From: Neal Cardwell firstname.lastname@example.org
Date: Tue, 10 Apr 2012 13:59:20 -0400
> Fix a code path in tcp_rcv_rtt_update() that was comparing
> unscaled RTT samples.
> The intent in the code was to only use the ’m’ measurement if it was a
> new minimum. However, since ’m’ had not yet been shifted left 3 bits
> but ‘new_sample’ had, this comparison would nearly always succeed,
> leading us to erroneously set our receive-side RTT estimate to the ’m’
> sample when that sample could be nearly 8x too high to use.
> The overall effect is to often cause the receive-side RTT estimate to
> be significantly too large (up to 40% too large for brief periods in
> my tests).
> Signed-off-by: Neal Cardwell email@example.com