Re: A reason for testing at fixed number of nodes.
Posted: Fri Nov 06, 2009 9:52 pm
I was not suggesting testing only with fixed number of nodes, but as a check on results from normal testing. The PGO was to get some estimate of how much results could be influenced by optimization effects, e.g if the difference were 10 ELO, then if the difference between two versions is 5 ELO, it could be explained by optimization differences and not any intrinsic difference between the strength of the versions. It makes me wonder if the problem of testing improvements to chess programs is NP complete.bob wrote:The inverse is true. If you slow the program down, but test with fixed nodes, you will have no idea that you have actually _hurt_ performance overall, when you start to test with a clock.jwes wrote:When normal tests show a particular change is not an improvement, there are three possibilities.
1. The change does not make the program better.
2. The change makes the program better but slows the program more than the change is worth.
3. The change makes the program better but some optimization weirdness causes the program to run more slowly.
Tests at fixed number of nodes can separate cases 2 and 3 from case 1 and those case can be saved and tried again later or possibly optimized better.
A related test that would be of interest would be to test a version with PGO against the same version without PGO to get an estimate of the ELO difference that could be caused by optimization weirdness.
Personally, to me, it makes no sense to test in a different way from the way the program is used. Would you test a drag racer on a chassis dyno only? More horsepower means more speed, right? What about traction? Does that extra weight on the front hurt weight transfer?
I want to test like I am going to run. And currently, all chess games use time, not nodes.
I don't follow PGO at all. That only affects speed, never the nodes searched for a given depth. So how will using PGO or not influence the final game results since you will be searching the same number of nodes, where any optimizations are absolutely irrelevant since time doesn't count?