986862 - Nightly on OSX: extremely unresponsive input/UI in WebGL demo with several hundred draw calls

Status: NEW

(Core :: Graphics: CanvasWebGL, defect, P3)

Description

[Andre Weissflog]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:31.0) Gecko/20100101 Firefox/31.0 (Beta/Release)
Build ID: 20140322030204

Steps to reproduce:

- in OSX in FF Nightly 31.0a1 (2014-03-22) go to http://www.flohofwoe.net/demos/dragons_asmjs.html
- note how the demo responds smoothly to mouse input (hold left mouse button and move mouse to rotate the view)
- now add more dragons by pressing the Up key about 10x
- note how the frame rate fluctuates wildly and there's a big input lag



Expected results:

While the demo should drop in frame rate when more dragons are added, the frame rate shouldn't fluctuate, and there should be no input lag.

There was a similar bug a while ago which felt almost exactly the same: https://bugzilla.mozilla.org/show_bug.cgi?id=864053

My system: MacBookPro 13", OSX 10.9.2, GPU is Intel HD4000

Comment 1

[Paul Silaghi, QA [:pauly]]

Tested on nightly 31.0a1 (2014-04-01), mini Mac OS X 10.9, AMD Radeon HD 6630 M 256, Intel Core i5-2520M 2.50GHz.
1 dragon - 60 fps
x10 dragons - 25 fps
x15 dragons - 13 fps
For me, the lag is not so big as you said, I would say it's appropriate. I think a lower performance is expected when increasing the number of dragons.

Comment 2

[Andre Weissflog]

Yes, those frame rate numbers look alright, but how does it feel when rotating the camera with mouse or trackpad, do you have big (1..2 seconds) and really irregular input lag? On my laptop the displayed frame rate looks stable too (meaning the frame loop seems to be alright), but trying to manipulate the camera is extremely sluggish, and the rest of the UI also seems to be affected.

Comment 3

[Kelsey Gilbert [:jgilbert]]

We wait for frame completion before compositing. (In the GL driver on some mac, and on the main thread elsewhere)
This report sounds like a manifestation of why this is bad.

We're pretty sure we don't want to do this. Instead, we want to poll for completion.

Comment 4

[Andre Weissflog]

On my machine it's a big difference between current Nightly and FF29 though, FF29 feels a lot smoother (although I think 27 was even better), and Chrome Canary feels smoother then FF29. I don't remember Chrome "feeling smoother" on my config, since in the past it was always JS performance that made the difference when many dragons are rendered, now it seems like the WebGL implementation somehow interferes. Yeah I know, "feeling smoother" isn't exactly a very objective measurement ;)

Comment 5

[u480271]

I wonder if this is related to bug 991434.