netdev - Re: [net-next PATCH 0/3] net: optimize ICMP-reply code path

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Date:   Mon, 09 Jan 2017 15:49:30 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     brouer@...hat.com
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com,
        xiyou.wangcong@...il.com
Subject: Re: [net-next PATCH 0/3] net: optimize ICMP-reply code path

From: Jesper Dangaard Brouer <brouer@...hat.com>
Date: Mon, 09 Jan 2017 16:03:59 +0100

> This patchset is optimizing the ICMP-reply code path, for ICMP packets
> that gets rate limited. A remote party can easily trigger this code
> path by sending packets to port number with no listening service.
> 
> Generally the patchset moves the sysctl_icmp_msgs_per_sec ratelimit
> checking to earlier in the code path and removes an allocation.
> 
> 
> Use-case: The specific case I experienced this being a bottleneck is,
> sending UDP packets to a port with no listener, which obviously result
> in kernel replying with ICMP Destination Unreachable (type:3), Port
> Unreachable (code:3), which cause the bottleneck.
> 
>  After Eric and Paolo optimized the UDP socket code, the kernels PPS
> processing capabilities is lower for no-listen ports, than normal UDP
> sockets.  This is bad for capacity planning when restarting a service.
> 
> UDP no-listen benchmark 8xCPUs using pktgen_sample04_many_flows.sh:
>  Baseline: 6.6 Mpps
>  Patch:   14.7 Mpps
> Driver mlx5 at 50Gbit/s.

Series applied, thanks Jesper!