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Message-ID: <3a5f3950-e47f-409a-b881-0c8545778b91@baylibre.com>
Date: Tue, 5 Mar 2024 11:46:00 +0100
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Subject: Re: [PATCH v2 2/2] net: ethernet: ti: am65-cpsw: Add minimal XDP
 support
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To: Andrew Lunn <andrew@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>,
 Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>,
 Paolo Abeni <pabeni@redhat.com>, Russell King <linux@armlinux.org.uk>,
 Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>,
 Jesper Dangaard Brouer <hawk@kernel.org>,
 John Fastabend <john.fastabend@gmail.com>,
 Sumit Semwal <sumit.semwal@linaro.org>,
 =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
 Simon Horman <horms@kernel.org>, netdev@vger.kernel.org,
 linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
 linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
 linaro-mm-sig@lists.linaro.org
References: <20240223-am65-cpsw-xdp-basic-v2-0-01c6caacabb6@baylibre.com>
 <20240223-am65-cpsw-xdp-basic-v2-2-01c6caacabb6@baylibre.com>
 <356f4dd4-eb0e-49fa-a9eb-4dffbe5c7e7c@lunn.ch>
From: Julien Panis <jpanis@baylibre.com>
In-Reply-To: <356f4dd4-eb0e-49fa-a9eb-4dffbe5c7e7c@lunn.ch>
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On 3/1/24 17:38, Andrew Lunn wrote:
> On Fri, Mar 01, 2024 at 04:02:53PM +0100, Julien Panis wrote:
>> This patch adds XDP (eXpress Data Path) support to TI AM65 CPSW
>> Ethernet driver. The following features are implemented:
>> - NETDEV_XDP_ACT_BASIC (XDP_PASS, XDP_TX, XDP_DROP, XDP_ABORTED)
>> - NETDEV_XDP_ACT_REDIRECT (XDP_REDIRECT)
>> - NETDEV_XDP_ACT_NDO_XMIT (ndo_xdp_xmit callback)
>>
>> The page pool memory model is used to get better performance.
> Do you have any benchmark numbers? It should help with none XDP
> traffic as well. So maybe iperf numbers before and after?
>
> 	Andrew

Argh...Houston, we have a problem. I checked my v3, which is ready for
submission, with iperf3:
1) Before = without page pool -> 500 MBits/sec
2) After = with page pool -> 442 MBits/sec
-> ~ 10% worse with page pool here.

Unless the difference is not due to page pool. Maybe there's something else
which is not good in my patch. I'm going to send the v3 which uses page pool,
hopefully someone will find out something suspicious. Meanwhile, I'll carry on
investigating: I'll check the results with my patch, by removing only the using of
page pool.

Julien