Re: BGWriter latch, power saving

On 4 January 2012 07:24, Heikki Linnakangas
<heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
> I think SetBufferCommitInfoNeedsSave() needs the same treatment as
> MarkBufferDirty(). And it would probably be good to only set the latch if
> the buffer wasn't dirty already. Setting a latch that's already set is fast,
> but surely it's even faster to not even try.

That seems reasonable. Revised patch is attached.

> Yeah, I'd like to see a micro-benchmark of a worst-case scenario. I'm a bit
> worried about the impact on systems with a lot of CPUs. If you have a lot of
> CPUs writing to the same cache line that contains the latch's flag, that
> might get expensive.

Also reasonable, but I don't think that I'll get around to it until
after the final commitfest deadline.

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