Re: effect of JIT tuple deform?

Hi,

On 2018-06-24 22:32:07 +0200, Dmitry Dolgov wrote:
> `perf diff` indeed shows that in the first case (with the 4M rows dataset) the
> jitted version has some noticeable delta for one call, and unfortunately so far
> I couldn't figure out which one exactly because of JIT (btw, who can explain
> how to see a correct full `perf report` in this case? Somehow `perf
> inject --jit -o
> perf.data.jitted` and jit_profiling_support didn't help).

jit_profiling_support currently requires a patch (that I'm about to
merge into their trunk) in LLVM. I've posted it a couple times to the
list.

> But since on the bigger dataset I've got expected results, maybe it's just a
> sign that JIT kicks in too early in this case and what's necessary is to adjust
> jit_above_cost/jit_optimize_above_cost/jit_inline_above_cost?

Yea, that's very likely the problem. I wonder if we should multiply the
cost w/ the number of targeted workers to reduce problems with
parallelism...

Greetings,

Andres Freund