linux-kernel - Re: [PATCH V2] kmalloc_index optimization(code size & runtime stable)

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Message-ID: <20200421111849.GL5820@bombadil.infradead.org>
Date:   Tue, 21 Apr 2020 04:18:49 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     1587089010-110083-1-git-send-email-bernard@...o.com
Cc:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, opensource.kernel@...o.com,
        Bernard Zhao <bernard@...o.com>
Subject: Re: [PATCH V2] kmalloc_index optimization(code size & runtime stable)

On Mon, Apr 20, 2020 at 08:25:01PM -0700, Bernard Zhao wrote:
> kmalloc_index inline function code size optimization and runtime
> performance stability optimization. After optimization, the function
> kmalloc_index is more stable, the size will never affecte the function`s
> execution efficiency.

Please stop posting this patch until it's faster *for small sizes*.
As I explained last time you posted it, it's not an optimisation.

>             size        time/Per 100 million times
>                         old fun		new fun with optimise
> 		8	203777		241934
> 		16	245611		409278
> 		32	236384		408419
> 		64	275499		447732
> 		128	354909		416439

^^^^ these are the important cases that need to be fast.