Re: Interruptible sleeps (was Re: CommitFest 2009-07: Yay, Kevin! Thanks, reviewers!)

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Fri, Aug 27, 2010 at 5:54 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
>> The way the background writer wakes up periodically to absorb fsync requests
>> is already way too infrequent on a busy system.

> Maybe instead of a fixed-duration sleep we could wake it up when it
> needs to do something.

*Any* fixed delay is going to be too long for some people and not long
enough for others; and the very same system might fall into both
categories at different times of day. I don't think "make
bgwriter_delay customizable" is an adequate answer. We've put up with
that so far because it wasn't possible to do better given the
infrastructure we had for waiting; but if we're going to try to improve
the infrastructure, we should have the ambition of getting rid of this
type of problem.

regards, tom lane