netdev - Re: [PATCH] ipv6: Enable RFS sk_rxhash tracking for ipv6 sockets

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 06 Apr 2011 20:07:33 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Neil Horman <nhorman@...driver.com>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	"Pekka Savola (ipv6)" <pekkas@...core.fi>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>,
	Tom Herbert <therbert@...gle.com>
Subject: Re: [PATCH] ipv6: Enable RFS sk_rxhash tracking for ipv6 sockets

Le mercredi 06 avril 2011 à 13:54 -0400, Neil Horman a écrit :

> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index d7037c0..aa3e327 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -505,6 +505,8 @@ int udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
>  	int rc;
>  	int is_udplite = IS_UDPLITE(sk);
>  
> +	sock_rps_save_rxhash(sk, skb->rxhash);
> +
>  	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
>  		goto drop;
>  

Problem is every packet received might have a different rxhash if
multiple senders are active. 

This can hurt performance (cache misses on RFS table) on a DNS server
workload for example.

This is why we used on ipv4 :

if (inet_sk(sk)->inet_daddr)
	sock_rps_save_rxhash(sk, skb->rxhash);


Only arm RFS on UDP if socket is bound to a given remote peer.

BTW you forgot Tom Herbert. (I added him in CC)



--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html