netdev - Re: [PATCH net-next v2] net: ipv6: Add early demux handler for UDP unicast

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Message-Id: <20170312.225448.798984501964691999.davem@davemloft.net>
Date:   Sun, 12 Mar 2017 22:54:48 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     subashab@...eaurora.org
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net-next v2] net: ipv6: Add early demux handler for UDP
 unicast

From: Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
Date: Wed,  8 Mar 2017 16:36:49 -0700

> While running a single stream UDPv6 test, we observed that amount
> of CPU spent in NET_RX softirq was much greater than UDPv4 for an
> equivalent receive rate. The test here was run on an ARM64 based
> Android system. On further analysis with perf, we found that UDPv6
> was spending significant time in the statistics netfilter targets
> which did socket lookup per packet. These statistics rules perform
> a lookup when there is no socket associated with the skb. Since
> there are multiple instances of these rules based on UID, there
> will be equal number of lookups per skb.
> 
> By introducing early demux for UDPv6, we avoid the redundant lookups.
> This also helped to improve the performance (800Mbps -> 870Mbps) on a
> CPU limited system in a single stream UDPv6 receive test with 1450
> byte sized datagrams using iperf.
> 
> v1->v2: Use IPv6 cookie to validate dst instead of 0 as suggested
> by Eric
> 
> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>

Applied, thanks.