From b3a8a40da5751525936c88f60bbc6a007f9eee37 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Wed, 13 Sep 2006 19:51:02 -0700 Subject: [PATCH] [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: Stephen Hemminger Signed-off-by: David S. Miller --- Documentation/networking/ip-sysctl.txt | 12 +++++++++--- net/ipv4/tcp_input.c | 2 +- 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 3e0c017e787..90ed78110fd 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -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 diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 111ff39a08c..159fa3f1ba6 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -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. */ -- 2.20.1