netdev - TCP many-connection regression between 4.7 and 4.13 kernels.

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Message-ID: <e44000ce-1b94-f014-59c5-07305714ffcc@candelatech.com>
Date:   Mon, 22 Jan 2018 09:28:02 -0800
From:   Ben Greear <greearb@...delatech.com>
To:     netdev <netdev@...r.kernel.org>
Subject: TCP many-connection regression between 4.7 and 4.13 kernels.

My test case is to have 6 processes each create 5000 TCP IPv4 connections to each other
on a system with 16GB RAM and send slow-speed data.  This works fine on a 4.7 kernel, but
will not work at all on a 4.13.  The 4.13 first complains about running out of tcp memory,
but even after forcing those values higher, the max connections we can get is around 15k.

Both kernels have my out-of-tree patches applied, so it is possible it is my fault
at this point.

Any suggestions as to what this might be caused by, or if it is fixed in more recent kernels?

I will start bisecting in the meantime...

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com