Re: Sub-millisecond [autovacuum_]vacuum_cost_delay broken

Thomas Munro <thomas(dot)munro(at)gmail(dot)com> writes:
> OK. One idea is to provide a WaitLatchUsec(), which is just some
> cross platform donkeywork that I think I know how to type in, and it
> would have to round up on poll() and Windows builds. Then we could
> either also provide WaitEventSetResolution() that returns 1000 or 1
> depending on availability of 1us waits so that we could round
> appropriately and then track residual, but beyond that let the user
> worry about inaccuracies and overheads (as mentioned in the
> documentation),

... so we'd still need to have the residual-sleep-time logic?

> or we could start consulting the clock and tracking
> our actual sleep time and true residual over time (maybe that's what
> "closed-loop control" means?).

Yeah, I was hand-waving about trying to measure our actual sleep times.
On reflection I doubt it's a great idea. It'll add overhead and there's
still a question of whether measurement noise would accumulate.

regards, tom lane