netdev - new sysctl tunable knob : tcp_retries2

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Date:   Mon, 31 Jul 2017 18:17:48 +0200
From:   Massimo Sala <massimo.sala.71@...il.com>
To:     netdev@...r.kernel.org
Subject: new sysctl tunable knob : tcp_retries2_time

I wish to suggest to developers to add this new knob :

tcp_retries2_time - INTEGER
	This value influences the timeout (seconds) of an alive TCP connection,
	when RTO retransmissions remain unacknowledged.
        RFC 1122 recommends at least 100 seconds for the timeout,
	which corresponds to a value of at least 8.

Rationale :
* I see a lot of misuse of tcp_retries2, because even if you check the
RTO, it will change with different connections, routing, etc... and so
tcp_retries2 timeout will change.

* An absolute value will be friendly and better ton read and document.
See other parameters with two knobs ( example : dirty_ratio,
dirty_ratio_bytes ).

Best regards, Sala