On 2017-09-21 15:51:54 -0500, Jim Van Fleet wrote:
> Not to beat on a dead horse, or anything, but this fix was frowned upon
> because in one environment (one socket) it was 6% down and over 15% up in
> the right environment (two sockets).
> So, why not add a configuration parameter which specifies the number of
> parts? Default is 1 which would be "exactly" the same as no parts and
> hence no degradation in the single socket environment -- and with 2, you
> get some positive performance.
Several reasons:
- You'd either add a bunch of branches into a performance critical parts, or you'd add a compile time flag, which most
peoplewould be unable to toggle.
- It'd be something hard to tune, because even on multi-socket machines it'll be highly load dependant. E.g. workloads
thatlargely are bottlenecked in a single backend / few backends will probably regress as well.
FWIW, you started a new thread with this message, that doesn't seem
helpful?
Greetings,
Andres Freund
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