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From: Hyeonggon Yoo <42.hyeyoo@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Linux Memory Management List <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	 Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	 Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	 Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [RFC] Some questions and an idea on SLUB/SLAB
Date: Sat, 9 Oct 2021 11:02:09 +0900	[thread overview]
Message-ID: <CAB=+i9R207ku5eN_W6LRokpuT-0VSYo6ao--8viUuhj2uuUcbQ@mail.gmail.com> (raw)
In-Reply-To: <YWDjZ+KlkV2wKShh@casper.infradead.org>

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On Sat, Oct 9, 2021, 9:34 AM Matthew Wilcox <willy@infradead.org> wrote:

> 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.
>

And what was result on that benchmark?

How many cores on your processor?
And is it NUMA or UMA?

As I mentioned, color scheme is shared between cpus in same node.

I think we need to measure performqnce again after per-cpu coloring.

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  parent reply	other threads:[~2021-10-09  2:02 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-09  0:19 [RFC] Some questions and an idea on SLUB/SLAB Hyeonggon Yoo
2021-10-09  0:33 ` Matthew Wilcox
2021-10-09  0:40   ` Hyeonggon Yoo
2021-10-09  2:02   ` Hyeonggon Yoo [this message]
2021-10-09 11:45   ` Almost no difference Hyeonggon Yoo
2021-10-11  7:13 ` [RFC] Some questions and an idea on SLUB/SLAB Christoph Lameter
2021-10-13  3:44   ` Hyeonggon Yoo

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