linux-kernel - Re: [PATCH v3] net/bridge: Optimizing read-write locks in ebtables.c

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Message-ID: <20240924063258.1edfb590@fedora>
Date: Tue, 24 Sep 2024 06:32:58 -0700
From: Stephen Hemminger <stephen@...workplumber.org>
To: yushengjin <yushengjin@...ontech.com>
Cc: pablo@...filter.org, kadlec@...filter.org, roopa@...dia.com,
 razor@...ckwall.org, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com, netfilter-devel@...r.kernel.org,
 coreteam@...filter.org, bridge@...ts.linux.dev, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] net/bridge: Optimizing read-write locks in
 ebtables.c

On Tue, 24 Sep 2024 17:09:06 +0800
yushengjin <yushengjin@...ontech.com> wrote:

> When conducting WRK testing, the CPU usage rate of the testing machine was
> 100%. forwarding through a bridge, if the network load is too high, it may
> cause abnormal load on the ebt_do_table of the kernel ebtable module, leading
> to excessive soft interrupts and sometimes even directly causing CPU soft
> deadlocks.
> 
> After analysis, it was found that the code of ebtables had not been optimized
> for a long time, and the read-write locks inside still existed. However, other
> arp/ip/ip6 tables had already been optimized a lot, and performance bottlenecks
> in read-write locks had been discovered a long time ago.
> 
> Ref link: https://lore.kernel.org/lkml/20090428092411.5331c4a1@nehalam/
> 
> So I referred to arp/ip/ip6 modification methods to optimize the read-write
> lock in ebtables.c.

What about doing RCU instead, faster and safer.