Re: [RFC] Some questions and an idea on SLUB/SLAB

[Matthew Wilcox]

On Sat, Oct 09, 2021 at 12:19:03AM +0000, Hyeonggon Yoo wrote:
>  - Is there a reason that SLUB does not implement cache coloring?
>    it will help utilizing hardware cache. Especially in block layer,
>    they are literally *squeezing* its performance now.

Have you tried turning off cache colouring in SLAB and seeing if
performance changes?  My impression is that it's useful for caches
with low associativity (direct mapped / 2-way / 4-way), but loses
its effectiveness for caches with higher associativity.  For example,
my laptop:

 L1 Data Cache: 48KB, 12-way associative, 64 byte line size
 L1 Instruction Cache: 32KB, 8-way associative, 64 byte line size
 L2 Unified Cache: 1280KB, 20-way associative, 64 byte line size
 L3 Unified Cache: 12288KB, 12-way associative, 64 byte line size

I very much doubt that cache colouring is still useful for this machine.