From 21d033e472735ecec677f1ae46d6740b5e47a4f3 Mon Sep 17 00:00:00 2001 From: Fernando Fernandez Mancera Date: Wed, 17 Dec 2025 15:46:41 +0100 Subject: netfilter: nf_conncount: increase the connection clean up limit to 64 After the optimization to only perform one GC per jiffy, a new problem was introduced. If more than 8 new connections are tracked per jiffy the list won't be cleaned up fast enough possibly reaching the limit wrongly. In order to prevent this issue, only skip the GC if it was already triggered during the same jiffy and the increment is lower than the clean up limit. In addition, increase the clean up limit to 64 connections to avoid triggering GC too often and do more effective GCs. This has been tested using a HTTP server and several performance tools while having nft_connlimit/xt_connlimit or OVS limit configured. Output of slowhttptest + OVS limit at 52000 connections: slow HTTP test status on 340th second: initializing: 0 pending: 432 connected: 51998 error: 0 closed: 0 service available: YES Fixes: d265929930e2 ("netfilter: nf_conncount: reduce unnecessary GC") Reported-by: Aleksandra Rukomoinikova Closes: https://lore.kernel.org/netfilter/b2064e7b-0776-4e14-adb6-c68080987471@k2.cloud/ Signed-off-by: Fernando Fernandez Mancera Signed-off-by: Florian Westphal --- include/net/netfilter/nf_conntrack_count.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/net/netfilter/nf_conntrack_count.h b/include/net/netfilter/nf_conntrack_count.h index 52a06de41aa0..cf0166520cf3 100644 --- a/include/net/netfilter/nf_conntrack_count.h +++ b/include/net/netfilter/nf_conntrack_count.h @@ -13,6 +13,7 @@ struct nf_conncount_list { u32 last_gc; /* jiffies at most recent gc */ struct list_head head; /* connections with the same filtering key */ unsigned int count; /* length of list */ + unsigned int last_gc_count; /* length of list at most recent gc */ }; struct nf_conncount_data *nf_conncount_init(struct net *net, unsigned int keylen); -- cgit v1.2.3