Re: [HACKERS] Changing the default configuration

On Thu, 13 Feb 2003, Bruce Momjian wrote:

> To auto-tune, you would need to monitor swap usage and other stuff that
> may vary too much based on load from other systems.  Only the admin
> knows how to answer some of those questions.

No, to "auto-tune" many parameters that currently require manual
configuration, you merely need to change things so that you work with
the OS, rather than beside it.

There are a lot of things we could mmap that would remove the need for
tuning certain things altogether. The buffer cache is the biggest one;
mmaping that would let the OS take care of it all, and a few hundred KB
of shared memory would be all postgres would need. (Or none at all, if
you used mmap'd memory regions where for that part of your IPC as well.)

You could probably also make sort_mem need a lot less tuning if you
sorted in mmap'd memory and let the OS deal with paging only when and
if it needed it (as well as asking the OS not to page memory you're
randomly accessing, since it really destroys your peformance when you do
that).

I'm not sure if you could get rid of semaphores or not, but if you
could somehow do that, that would be another limited resource that you
wouldn't have to deal with.

cjs
--
Curt Sampson  <cjs@cynic.net>   +81 90 7737 2974   http://www.netbsd.org
    Don't you know, in this new Dark Age, we're all light.  --XTC