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Re: [Public WebGL] EXT_disjoint_timer_query disabled



Thanks for your input.

From issue 823863:
> Until the extension can be re-enabled globally in Issue 820891,

The intent is to re-enable it for all users once we can.

On Wed, Apr 25, 2018 at 2:15 PM Dr. Helmut Emmelmann <emmel@taccgl.org> wrote:

I am using the timer extension to run webgl on ordinary and especially
landing pages. The idea / goal is to show nearly every visitor a working
web page and most visitors a nice animation within the first few seconds
after navigation.

Quoting Ken Russell <kbr@google.com>:

> In Chrome we don't yet have a way to re-enable this extension easily
(aside
> from --ignore-gpu-blacklist ) but we'll work on adding one in
> http://crbug.com/823863 .
>
> -Ken

When reading http://crbug.com/823863 I got the impression, that it is
planed to reenable EXT_disjoint_timer_query as a private extension for
development only.

I am afraid, however, that this does not cover the use case of detecting
GPU performance of the final client in order to e.g. select among
shaders of different quality and performance.

Often such detection is based on the frame rate (i.e. the frequency the
requestAnimationFrame call back is called). During (or shortly after)
page loading / rendering, however, the frame rate is often slow for
reasons unrelated to webgl (probably because the browsers main threat is
busy). So I use a timer_query, to get more precise timing information.

Now since ext_timer is disabled this leads to the problem that I can´t
find out if the frame rate is slow because of a slow GPU or because of
the page load and so on most devices animations start up with low
quality and only later on, once the frame rate stabelizes, play at
higher quality, a process, that does not look too good (e.g.
http://www.taccgl.org).

I don´t know, what exactly is planned w.r.t. to the ext_timer extension
but if there are problems to reenable it publicly on all devices I
wonder if it is possible to have other feedback mechanisms to help a
webgl application adjusting to the available GPU performance. I could
think of a new extension that returns just the total GPU time needed for
rendering the previous frame, possibly rounded. Or possibly more
detailed information on the reasons why requestAnimationFrame is
throtteling, e.g. either due to GPU load or CPU load, or information on
the GPU backlog.

Helmut

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