Re: Fixed xloginsert_locks for 9.4

On 2014-10-03 10:07:39 -0400, Gregory Smith wrote:
> On 10/3/14, 8:26 AM, Andres Freund wrote:
> >#define NUM_XLOGINSERT_LOCKS 1
> >tps = 52.711939 (including connections establishing)
> >#define NUM_XLOGINSERT_LOCKS 8
> >tps = 286.496054 (including connections establishing)
> >#define NUM_XLOGINSERT_LOCKS 16
> >tps = 346.113313 (including connections establishing)
> >#define NUM_XLOGINSERT_LOCKS 24
> >tps = 363.242111 (including connections establishing)
>
> Just to clarify: that 10% number I threw out was meant as a rough estimate
> for a system with the default configuration, which is all that I tested. It
> seemed like people would likely need to tune all the usual things like
> checkpoint_segments, shared_buffers, etc. as well before seeing much better.
> You did all that, and sure enough the gain went up; thanks for confirming my
> guess.
>
> I still don't think that means this needs a GUC for 9.4. Look at that jump
> from 1 to 8. The low-hanging fruit here hasn't just been knocked off. It's
> been blended into a frozen drink, poured into a glass, and had a little
> paper umbrella put on top. I think that's enough for 9.4. But, yes, let's
> see if we can add delivery to the side of the pool in the next version too.

So 25% performance on a relatively small machine improvements aren't
worth a GUC? That are likely to be larger on a bigger machine?

I utterly fail to see why that's a service to our users.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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