[OpenJDK 2D-Dev] RFR: 8261549: Adjust memory size in MTLTexurePool.m

[Alexey Ushakov]

On Sat, 5 Jun 2021 23:46:12 GMT, Phil Race <prr at openjdk.org> wrote:

>> Used MTLDevice recommendedMaxWorkingSetSize property for optimal size of the texture pool
>
> src/java.desktop/macosx/native/libawt_lwawt/java2d/metal/MTLTexurePool.m line 328:
> 
>> 326:     if (_maxPoolMemory < MAX_POOL_MEMORY) {
>> 327:         _maxPoolMemory = MAX_POOL_MEMORY;
>> 328:     }
> 
> The Apple 5K retina is 5120‑by‑2880 pixels
> 
> So we start off with a number that is too small
> #define SCREEN_MEMORY_SIZE_4K (4096*2160*4) //~33,7 mb
> and then divide it by 2
> #define MAX_POOL_MEMORY SCREEN_MEMORY_SIZE_4K/2
> 
> and I have no idea what a typical size is for 
> self.device.recommendedMaxWorkingSetSize
> which we are also dividing by 2.
> 
> So I have no idea what the logic is behind all these numbers.

> The Apple 5K retina is 5120‑by‑2880 pixels
> 
> So we start off with a number that is too small
> #define SCREEN_MEMORY_SIZE_4K (4096_2160_4) //~33,7 mb
> and then divide it by 2
> #define MAX_POOL_MEMORY SCREEN_MEMORY_SIZE_4K/2

I didn't touch this number here, they worked well within our EA testing cycles. So, I decided to use it as a fallback. We can extend it to 5K though.

> and I have no idea what a typical size is for
> self.device.recommendedMaxWorkingSetSize
> which we are also dividing by 2.

This size typically much much bigger than  SCREEN_MEMORY_SIZE_4K 
 - 4GB on Radeon Pro 560X 4GB
 - 1.5GB Intel UHD Graphics 630 1536 MB  (MBP 2019)
 Looks like it corresponds to the amount of VRAM however the doc says that OS may set another value
 
> An approximation of how much memory, in bytes, this device can use with good performance.

I don't think that it's a good idea to take all the recommended VRAM, so decided to divide it by 2.

> 
> So I have no idea what the logic is behind all these numbers.

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PR: https://git.openjdk.java.net/jdk/pull/4279