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Date: Wed, 17 May 2023 07:58:49 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Lorenzo Bianconi <lorenzo@kernel.org>
Cc: Maciej Fijalkowski <maciej.fijalkowski@intel.com>, Lorenzo Bianconi
 <lorenzo.bianconi@redhat.com>, Yunsheng Lin <linyunsheng@huawei.com>,
 netdev@vger.kernel.org, bpf@vger.kernel.org, davem@davemloft.net,
 edumazet@google.com, pabeni@redhat.com, ast@kernel.org,
 daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com
Subject: Re: [RFC net-next] net: veth: reduce page_pool memory footprint
 using half page per-buffer
Message-ID: <20230517075849.2af98d72@kernel.org>
In-Reply-To: <ZGQJKRfuf4+av/MD@lore-desk>
References: <d3ae6bd3537fbce379382ac6a42f67e22f27ece2.1683896626.git.lorenzo@kernel.org>
	<62654fa5-d3a2-4b81-af70-59c9e90db842@huawei.com>
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On Wed, 17 May 2023 00:52:25 +0200 Lorenzo Bianconi wrote:
> I am testing this RFC patch in the scenario reported below:
> 
> iperf tcp tx --> veth0 --> veth1 (xdp_pass) --> iperf tcp rx
> 
> - 6.4.0-rc1 net-next:
>   MTU 1500B: ~ 7.07 Gbps
>   MTU 8000B: ~ 14.7 Gbps
> 
> - 6.4.0-rc1 net-next + page_pool frag support in veth:
>   MTU 1500B: ~ 8.57 Gbps
>   MTU 8000B: ~ 14.5 Gbps
> 
> side note: it seems there is a regression between 6.2.15 and 6.4.0-rc1 net-next
> (even without latest veth page_pool patches) in the throughput I can get in the
> scenario above, but I have not looked into it yet.
> 
> - 6.2.15:
>   MTU 1500B: ~ 7.91 Gbps
>   MTU 8000B: ~ 14.1 Gbps
> 
> - 6.4.0-rc1 net-next w/o commits [0],[1],[2]
>   MTU 1500B: ~ 6.38 Gbps
>   MTU 8000B: ~ 13.2 Gbps

If the benchmark is iperf, wouldn't working towards preserving GSO
status across XDP (assuming prog is multi-buf-capable) be the most
beneficial optimization?