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Re: [Public WebGL] WebGL API for available memory?



Providing the currently available video memory is not possible in the
general case. For example, GL_ATI_meminfo has three different classes
of memory, and within each class, both a main pool and something
called "auxiliary memory" which is not precisely defined. On Mac OS,
the AMD OpenGL driver doesn't currently provide the "Current Free
Video Memory" variable as the Intel and NVIDIA drivers do -- though
this is just a bug which is going to be fixed. In addition, unified
memory architectures obsolete the notion of dedicated video memory.

The last time this topic was raised within various working groups in
the Khronos organization, there was strong opposition to exposing this
information.

This having been said, I would like to at least provide via a WebGL
extension the amount of dedicated video memory on the system, if using
a dedicated GPU, or, if using a unified memory architecture, the
amount of physical memory on the system. This could at least provide a
vague idea to applications how much video memory they can reasonably
allocate, even if it doesn't take into account other running
applications on the system. Before making any such extension final, it
would be necessary to test it with real-world applications. Evan,
would you be willing to help test such an extension and see how well
it works for your use case?

-Ken


On Wed, Mar 6, 2013 at 2:39 PM, Florian Bösch <pyalot@gmail.com> wrote:
> The two extension by nvidia/ati seem to cover some common functionality,
> there are also a number of ways to query values like that trough DirectX.
> These cover the rather tricky topic of telling how much is free (not just
> how much is available). We would be in principle free to define a
> WEBGL_meminfo extension, that collates this information behind a common
> interface. It is not possible on mobile devices (and not very useful on
> devices with shared memory). But it's biggest use would not be on mobile
> devices anyway.
>
>
> On Wed, Mar 6, 2013 at 11:22 PM, Ben Vanik <benvanik@google.com> wrote:
>>
>> This is probably the most asked for feature I've seen with WebGL. I still
>> really wish it would be 'solved' - even if it's not perfect, *any*
>> information (you have <512mb or >512mb of vram) would be immediately helpful
>> to developers *and* users (who are getting crashed tabs, sluggish machines,
>> or worse).
>>
>>
>> On Wed, Mar 6, 2013 at 2:08 PM, Evan Wallace <evan.exe@gmail.com> wrote:
>>>
>>> You are correct that it's not part of the OpenGL spec, however there are
>>> often ways to query this information. Look at these extensions, for example:
>>>
>>>
>>> http://developer.download.nvidia.com/opengl/specs/GL_NVX_gpu_memory_info.txt
>>> http://www.opengl.org/registry/specs/ATI/meminfo.txt
>>>
>>> The number reported also doesn't need to be exact since it's only a hint.
>>>
>>>
>>> On Wed, Mar 6, 2013 at 1:52 PM, Patrick Baggett
>>> <baggett.patrick@gmail.com> wrote:
>>>>
>>>> There is no such API to do this from OpenGL / OpenGL ES itself, so it is
>>>> not possible.
>>>>
>>>> Patrick
>>>>
>>>>
>>>> On Wed, Mar 6, 2013 at 3:33 PM, Evan Wallace <evan.exe@gmail.com> wrote:
>>>>>
>>>>> I am interested in building complex WebGL applications that operate on
>>>>> large datasets. One of the main barriers for me is that there is no way to
>>>>> tell how much memory is available on the user's machine. If a WebGL app uses
>>>>> too much memory then it starts thrashing the GPU, which causes lots of lag
>>>>> for the entire OS and is a very bad user experience. I've currently been
>>>>> dealing with it by trying to use as little memory as possible and swapping
>>>>> out memory with the CPU as the computation progresses but it's a shame not
>>>>> to run faster on hardware with more memory.
>>>>>
>>>>> My first attempt to get this information was to look at the RENDERER
>>>>> string and then compile a map of graphics cards to memory sizes, but from
>>>>> what I understand this information has been removed to prevent system
>>>>> fingerprinting and fragile string-based version sniffing (see
>>>>> https://www.khronos.org/webgl/public-mailing-list/archives/1011/threads.html#00205).
>>>>>
>>>>> My second attempt was to slowly allocate more and more memory until a
>>>>> slowdown is detected, but this is undesirable for several reasons. It takes
>>>>> a lot of time to perform which hurts startup time, it's a fragile
>>>>> measurement since lots of other things can also cause similar slowdowns
>>>>> (another app opening, for example), and once the GPU memory limit has been
>>>>> exceeded the lag due to thrashing can be pretty bad (I've observed
>>>>> system-wide graphical pauses lasting around a second) and/or cause other
>>>>> stability problems.
>>>>>
>>>>> I'm wondering if it would be possible to develop an API to determine
>>>>> the amount of available memory on the GPU, probably as a WebGL extension.
>>>>> Since it provides the relative amount currently left instead of the absolute
>>>>> total amount, it would be both much more useful to WebGL apps and far less
>>>>> useful for fingerprinting. Thoughts?
>>>>>
>>>>> Evan Wallace
>>>>>
>>>>
>>>
>>
>

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