Re: Automatic adjustment of bgwriter_lru_maxpages

On Mon, 14 May 2007, Heikki Linnakangas wrote:

> If it's safe to set it high, let's default it to infinity.

The maximum right now is 1000, and that would be a reasonable new default.
You really don't to write more than 1000 per interval anyway without
taking a break for checkpoints; the more writes you do at once, the higher
the chances are you'll have the whole thing stall because the OS makes you
wait for a write (this is not a theoretical comment; I've watched it
happen when I try to get the BGW doing too much).

If someone has so much activity that they're allocating more than that
during a period, they should shrink the delay instead.  The kinds of
systems where 1000 isn't high enough for bgwriter_lru_maxpages are going
to be compelled to adjust these parameters anyway for good performance.

--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD