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Date: Mon, 07 Jul 2008 16:00:29 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: rick.jones2@...com
Cc: aglo@...i.umich.edu, shemminger@...tta.com, netdev@...r.kernel.org,
rees@...ch.edu, bfields@...ldses.org
Subject: Re: setsockopt()
From: Rick Jones <rick.jones2@...com>
Date: Mon, 07 Jul 2008 15:50:21 -0700
> I'm still a triffle puzzled/concerned/confused by the extent to which
> autotuning will allow the receive window to grow, again based on some
> netperf experience thusfar, and patient explanations provided here and
> elsewhere, it seems as though autotuning will let things get to 2x what
> it thinks the sender's cwnd happens to be. So far under netperf testing
> that seems to be the case, and 99 times out of ten my netperf tests will
> have the window grow to the max.
We need 2x, in order to have a full window during recovery.
There was a measurement bug found a few months ago when the
google folks were probing in this area, which was fixed
by John Heffner. Most of which had to deal with TSO subtleties.
--------------------
commit 246eb2af060fc32650f07203c02bdc0456ad76c7
Author: John Heffner <johnwheffner@...il.com>
Date: Tue Apr 29 03:13:52 2008 -0700
tcp: Limit cwnd growth when deferring for GSO
This fixes inappropriately large cwnd growth on sender-limited flows
when GSO is enabled, limiting cwnd growth to 64k.
Signed-off-by: John Heffner <johnwheffner@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
commit ce447eb91409225f8a488f6b7b2a1bdf7b2d884f
Author: John Heffner <johnwheffner@...il.com>
Date: Tue Apr 29 03:13:02 2008 -0700
tcp: Allow send-limited cwnd to grow up to max_burst when gso disabled
This changes the logic in tcp_is_cwnd_limited() so that cwnd may grow
up to tcp_max_burst() even when sk_can_gso() is false, or when
sysctl_tcp_tso_win_divisor != 0.
Signed-off-by: John Heffner <johnwheffner@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
--------------------
Setting TCP socket buffer via setsockopt() is always wrong.
If there is a bug, let's fix it.
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