Re: Reducing power consumption on idle servers

On Thu, 24 Mar 2022 at 15:39, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Thu, Mar 24, 2022 at 6:59 AM Simon Riggs
> <simon(dot)riggs(at)enterprisedb(dot)com> wrote:
> > The proposals of this patch are the following, each of which can be
> > independently accepted/rejected:
> > 1. fix the sleep pattern of bgwriter, walwriter and logical worker
> > (directly affects powersave)
> > 2. deprecate promote_trigger_file, which then allows us to fix the
> > sleep for startup process (directly affects powersave)
> > 3. treat hibernation in all procs the same, for simplicity, and to
> > make sure we don't forget one later
> > 4. provide a design pattern for background worker extensions to
> > follow, so as to encourage powersaving
>
> Unfortunately, the patch isn't split in a way that corresponds to this
> division. I think I'm +1 on change #2 -- deprecating
> promote_trigger_file seems like a good idea to me independently of any
> power-saving considerations. But I'm not sure that I am on board with
> any of the other changes.

OK, so change (2) is good. Separate patch attached.

> I do agree with the basic goal of trying to
> reduce unnecessary wakeups, but I think the rest of the patch is
> taking a bit of a one-size-fits-all approach where I think that we
> might want to be more nuanced. I think there are a couple of different
> kinds of cases here.

OK, so you disagree with (3) and probably (4). No problem.

What about (1)? That directly affects the powersave capability. I
didn't read anything specific to that.

If we don't fix (1) as well, the changes for startup and walreceiver
will be ineffective for powersaving.

What changes will be acceptable for bgwriter, walwriter and logical worker?

--
Simon Riggs http://www.EnterpriseDB.com/