netdev - Re: [PATCH v2 net-next] net: use jump_label to shortcut RPS if not setup

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]

Message-ID: <1321565689.2444.5.camel@edumazet-laptop>
Date:	Thu, 17 Nov 2011 22:34:49 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>, Tom Herbert <therbert@...gle.com>
Subject: Re: [PATCH v2 net-next] net: use jump_label to shortcut RPS if not
 setup

Le jeudi 17 novembre 2011 à 14:13 +0100, Eric Dumazet a écrit :
> Most machines dont use RPS/RFS, and pay a fair amount of instructions in
> netif_receive_skb() / netif_rx() / get_rps_cpu() just to discover
> RPS/RFS is not setup.
> 
> Add a jump_label named rps_needed.
> 
> If no device rps_map or global rps_sock_flow_table is setup,
> netif_receive_skb() / netif_rx() do a single instruction instead of many
> ones, including conditional jumps.
> 
> jmp +0    (if CONFIG_JUMP_LABEL=y)
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
> CC: Tom Herbert <therbert@...gle.com>

I wonder if we could use this jump_label infrastructure to shortcut
expensive netfilter nf_hook_slow() / nf_iterate on empty
tables/chains...





--
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