linux-kernel - Re: [PATCH v2 2/2] selftests: net: Add FIN_ACK processing order related latency spike test

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Date:   Sat, 1 Feb 2020 10:20:08 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     sj38.park@...il.com, edumazet@...gle.com
Cc:     davem@...emloft.net, aams@...zon.com, ncardwell@...gle.com,
        netdev@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org, shuah@...nel.org, ycheng@...gle.com,
        David.Laight@...LAB.COM, SeongJae Park <sjpark@...zon.de>
Subject: Re: [PATCH v2 2/2] selftests: net: Add FIN_ACK processing order
 related latency spike test



On 1/31/20 11:18 PM, sj38.park@...il.com wrote:
> From: SeongJae Park <sjpark@...zon.de>
> 
> This commit adds a test for FIN_ACK process races related reconnection
> latency spike issues.  The issue has described and solved by the
> previous commit ("tcp: Reduce SYN resend delay if a suspicous ACK is
> received").
> 
> The test program is configured with a server and a client process.  The
> server creates and binds a socket to a port that dynamically allocated,
> listen on it, and start a infinite loop.  Inside the loop, it accepts
> connection, reads 4 bytes from the socket, and closes the connection.
> The client is constructed as an infinite loop.  Inside the loop, it
> creates a socket with LINGER and NODELAY option, connect to the server,
> send 4 bytes data, try read some data from server.  After the read()
> returns, it measure the latency from the beginning of this loop to this
> point and if the latency is larger than 1 second (spike), print a
> message.
> 
> Signed-off-by: SeongJae Park <sjpark@...zon.de>

Reviewed-by: Eric Dumazet <edumazet@...gle.com>