Scene graph performance
richard.bair at oracle.com
Thu Jul 21 18:17:57 UTC 2016
I think you just nailed it on the head Markus :-).
> On Jul 21, 2016, at 10:56 AM, Markus KARG <markus at headcrashing.eu> wrote:
> The limiting factor is the single-thread architecture of rather all parts of JavaFX. The only real difference you see between machines is not correlating with neither number of CPU cores nor GPU cores, but only with CPU frequency, roughly spoken. Short term fixes will only provide little improvement, by optimizing the critical execution path (i. e. produce hot spot histogram using a profiler), for example improvement clipping, caching, etc. Huge performance optimizations need an architectural change within JavaFX's "scenegraph-to-bitmapframe" (a.k.a. rendering) pipeline to use parallel execution in lots of places. Typical design patterns would be parallel iterations, work-stealing executors, fibers (a.k.a cooperative multi-threading, a.k.a CompletableFuture), and last but not least partitioned rendering (a.k.a tiled rendering).
> I am pretty sure you can add a lot more ideas to the list and produce great performance, scaling linearly with number of CPU cores / GPU cores, but this somes at a cost: Risk to introduce hard to track bugs, and needed manpower.
> If somebody has at least a lot of free spare time, I am pretty sure Kevin could easily provide a huge set of work items in this area. :-)
> -----Original Message-----
> From: openjfx-dev [mailto:openjfx-dev-bounces at openjdk.java.net] On Behalf Of Dr. Michael Paus
> Sent: Donnerstag, 21. Juli 2016 12:07
> To: openjfx-dev at openjdk.java.net
> Subject: Re: Scene graph performance
> Hi Felix,
> I have written various tests like the ones you use in FXMark and I have obtained similar results. I have even tried to substitute 2D shapes by using 3D MeshViews in the hope that this would give better performance but the results were not that good. Of course all this depends on the specific test case but in general I see that a JavaFX application which makes heavy use of graphics animations is completely CPU-bounded.
> The maximum performance is reached when one CPU/Core is at 100%.
> The performance of your graphics hardware seems to be almost irrelevant.
> I could for example run four instances of the same test with almost the same performance at the same time. In this case all 4 cores of my machine were at 100%. This proves that the graphics hardware is not the limiting factor. My machine is a MacBook Pro with Retina graphics and a dedicated NVidia graphics card which is already a couple of years old and certainly not playing in the same league as your high-power card.
> I myself have not yet found a way to really speed up the graphics performance and I am a little bit frustrated because of that. But it is not only the general graphic performance which is a problem. There are also a lot of other pitfalls into which you can stumble and which can bring your animations to a halt or even crash your system. Zooming for example is one of these issues.
> I would like to have some exchange on these issues and how to best address them but my impression so far is that there are only very view people interested in that. (I hope someone can prove me wrong on this :-)
> Am 20.07.16 um 04:14 schrieb Felix Bembrick:
>> Having written and tested FXMark on various platforms and devices, one
>> thing has really struck me as quite "odd".
>> I started work on FXMark as a kind of side project a while ago and, at
>> the time, my machine was powerful but not "super powerful".
>> So when I purchased a new machine with just about the highest specs
>> available including 2 x Xeon CPUs and (especially) 4 x NVIDIA GTX
>> Titan X GPUs in SLI mode, I was naturally expecting to see significant
>> performance improvements when I ran FXMark on this machine.
>> But to my surprise, and disappointment, the scene graph animations ran
>> almost NO faster whatsoever!
>> So then I decided to try FXMark on my wife's entry-level Dell i5 PC
>> with a rudimentary (single) GPU and, guess what - almost the same
>> level of performance (i.e. FPS and smoothness etc.) was achieved on
>> this considerably less powerful machine (in terms of both CPU and GPU).
>> So, it seems there is some kind of "performance wall" that limits the
>> rendering speed of the scene graph (and this is with full speed
>> animations enabled).
>> What is the nature of this "wall"? Is it simply that the rendering
>> pipeline is not making efficient use of the GPU? Is too much being done on the CPU?
>> Whatever the cause, I really think it needs to be addressed.
>> If I can't get better performance out of a machine that scores in the
>> top 0.01% of all machine in the world in the 3DMark Index than an
>> entry level PC, isn't this a MAJOR issue for JavaFX?
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