The perf diff is more that what i was expected :) Looks good to me !
Rémi ----- Mail original ----- > De: "Claes Redestad" <claes.redes...@oracle.com> > À: "Remi Forax" <fo...@univ-mlv.fr> > Cc: "core-libs-dev" <core-libs-dev@openjdk.java.net> > Envoyé: Mercredi 2 Janvier 2019 21:32:09 > Objet: Re: RFR: 8215412: Optimize PrintStream.println methods > Hi again, > > as expected not much of a difference on the test I was using (a small > cost on the startup/warmup numbers due replacing a boolean check with a > method call), but on a test that adds in a few extended PrintStreams > and mixes those with use of System.out I can get a ~3-4% statistical > improvement with your idea - so I think it's better to peel off > the PrintStream.class check like this: > > http://cr.openjdk.java.net/~redestad/8215412/jdk.03/ > > Thanks! > > /Claes > > On 2019-01-02 13:29, Claes Redestad wrote: >> Hi Rémi, >> >> >> On 2019-01-02 13:05, Remi Forax wrote: >>> Hi Claes, >>> did you try instead of having a field 'internal' to inline the class >>> check (this.getClass() == PrintStream.class) at every call site you >>> are reading that field ? >>> >>> for a method like println(), the VM has to do a class check (if CHA is >>> defeated) before entering the method println so the JIT might be able >>> to remove the check this.getClass() == PrintStream.class because it >>> already know at that point that the current class is PrintStream. >> >> interesting idea - I'll try it out. I don't expect it to make much of a >> difference in my current (trivial) tests, but perhaps in a slightly more >> contrived setup. >> >> happy new year! >> > > /Claes
