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

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Message-ID: <CAA5aLPgA+YzavA8tw6uqfR8d6r058OymJOE+jevVmDA2Ar21rg@mail.gmail.com>
Date:   Wed, 23 Aug 2017 10:38:50 +0530
From:   Akshat Kakkar <akshat.1984@...il.com>
To:     Neal Cardwell <ncardwell@...gle.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        David Laight <David.Laight@...lab.com>,
        netdev <netdev@...r.kernel.org>
Subject: Re: Something hitting my total number of connections to the server

On Tue, Aug 22, 2017 at 5:58 PM, Neal Cardwell <ncardwell@...gle.com> wrote:
> On Tue, Aug 22, 2017 at 1:42 AM, Akshat Kakkar <akshat.1984@...il.com> wrote:
>> There are multiple hosts/clients. All are mainly windows based.
>>
>> Timestamp is not used as my clients mainly are windows based and in
>> that it tcp timestamp is by defauly disabled.
> ...
>> net.ipv4.tcp_tw_reuse=1
>> net.ipv4.tcp_tw_recycle=1
>
> I suspect the problem is there. The net.ipv4.tcp_tw_recycle setting
> should be 0. Running with the value 1 is known to cause buggy behavior
> related to TCP timestamps, and that feature has been removed in kernel
> v4.12.
>
> Can you please re-run your tests with net.ipv4.tcp_tw_recycle=0 or a
> newer kernel?
>
> neal

Thanks for your reply.

I understand that.

But my point is, though tcp timestamp is enabled on the server, but as
client is not using it ... so how come this _bug_ (if any) is
triggered in first place.