x265 HEVC Encoder

[tormento]

Originally Posted by excellentswordfight

But AFAIK the downclocking of AVX512 load have been improved since its introduction, and was less of an issue on consumer desktop models were frequency control is possible. But given what i've seen, i'm pretty sure that running it with AVX512 produces worse performance/watt.

It’s proven that AVX512 has more performance per watt. About downclocking: if you have a powerful heatsink AFAIK you can disable downclocking in bios.

[excellentswordfight]

Originally Posted by tormento

It’s proven that AVX512 has more performance per watt

Proven? For all systems with all software? Its pretty much a fact that has been worse for my cases; were enterprise-server hardware has been used. These systems are pretty strict in staying within it's power-specification, so when I get worse performance with AVX512 enabled, but it consumes the same amount of power (I have not messured the powerdraw this mind you, but im pretty sure thats the case given tempeture and freqency readings), then it means that it has a negative impact on performance/w. There are software were AVX512 instructions can do wonders, were it boosts performance by a great ammount, and there im sure that it has performance per watts benefits. But for x265, the performance gains of AVX512 are not that big, and at least with older generation hardware performance per watt has been lower, so unless you also increase power it have given me no gains.

About downclocking: if you have a powerful heatsink AFAIK you can disable downclocking in bios.

Yes, and thats also why i wrote:

"...less of an issue on consumer desktop models were frequency control is possible"

I have only tested AVX512 on Xeon/server hardware, and my old ice lake laptop. But as I said, I will try it on Sapphire Rapids, it will be interesting to see how it has been improved, cause first gen, both xeon and consumer (ice-lake) the downclocking rather big.

[nevcairiel]

AVX512 benefits start if you use it well and thoroughly, using it sparsely or inefficiently can cause more overhead then gain.
Blanket statements never make sense with complex optimizations and complex software. Test your own use-case on your own hardware.

[Atak_Snajpera]

Avx512 will be soon abandoned by Intel. AVX10 is a new toy.

[MeteorRain]

Originally Posted by DMD

I apologize but maybe that is why in the latest release of Patman86 the avx512 version does not appear?
https://github.com/Patman86/x265-Mod-by-Patman/releases

Thank you

That's just a targeted build, which affects everything other than the core part. The core will still run at different instruction set (meaning you should be able to use AVX512 on a sandy bridge build if you wish). Only the C++ code (which is not part of the core parts) will target at a different instruction set.

Originally Posted by tormento

I'd be curious to see AVX2 vs AVX512 performances of a very noisy source in very slow/placebo preset on modern CPUs.
Unfortunately the choice for Intel is now limited to 11 series and Xeons.
I need to decide if to go with Arrow Lake or Zen 5.
Not having AVX512 could be a big no no, as a lot of plugins and software that I use support that instruction set.
AVX10 for Arrow Lake is a big enigma, as it's not completely confirmed if it will be 10.1 (no AVX512) or 10.2.

AVX512 on different CPUs with different implementations will behave differently. On Zen4 you should generally see slight improvement with AVX512, while on an Intel CPU you'll see some throttling and slow down if you mix AVX512 workload with AVX2 ones.

Zen4 basically runs AVX512 on AVX2 platform, but since some AVX512 instructions are more efficient than their plain AVX2 equivalent, speed sees some improvement.
Intel CPUs runs AVX512 natively, so they do get great improvement. However Intel CPU has that infamous clock throttling so it clocks lower, impacting normal workloads.

It'll end up being a personal preference. AVX10 is a new thing and will take time to adopt. And AVX10 is, well, to just put "AVX512" back to existing product line.

Just my 2 cents.

[tormento]

Originally Posted by MeteorRain

It'll end up being a personal preference. AVX10 is a new thing and will take time to adopt. And AVX10 is, well, to just put "AVX512" back to existing product line.

AVX 10.1 will be a subset of AVX512. With 10.2 they will embrace and improve AVX512.

[Boulder]

I really wouldn't hold my breath waiting for x265 to get big optimizations regarding any new instruction sets.