svn commit: r344368 - head/sys/netinet

[Kubilay Kocak]

On 21/02/2019 5:03 am, Michael Tuexen wrote:
> Author: tuexen
> Date: Wed Feb 20 18:03:43 2019
> New Revision: 344368
> URL: https://svnweb.freebsd.org/changeset/base/344368
> 
> Log:
>    Reduce the TCP initial retransmission timeout from 3 seconds to
>    1 second as allowed by RFC 6298.
>    
>    Reviewed by:		kbowling@, Richard Scheffenegger
>    Sponsored by:		Netflix, Inc.
>    Differential Revision:	https://reviews.freebsd.org/D18941
> 
> Modified:
>    head/sys/netinet/tcp_syncache.c
>    head/sys/netinet/tcp_timer.h
> 
> Modified: head/sys/netinet/tcp_syncache.c
> ==============================================================================
> --- head/sys/netinet/tcp_syncache.c	Wed Feb 20 17:56:38 2019	(r344367)
> +++ head/sys/netinet/tcp_syncache.c	Wed Feb 20 18:03:43 2019	(r344368)
> @@ -159,7 +159,7 @@ static int	 syncookie_cmp(struct in_conninfo *inc, str
>    *                  tcp_backoff[1] +
>    *                  tcp_backoff[2] +
>    *                  tcp_backoff[3]) + 3 * tcp_rexmit_slop,
> - * 3000 ms * (1 + 2 + 4 + 8) +  3 * 200 ms = 45600 ms,
> + * 1000 ms * (1 + 2 + 4 + 8) +  3 * 200 ms = 15600 ms,
>    * the odds are that the user has given up attempting to connect by then.
>    */
>   #define SYNCACHE_MAXREXMTS		3
> 
> Modified: head/sys/netinet/tcp_timer.h
> ==============================================================================
> --- head/sys/netinet/tcp_timer.h	Wed Feb 20 17:56:38 2019	(r344367)
> +++ head/sys/netinet/tcp_timer.h	Wed Feb 20 18:03:43 2019	(r344368)
> @@ -77,7 +77,7 @@
>   #define	TCPTV_MSL	( 30*hz)		/* max seg lifetime (hah!) */
>   #define	TCPTV_SRTTBASE	0			/* base roundtrip time;
>   						   if 0, no idea yet */
> -#define	TCPTV_RTOBASE	(  3*hz)		/* assumed RTO if no info */
> +#define	TCPTV_RTOBASE	(  1*hz)		/* assumed RTO if no info */
>   
>   #define	TCPTV_PERSMIN	(  5*hz)		/* minimum persist interval */
>   #define	TCPTV_PERSMAX	( 60*hz)		/* maximum persist interval */
> _______________________________________________

Any way this can be a run-time tunable?