linux-kernel - Re: [PATCH v3 09/14] x86: Minimal SLAB alignment

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Message-ID: <0770a3d4-c8ff-4172-9eda-c9debfee6d03@intel.com>
Date: Wed, 9 Apr 2025 08:24:11 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
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Subject: Re: [PATCH v3 09/14] x86: Minimal SLAB alignment

On 4/9/25 05:49, Maciej Wieczor-Retman wrote:
> The differences looked mostly like noise, sometimes the higher alignment would
> use up a little bit less memory, sometimes a little bit more. I looked at all
> values in "cat /proc/meminfo".
> 
> Is there some slab/slub benchmark for the kernel that would make sense to
> checkout here?

You don't need to benchmark anything. Just mention that it will waste
memory and also give *some* ballpark estimate on how much. Just looking
at your laptop's /proc/slabinfo would be a good start.

Oh, and it wouldn't hurt to find out when and why the minimal slab
alignment got dropped down to 8 bytes. I _thought_ it was higher at some
point. Presumably there was a good reason for it and you're now undoing
part of it.