netdev - Re: [PATCH net-next v5] net: Add sysctl to toggle early demux for tcp and udp

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Message-Id: <20170324.132106.869851609280213495.davem@davemloft.net>
Date:   Fri, 24 Mar 2017 13:21:06 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     subashab@...eaurora.org
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com,
        stephen@...workplumber.org, tom@...bertland.com
Subject: Re: [PATCH net-next v5] net: Add sysctl to toggle early demux for
 tcp and udp

From: Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
Date: Thu, 23 Mar 2017 13:34:16 -0600

> Certain system process significant unconnected UDP workload.
> It would be preferrable to disable UDP early demux for those systems
> and enable it for TCP only.
> 
> By disabling UDP demux, we see these slight gains on an ARM64 system-
> 782 -> 788Mbps unconnected single stream UDPv4
> 633 -> 654Mbps unconnected UDPv4 different sources
> 
> The performance impact can change based on CPU architecure and cache
> sizes. There will not much difference seen if entire UDP hash table
> is in cache.
> 
> Both sysctls are enabled by default to preserve existing behavior.
> 
> v1->v2: Change function pointer instead of adding conditional as
> suggested by Stephen.
> 
> v2->v3: Read once in callers to avoid issues due to compiler
> optimizations. Also update commit message with the tests.
> 
> v3->v4: Store and use read once result instead of querying pointer
> again incorrectly.
> 
> v4->v5: Refactor to avoid errors due to compilation with IPV6={m,n}
> 
> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
> Suggested-by: Eric Dumazet <edumazet@...gle.com>

Applied.