widely. I agree that it is useful, but I think it requires its own setting, defaulting to off. Especially as there are no experiences with running a larger pg instance that way.
Greetings, Andres, for once the conservative one, Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
