Hi Tobias, Just to add to the cheer. It is not everyday that one sees 97% improvements on performance. I understand this is preliminary. Looking forward to seeing it applied in real world code.
Albert > On Sep 23, 2014, at 7:02 PM, Tobias Pietzsch <pietz...@mpi-cbg.de> wrote: > > Hi guys, > > As a weekend project I have started to look into bytecode modification using > the wonderful ASM library (http://asm.ow2.org). > I have cleaned up what I have played with and put it on github > https://github.com/tpietzsch/neon. > > It tackles a long-standing imglib obstacle, namely megamorphic call-sites in > certain methods, where the JIT fails to recognise that the runtime target of > the polymorphic changes between calls to a method but doesn’t change in the > hot inner loop of the method during a single call. I have been talking about > ideas to address this for quite some time, most recently here > https://github.com/imglib/imglib/issues/71#issuecomment-51227237. Now I went > ahead and actually tried to do something about it. > > I have applied it to an example in imglib, which is described below. But for > anyone not familiar with this particular issue (which is everyone except > Christian probably) there > is an illustrative example with explanations in the README on github > https://github.com/tpietzsch/neon/blob/master/README.md. > This does not involve imglib at all and is a clear illustration of the > problem (and my solution). > > I’m quite happy with how it turned out so far. It certainly has to be applied > with care, but I think this can be potentially huge for imglib2. It might > open up new possibilities that we have shied away from because of performance > reasons, such as internal iteration for IterableIntervals. > > Curtis, Johannes and Christian, I would also be interested what you think of > this as a potential tool for imagej-ops. > I think it is orthogonal to what you do with compile-time code generation > currently and therefore might complement it nicely. > > I hope you have a look and tell me what you think. > I would be especially interested in whether you can think of optimization > idioms besides the @Instantiate @ByTypeOf that is implemented right now. > It would be cool if we discuss this in the upcoming imglib hackathon. > > Okay, everybody except Christian might as well stop reading now. > > all the best, > Tobias > > > > > > PS: the imglib stuff... > > For the imglib issue https://github.com/imglib/imglib/issues/71, we played > with ways of iterating pixels which can be optimized for certain subintervals > of larger images. > The optimizations work out nicely when done on their own, but everything > really breaks down when a single method is used with differnent Cursor > incarnations. > This is actually already a potential problem in standard imglib, when Cursors > from different Img types are uses in a single method. But adding the new > optimized versions > only made it more probable that the problem actually occurs. > > Here is numbers from a recent test, at a stage where 4 different kinds of > cursors are in play: > > normal cursor | array img > walk through a subinterval > | Unoptimized | Optimized | Speedup Time | Speedup % | > Best | 566 | 371 | 195ms | 34.4% | > > localizing cursor | array img > walk through a subinterval > | Unoptimized | Optimized | Speedup Time | Speedup % | > Best | 907 | 584 | 323ms | 35.6% | > > normal cursor | planar img > walk through a subinterval > | Unoptimized | Optimized | Speedup Time | Speedup % | > Best | 562 | 373 | 189ms | 33.6% | > > localizing cursor | planar img > walk through a subinterval > | Unoptimized | Optimized | Speedup Time | Speedup % | > Best | 928 | 611 | 317ms | 34.1% | > > > With the neon java agent this improves to: > > normal cursor | array img > walk through a subinterval > | Unoptimized | Optimized | Speedup Time | Speedup % | > Best | 153 | 8 | 145ms | 94.7% | > > localizing cursor | array img > walk through a subinterval > | Unoptimized | Optimized | Speedup Time | Speedup % | > Best | 235 | 200 | 35ms | 14.8% | > > normal cursor | planar img > walk through a subinterval > | Unoptimized | Optimized | Speedup Time | Speedup % | > Best | 128 | 8 | 120ms | 93.7% | > > localizing cursor | planar img > walk through a subinterval > | Unoptimized | Optimized | Speedup Time | Speedup % | > Best | 217 | 208 | 9ms | 4.1% | > > > A speedup of factor ~4 to ~40 can be observed. > These two runs were made with exactly the same code, but for the second one, > the program was run with the option > java -javaagent:/path/to/neon-1.0.0-SNAPSHOT.jar … > > I just pushed the example to > https://github.com/imglib/imglib/commit/a9b70d923e9a84c4055acae96f71d05ca4a26344 > _______________________________________________ ImageJ-devel mailing list ImageJ-devel@imagej.net http://imagej.net/mailman/listinfo/imagej-devel
