netdev - Re: Something hitting my total number of connections to the server

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]

Message-ID: <bf580154-aea9-4143-5d9c-df3764b5e745@gmail.com>
Date:   Tue, 22 Aug 2017 09:43:45 -0700
From:   David Ahern <dsahern@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        Akshat Kakkar <akshat.1984@...il.com>
Cc:     David Laight <David.Laight@...lab.com>,
        netdev <netdev@...r.kernel.org>
Subject: Re: Something hitting my total number of connections to the server

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."