linux-kernel - Re: Performance regression in ip_set

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Message-ID: <a4dfc3d9-f028-7ab4-c3a7-11dcbb12e377@netfilter.org>
Date: Wed, 10 Jan 2024 11:35:02 +0100 (CET)
From: Jozsef Kadlecsik <kadlec@...filter.org>
To: David Wang <00107082@....com>
cc: ale.crismani@...omattic.com, xiaolinkui@...inos.cn, pablo@...filter.org, 
    linux-kernel@...r.kernel.org, netfilter-devel@...r.kernel.org
Subject: Re: Performance regression in ip_set_swap on 6.1.69

On Wed, 10 Jan 2024, David Wang wrote:

> I confirmed this on 6.7 that this was introduced by commit 
> 28628fa952fefc7f2072ce6e8016968cc452b1ba with following changes:
> 
> 	 static inline void
> 	@@ -1397,6 +1394,9 @@ static int ip_set_swap(struct sk_buff *skb, const struct nfnl_info *info,
> 		ip_set(inst, to_id) = from;
> 		write_unlock_bh(&ip_set_ref_lock);
> 	 
> 	+       /* Make sure all readers of the old set pointers are completed. */
> 	+       synchronize_rcu();
> 	+
> 		return 0;
> 	 }
> 
> synchronize_rcu causes the delay, and its usage here is very confusing, 
> there is no reclaimer code after it.

As I'm seeing just the end of the discussion, please send a full report of 
the problem and how to reproduce it.

Best regards,
Jozsef
-- 
E-mail  : kadlec@...ckhole.kfki.hu, kadlecsik.jozsef@...ner.hu
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Address : Wigner Research Centre for Physics
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