netdev - Re: [PATCH net-next] ipv4: PKTINFO doesnt need dst reference

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, 09 Nov 2011 16:37:08 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	bhutchings@...arflare.com, pstaszewski@...are.pl,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] ipv4: PKTINFO doesnt need dst reference

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Wed, 09 Nov 2011 18:24:35 +0100

> [PATCH net-next] ipv4: IP_PKTINFO doesnt need dst reference
> 
> When a socket uses IP_PKTINFO notifications, we currently force a dst
> reference for each received skb. Reader has to access dst to get needed
> information (rt_iif & rt_spec_dst) and must release dst reference.
> 
> We also forced a dst reference if skb was put in socket backlog, even
> without IP_PKTINFO handling. This happens under stress/load.
> 
> We can instead store the needed information in skb->cb[], so that only
> softirq handler really access dst, improving cache hit ratios.
> 
> This removes two atomic operations per packet, and false sharing as
> well.
> 
> On a benchmark using a mono threaded receiver (doing only recvmsg()
> calls), I can reach 720.000 pps instead of 570.000 pps.
> 
> IP_PKTINFO is typically used by DNS servers, and any multihomed aware
> UDP application.
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>

Looks good, if it compiles I'll push it out to net-next :-)
--
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