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From: mengkanglai <mengkanglai2@huawei.com>
To: "David S. Miller" <davem@davemloft.net>, Eric Dumazet
	<edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, Paolo Abeni
	<pabeni@redhat.com>, Jiri Pirko <jiri@resnulli.us>, Simon Horman
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 Andrzej Siewior" <bigeasy@linutronix.de>, Lorenzo Bianconi
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CC: "Fengtao (fengtao, Euler)" <fengtao40@huawei.com>, "Yanan (Euler)"
	<yanan@huawei.com>
Subject: cpu performance drop between 4.18 and 5.10 kernel?
Thread-Topic: cpu performance drop between 4.18 and 5.10 kernel?
Thread-Index: Adqr+is3Qylu3zxvSvOZrHpOxyfQ/w==
Date: Wed, 22 May 2024 07:44:34 +0000
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Dear maintainers:
I updated my VM kernel from 4.18 to 5.10, and found that the CPU SI usage w=
as higher under the 5.10 kernel for the same udp service.
I captured the flame graph and compared the two versions of kernels.=20
Kernel 5.10 compared to 4.18 napi_complete_done function added gro_normal_l=
ist call (ommit 323ebb61e32b4 ("net: use listified RX for handling GRO_NORM=
AL
skbs") Introduced), I removed gro_normal_list from napi_complete_done in 5.=
10 kernel, CPU SI usages was same as 4.18.
I don't know much about GRO, so I'm not sure if it can be modified in this =
way, and the consequences of such a modification?