From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Ahern <dsahern@gmail.com>
Subject: Re: Something hitting my total number of connections to the server
Date: Tue, 22 Aug 2017 09:43:45 -0700
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Cc: David Laight <David.Laight@aculab.com>,
        netdev <netdev@vger.kernel.org>
To: Eric Dumazet <eric.dumazet@gmail.com>,
        Akshat Kakkar <akshat.1984@gmail.com>
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On 8/22/17 6:02 AM, Eric Dumazet wrote:
>>
>> net.core.netdev_max_backlog=10000
> This is an insane backlog.
> 

https://www.kernel.org/doc/Documentation/networking/scaling.txt

"== Suggested Configuration

Flow limit is useful on systems with many concurrent connections,
where a single connection taking up 50% of a CPU indicates a problem.
In such environments, enable the feature on all CPUs that handle
network rx interrupts (as set in /proc/irq/N/smp_affinity).

The feature depends on the input packet queue length to exceed
the flow limit threshold (50%) + the flow history length (256).
Setting net.core.netdev_max_backlog to either 1000 or 10000
performed well in experiments."