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Date:   Sat, 9 Oct 2021 01:33:43 +0100
From:   Matthew Wilcox <>
To:     Hyeonggon Yoo <>
        Christoph Lameter <>,
        Pekka Enberg <>,
        David Rientjes <>,
        Joonsoo Kim <>,
        Andrew Morton <>,
        Vlastimil Babka <>
Subject: Re: [RFC] Some questions and an idea on SLUB/SLAB

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.

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