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Date: Mon, 8 May 2023 19:05:15 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Cathy Zhang <cathy.zhang@intel.com>
Cc: edumazet@google.com, davem@davemloft.net, pabeni@redhat.com,
 jesse.brandeburg@intel.com, suresh.srinivas@intel.com,
 tim.c.chen@intel.com, lizhen.you@intel.com, eric.dumazet@gmail.com,
 netdev@vger.kernel.org
Subject: Re: [PATCH net-next 2/2] net: Add sysctl_reclaim_threshold
Message-ID: <20230508190515.60f090c7@kernel.org>
In-Reply-To: <20230508020801.10702-3-cathy.zhang@intel.com>
References: <20230508020801.10702-1-cathy.zhang@intel.com>
	<20230508020801.10702-3-cathy.zhang@intel.com>
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On Sun,  7 May 2023 19:08:01 -0700 Cathy Zhang wrote:
> Add a new ABI /proc/sys/net/core/reclaim_threshold which allows to
> change the size of reserved memory from reclaiming in sk_mem_uncharge.
> It allows to keep sk->sk_forward_alloc as small as possible when
> system is under memory pressure, it also allows to change it larger to
> avoid memcg charge overhead and improve performance when system is not
> under memory pressure. The original reclaim threshold for reserved
> memory per-socket is 2MB, it's selected as the max value, while the
> default value is 64KB which is closer to the maximum size of sk_buff.
> 
> Issue the following command as root to change the default value:
> 
> 	echo 16384 > /proc/sys/net/core/reclaim_threshold

While we wait for Eric to pass judgment - FWIW to me it seems a bit
overzealous to let users tune this. Does cgroup memory accounting
or any other socket memory accounting let users control the batching
parameters?