tcp: allow to turn tcp timestamp randomization off
Eric says: "By looking at tcpdump, and TS val of xmit packets of multiple
flows, we can deduct the relative qdisc delays (think of fq pacing).
This should work even if we have one flow per remote peer."
Having random per flow (or host) offsets doesn't allow that anymore so add
a way to turn this off.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 5af48dd..5ca567f 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -610,8 +610,13 @@
with the current initial RTO of 1second. With this the final timeout
for an active TCP connection attempt will happen after 127seconds.
-tcp_timestamps - BOOLEAN
- Enable timestamps as defined in RFC1323.
+tcp_timestamps - INTEGER
+Enable timestamps as defined in RFC1323.
+ 0: Disabled.
+ 1: Enable timestamps as defined in RFC1323 and use random offset for
+ each connection rather than only using the current time.
+ 2: Like 1, but without random offsets.
+ Default: 1
tcp_min_tso_segs - INTEGER
Minimal number of segments per TSO frame.