Linux Kernel 6.13 brings an option for AMD 3D Cache Processors

[_roman_]

Note: This is not a support request topic. This is just an opinion and just for information.

This really shows how far behind we are in regards of optimisations. I see a lot of changes for the scheduler and such.



source: linux kernel / or:

Linux Kernel Driver DataBase: CONFIG_AMD_3D_VCACHE: AMD 3D V-Cache Performance Optimizer Driver

CONFIG_AMD_3D_VCACHE: AMD 3D V-Cache Performance Optimizer Driver​

General informations​

The Linux kernel configuration item CONFIG_AMD_3D_VCACHE:

• prompt: AMD 3D V-Cache Performance Optimizer Driver
• type: tristate
• depends on: CONFIG_X86_64 && CONFIG_ACPI
• defined in drivers/platform/x86/amd/Kconfig
• found in Linux kernels: 6.13
• modules built: amd_3d_vcache

Help text​

The driver provides a sysfs interface, enabling the setting of a bias that alters CPU core reordering. This bias prefers cores with higher frequencies or larger L3 caches on processors supporting AMD 3D V-Cache technology.

If you choose to compile this driver as a module the module will be called amd_3d_vcache.

Hardware​

LKDDb​

Raw data from LKDDb:

• lkddb acpi "AMDI0101" : CONFIG_AMD_3D_VCACHE CONFIG_X86 : drivers/platform/x86/amd/x3d_vcache.c # in 6.13
• lkddb module amd_3d_vcache CONFIG_AMD_3D_VCACHE : drivers/platform/x86/amd/Kconfig : "AMD 3D V-Cache Performance Optimizer Driver" # in 6.13
• lkddb platform "amd_x3d_vcache" : CONFIG_AMD_3D_VCACHE CONFIG_X86 : drivers/platform/x86/amd/x3d_vcache.c # in 6.13

Sources​

This page is automaticly generated with free (libre, open) software lkddb(see lkddb-sources).

The data is retrived from:

• Linux kernel
• Linux Kernel Driver DataBase (LKDDb)

 

[Wirko]

By "we", you mean Linux users compared to Windows users?

 

[bug]

"Far behind" means nothing in the context. It's heterogeneous computing after all. Some parameters will favor some workloads, other parameters will favor others. There will never be a day when you will wake up and say "ok, we're done, now the driver does the perfect job". There is no perfect job in this context.

 

[_roman_]

#2 We in the context of someone who has that processor, cares for optimising the operating system and uses a recent "custom" made linux kernel.

I saw a lot of optimisations in past weeks which looked like aimed for those intel P and E core processors.
There were also optimisations or changes to the scheduler a lot. In terms of security, but also a lot in terms of changed or newer kernel options.

edit: I just realised - the most affected cpus are most likely the ryzen 7950X3d or ryzen 7900X3d.
The ryzen 5800X3d, 7800X3d, 7600X3d, 5700X3d, 5600X3d should not be affected.


--

#3 there lies a lot of potential in regards of the compiler and in the form of the kernel.

e.g. less seconds to compile a code

I think it matters a lot where the code is executed on e.g. ryzen 7950X3d or ryzen 7900X3d

AMD Ryzen 9 7950X3D Review: Gamers, Don't Buy This One!

With extra L3 cache and lowered clocks for less heat, AMD is trying to make the Ryzen 9 7950X3D the best CPU for all scenarios. But how...

www.techspot.com

--

typical amd - no specs

https://www.amd.com/en/products/processors/desktops/ryzen/5000-series/amd-ryzen-7-5800x3d.html

when you look up an intel processor you see inital the launch date for any processor.

It seems the launch date was the 20th april 2022 for the ryzen 5800X3d. (~ a bit less than 3 years)

AMD Ryzen 7 5800X3D Review - The Magic of 3D V-Cache

The AMD Ryzen 7 5800X3D is the company's new flagship gaming processor. It introduces 3D V-Cache, a dedicated piece of silicon with additional L3 capacity. In our review, we're testing how much the larger cache can help intensive gaming workloads and applications and compare it to the Intel Core...

www.techpowerup.com

AMD's Ryzen 7 5800X3D Launches April 20th, Plus 6 New Low & Mid-Range Ryzen Chips

www.anandtech.com

IT looks like March 2023 was the release date for the 7950X3d cpus. (~2 years)

AMD Ryzen 9 7950X3D Review: Gamers, Don't Buy This One!

With extra L3 cache and lowered clocks for less heat, AMD is trying to make the Ryzen 9 7950X3D the best CPU for all scenarios. But how...

www.techspot.com

 

[mb194dc]

Benchmarks with this optimization v without ?

 

[igormp]

I consider the Ryzen 5800X3d one of the first processors where this kernel option should be applied to. That is very long on the market.

This would be irrelevant to the 5800x3D, since there's no bias to set given that all cores are uniform with the V-cache.
This is relevant to stuff like 7950x3D, where you have CCDs with/without the V-cache, and may want to manually set a bias in an easier manner.
FWIW, there were similar patches for stuff like P/E-cores, for both intel and AMD.

#3 there lies a lot of potential in regards of the compiler and in the form of the kernel.

e.g. less seconds to compile a code

Not really? This specific example you gave is a embarrassingly parallel workload, there's no need for a bias to certain core types when you're going to use all of those anyway.

I think it matters a lot where the code is executed on e.g. ryzen 7950X3d or ryzen 7900X3d

AMD Ryzen 9 7950X3D Review: Gamers, Don't Buy This One!

With extra L3 cache and lowered clocks for less heat, AMD is trying to make the Ryzen 9 7950X3D the best CPU for all scenarios. But how...

www.techspot.com

I don't think it's that relevant in this case, the previous scheduler iterations were already good enough when deciding where to allocate stuff. It already had "knowledge" of different frequencies and capabilities in heterogeneous CPU configs. Friendly reminder that the kernel is pretty used to dealing with multiple different clusters of CPUs in the ARM world already.