netdev - Re: [PATCH nf-next] netfilter: flowtable: dedicated slab for flow entry

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Message-ID: <aXs14ZJGN3lDnMDc@strlen.de>
Date: Thu, 29 Jan 2026 11:26:41 +0100
From: Florian Westphal <fw@...len.de>
To: Qingfang Deng <dqfext@...il.com>
Cc: Pablo Neira Ayuso <pablo@...filter.org>, Phil Sutter <phil@....cc>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>, netfilter-devel@...r.kernel.org,
	coreteam@...filter.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Lorenzo Bianconi <lorenzo@...nel.org>
Subject: Re: [PATCH nf-next] netfilter: flowtable: dedicated slab for flow
 entry

Qingfang Deng <dqfext@...il.com> wrote:
> The size of `struct flow_offload` has grown beyond 256 bytes on 64-bit
> kernels (currently 280 bytes) because of the `flow_offload_tunnel`
> member added recently. So kmalloc() allocates from the kmalloc-512 slab,
> causing significant memory waste per entry.
> 
> Introduce a dedicated slab cache for flow entries to reduce memory
> footprint. Results in a reduction from 512 bytes to 320 bytes per entry
> on x86_64 kernels.

Ok, but please use KMEM_CACHE(), we've had a bunch of patches
that removed kmem_cache_create() in several places, I would like
to avoid a followup patch.