POINTS PShape performance is drastically worse in 4.0.b3

[cacheflowe]

With the latest core.jar, a technique I've been using for GPGPU particles is now incredibly slow. I'm guessing it's something to do with changes to the way that geometry is cached in the latest update. I've gone from 60fps with lots of headroom to draw more graphics, down to 10fps. I've tested with POINTS geometry, but I'm guessing other types of geometry might be impacted.

Steps to Reproduce

Run this code in the latest version of Processing (4.0.b3), and then run it in an older version - even 3.5.4 works great. This makes a PShape with about 1 million points, which used to run great on a decent GPU. Now it is very slow.

PShape s;

void settings() {
  size(800, 800, P3D);
}

void setup() {
  s = buildPointsShape(1024, 1024);
}

PShape buildPointsShape(int w, int h) {
    int vertices = w * h;
    s = createShape();
    s.beginShape(POINTS);
    for (int i = 0; i < vertices; i++) {
      s.stroke(255);
      s.vertex(random(-256, 256), random(-256, 256), random(-256, 256));
    }
    s.endShape();
    return s;
}

void draw() {
  background(0);
  text(frameRate, 30, 30);
  translate(width/2, height/2);
  rotateY(frameCount/20.);
  shape(s);
}

Your Environment

• Processing version: 4.0.b3
• Operating System and OS version: Windows 11, NVIDIA RTX3080

[codeanticode]

Oops, sounds like a performance-impacting regression :-( I will look into it, so can be fixed in the next beta.

[codeanticode]

@cacheflowe Cannot reproduce the issue using the code you posted, it runs at 60 fps on my computer. Do you have any other example showing a slowdown in PShape?

[cacheflowe]

@codeanticode Thanks for looking at this. I've tried a ton of different settings on the video card and Windows, and I'm consistently getting 10fps on this code with 4.0.3b, but 60fps on any version beforehand. If I switch from POINTS to LINES in the code above, it goes back up to 60fps, so maybe it has something to do specifically with POINTS. If I use TRIANGLES, I get 33fps in older versions, but 22fps in 4.0.3b, so triangles seem impacted as well.

I've been testing all of the Processing examples, as well as my own apps, and most code seems fine at first glance. But...

I did find one other app that went from 60fps down to 50 when I switch core.jar to 4.0.3b. This app of mine has a noticeable slowdown - it regrettably has lots of dependencies on my little framework. In short, I'm creating around 60k cubes in a PShape group, giving each one sub-shape attributes that let me move/rotate/scale them in a vertex shader. I'm using createShape(BOX, w, h, d) to create the sub shapes. I'm not sure what the commonality is here, but I do think something has changed in core.jar that makes certain geometry slower. Though it's only noticeable when working with pretty high vertex counts on my machine.

I'll try to find more clues here - let me know if you think of anything I could try. And thank you!

[codeanticode]

hmm maybe it's platform-dependent? The big change introduced in b3 was buffer object streaming in PShape (#196), which should not result in any performance difference in all normal uses of PShape, and speed things up when modifying PShape objects after creation. But maybe there is some driver issue that is affecting streaming on windows? I'd need to run more tests, and I wonder if you have access to other systems to check if the issue happens on all of them.

[cacheflowe]

I've been trying to find a way to do GPU profiling but haven't found a good way to do that yet. I've also changed every NVIDIA setting but nothing has helped. 4.0.4b still exhibits the same slowdown for me.

[codeanticode]

Really strange, I run some tests on a windows laptop and saw no difference pre and after b3, although it was not an nvidia-based computer. I haven't seen anybody else reporting PShape slowdowns so I'm still guessing is a system-specific issue. Have you a the chance to try on a different computer?

[codeanticode]

@cacheflowe do you have any other info on this issue? were you able to run the latest beta on another computer so see if the slowdown still happens?

[cacheflowe]

@codeanticode I just pulled out an older Alienware mini PC with a GTX 860M GPU, and tried this code with 4.0.2b, 4.0.3b, and 4.0.6b. I tested the same code on my newer RTX 3080 on those same Processing versions. Unfortunately, there is consistency with my NVIDIA GPUs:

• 4.0.2b and prior, this sketch runs at 60fps, even on the old machine
• 4.0.3b and 4.0.6b the sketch runs around 10fps on both machines

I'm happy to test this more, but these are the only machines I have easy access to right now.

[codeanticode]

Ok thanks for the additional testing, I will look into this further.

[benfry]

@codeanticode Safe to close after #432?

[codeanticode]

@benfry I think so but let's wait for confirmation from @cacheflowe. Looks like this issue is affected by the implementation of the gl drivers on each platform.

@cacheflowe Let us know if performance is restored in beta7. There are a couple of internal parameters you can play with in case is still lower, and would be help us understand what might still be causing trouble.

For instance, if you do:

void setup() {
  PGL.USE_BUFFER_OBJECT_STREAMING_IN_RETAINED_MODE = false;
  s = buildPointsShape(1800, 1700);
}

all the buffer object streaming optimizations introduced in beta3 are disabled, so you should get exactly the same performance as before. You can also play with the buffer access parameter (when buffer object streaming is enabled), for example:

void setup() {
  PGL.glBufferAccess = PGL.READ_WRITE;
  s = buildPointsShape(1800, 1700);
}

PGL.READ_WRITE is the new default, which should solve the performance issue, but you can also try PGL.WRITE_ONLY (the previous default) and PGL.READ_ONLY.

@benfry I will create a new PR so the naming of these debug parameters is more consistent.

[cacheflowe]

Performance is restored in beta 7!

A few notes:

• PGL.glBufferAccess = PGL.WRITE_ONLY brings it back down to very slow performance.
• PGL.glBufferAccess = PGL.READ_ONLY makes the shape disappear, but fps is still good :-D
• PGL.USE_BUFFER_OBJECT_STREAMING_IN_RETAINED_MODE = true seems to cause an interval where the performance dips about every couple of seconds. It feels like a GC pause on the main thread. This seems not-good.
• PGL.USE_BUFFER_OBJECT_STREAMING_IN_RETAINED_MODE = false appears to be the default behavior. I'm seeing several of the GC-like pauses (dips in FPS), but after 3-10 of those, it stops and stays at a nice smooth 60fps. It seems like something's getting gradually cached? Is that possible?

Anyway, THANK YOU for the solutions 🙇

[benfry]

Woohoo! Closing.

[codeanticode]

@cacheflowe glad it works, and thanks for testing the different combinations of buffer parameters. Right now, seems like streaming enabled and write-only is the way to go in most situations. Please notice that in beta8 those PGL parameters will be renamed according to the changes in this PR.

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