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Commit b3a8a40d authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
Browse files

[TCP]: Turn ABC off. 



Turn Appropriate Byte Count off by default because it unfairly
penalizes applications that do small writes.  Add better documentation
to describe what it is so users will understand why they might want to
turn it on.

Signed-off-by: default avatarStephen Hemminger <shemminger@osdl.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3fcde74b

Documentation/networking/ip-sysctl.txt

+9 −3
Original line number Diff line number Diff line
@@ -102,9 +102,15 @@ inet_peer_gc_maxtime - INTEGER 
TCP variables: 



tcp_abc - INTEGER

	Controls Appropriate Byte Count defined in RFC3465. If set to

	0 then does congestion avoid once per ack. 1 is conservative

	value, and 2 is more agressive.

	Controls Appropriate Byte Count (ABC) defined in RFC3465.

	ABC is a way of increasing congestion window (cwnd) more slowly

	in response to partial acknowledgments.

	Possible values are:

		0 increase cwnd once per acknowledgment (no ABC)

		1 increase cwnd once per acknowledgment of full sized segment

		2 allow increase cwnd by two if acknowledgment is

		  of two segments to compensate for delayed acknowledgments.

	Default: 0 (off)



tcp_syn_retries - INTEGER

	Number of times initial SYNs for an active TCP connection attempt

net/ipv4/tcp_input.c

+1 −1
Original line number Diff line number Diff line
@@ -89,7 +89,7 @@ int sysctl_tcp_frto; 
int sysctl_tcp_nometrics_save;



int sysctl_tcp_moderate_rcvbuf = 1;

int sysctl_tcp_abc = 1;

int sysctl_tcp_abc;



#define FLAG_DATA		0x01 /* Incoming frame contained data.		*/

#define FLAG_WIN_UPDATE		0x02 /* Incoming ACK was a window update.	*/