netdev - Re: [PATCH v1 net-next 2/2] tcp: reorganize tcp

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Message-ID: <73b28f6e-e6de-41a8-8622-3d58832e1582@kernel.org>
Date: Tue, 5 Dec 2023 09:08:05 -0700
From: David Ahern <dsahern@...nel.org>
To: Coco Li <lixiaoyan@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Eric Dumazet <edumazet@...gle.com>, Neal Cardwell <ncardwell@...gle.com>,
 Mubashir Adnan Qureshi <mubashirq@...gle.com>,
 Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>,
 Jonathan Corbet <corbet@....net>, Daniel Borkmann <daniel@...earbox.net>
Cc: netdev@...r.kernel.org, Chao Wu <wwchao@...gle.com>,
 Wei Wang <weiwan@...gle.com>, Pradeep Nemavat <pnemavat@...gle.com>
Subject: Re: [PATCH v1 net-next 2/2] tcp: reorganize tcp_sock fast path
 variables

On 12/4/23 1:12 PM, Coco Li wrote:
> The variables are organized according in the following way:
> 
> - TX read-mostly hotpath cache lines
> - TXRX read-mostly hotpath cache lines
> - RX read-mostly hotpath cache lines
> - TX read-write hotpath cache line
> - TXRX read-write hotpath cache line
> - RX read-write hotpath cache line
> 
> Fastpath cachelines end after rcvq_space.
> 
> Cache line boundaries are enforced only between read-mostly and
> read-write. That is, if read-mostly tx cachelines bleed into
> read-mostly txrx cachelines, we do not care. We care about the
> boundaries between read and write cachelines because we want
> to prevent false sharing.
> 
> Fast path variables span cache lines before change: 12
> Fast path variables span cache lines after change: 8
> 
> Suggested-by: Eric Dumazet <edumazet@...gle.com>
> Reviewed-by: Wei Wang <weiwan@...gle.com>
> Signed-off-by: Coco Li <lixiaoyan@...gle.com>
> ---
>  include/linux/tcp.h | 248 ++++++++++++++++++++++++--------------------
>  net/ipv4/tcp.c      |  93 +++++++++++++++++
>  2 files changed, 227 insertions(+), 114 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@...nel.org>