[OpenJDK 2D-Dev] Review Reqeust for Bug 100068 - SunGraphics2D exposes a reference to itself while non fully initialised

[Jim Graham]

It's odd that J2DBench showed a difference since nothing you did should 
have affected those benchmarks.  I don't think it has any benchmark 
which shows the impact of a pipeline validation, so your standalone test 
is the only one that I think addresses the issue.

Rather than setting up a machine for a 72 hour run (not sure a run of 
what, though - J2DBench?), I'd rather see either trying to do the check 
with a virtual method call (Pipe.needsLoops) or just going back to the 
old style of initializing them in the validation branches that we know 
need them and we can revisit this mechanism some other time when we have 
the time to really figure out how to make it cheap.  In particular, I 
have some ideas for how to make validation incredibly cheap at the cost 
of a few K of lookup tables per SurfaceData, but I think the scale of 
that is beyond us for now...

			...jim

Mario Torre wrote:
> Il 15/07/2009 23:41, Jim Graham ha scritto:
>> Numbers that small aren't statistically significant.  Our J2DBench
>> benchmark calibrates each test to run a number of iterations that result
>> in at least 2.5 seconds of run time. Try upping your loop iterations by
>> a factor of 100 and you'll get numbers with better accuracy and
>> precision...
>>
>> ...jim
> 
> Hi Jim,
> 
> I multiplied the small test numbers by 100 and this is the result:
> 
> Patched JDK:
> 
> warmed up run time in ms: 3226
> total time in ms: 9586
> 
> Clean JDK:
> 
> warmed up run time in ms: 3039
> total time in ms: 9172
> 
> I also run the more meaningful Java2DBench. I had no time to run an 
> extensive benchmark, and only limited to what I think it's the very bare 
> minimum:
> 
> http://cr.openjdk.java.net/~neugens/100068/comparision-100068-0.1/Summary_Report.html 
> 
> 
> So, looks like this approach has indeed an impact, although is well 
> within 10%.
> 
> Should I try the other approaches? I hardly see how a method call can be 
> faster than an instanceof, but maybe I miss something obvious.
> 
> If you want, I can try to setup a machine at work to run a full 72 hour 
> test, but this will take some time ( > 72*2 hours :).
> 
> Cheers,
> Mario