On 2018-03-06 12:16:01 -0800, Andres Freund wrote: > > I ran some performance assessments: > > > > merge base (0b1d1a038babff4aadf0862c28e7b667f1b12a30) > > > > make installcheck 3.14s user 3.34s system 17% cpu 37.954 total > > > > jit branch default settings > > > > make installcheck 3.17s user 3.30s system 13% cpu 46.596 total > > > > jit_above_cost=0 > > > > make installcheck 3.30s user 3.53s system 5% cpu 1:59.89 total > > > > jit_optimize_above_cost=0 (and jit_above_cost=0) > > > > make installcheck 3.44s user 3.76s system 1% cpu 8:12.42 total > > > > jit_inline_above_cost=0 (and jit_above_cost=0) > > > > make installcheck 3.32s user 3.62s system 2% cpu 5:35.58 total > > > > One can see the CPU savings quite nicely. > > I'm not quite sure what you mean by that. > > > > One obvious problem is that with the default settings, the test suite > > run gets about 15% slower. (These figures are reproducible over several > > runs.) Is there some debugging stuff turned on that would explain this? > > Or would just loading the jit module in each session cause this? > > I suspect it's loading the module.
There's also another issue: For a lot queries in the tests the stats are way way way off because the relevant tables have never been analyzed. There's a few cases where costs are off by like 5-7 orders of magnitude... Greetings, Andres Freund