> The reason Andi Kleen didn't see any improvements from limiting
> 'factor' is that he is using short lived connections. If you
The netperf test is about 10s - not really short lived and should
be enough for slow start.
> have a connection up for long enough, this allows the congestion
> window to grow and then it doesn't matter.
>
> Something like the following is what I have been talking about.
> I am able to reproduce the problem here locally and the following
Cool.
> makes it go away.
>
> Andi, Anton, and niv, can you confirm it does so for you too?
Unfortunately not - with the patch applied I still get 27MB/s
Looking at the tcpdump the ack clock goes completely out of sync,
the ratio is 4 packets per ack. The sender seems to send packets
faster than the target can ack them. It eventually stops for a
short time until it gets the ack
01:16:26.034669 10.23.202.31.32777 > 10.23.202.10.34491: P
1983065:1984513(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.034713 10.23.202.10.34491 > 10.23.202.31.32777: . ack 1984513 win
63712 <nop,nop,timestamp 53583052 4294889148> (DF)
01:16:26.034902 10.23.202.31.32777 > 10.23.202.10.34491: .
1984513:1985961(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.034910 10.23.202.31.32777 > 10.23.202.10.34491: .
1985961:1987409(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.034916 10.23.202.31.32777 > 10.23.202.10.34491: .
1987409:1988857(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.034921 10.23.202.31.32777 > 10.23.202.10.34491: .
1988857:1990305(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.034926 10.23.202.31.32777 > 10.23.202.10.34491: .
1990305:1991753(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.034998 10.23.202.10.34491 > 10.23.202.31.32777: . ack 1991753 win
63712 <nop,nop,timestamp 53583052 4294889148> (DF)
01:16:26.035144 10.23.202.31.32777 > 10.23.202.10.34491: .
1991753:1993201(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.035152 10.23.202.31.32777 > 10.23.202.10.34491: .
1993201:1994649(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.035158 10.23.202.31.32777 > 10.23.202.10.34491: .
1994649:1996097(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.035163 10.23.202.31.32777 > 10.23.202.10.34491: .
1996097:1997545(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.035169 10.23.202.31.32777 > 10.23.202.10.34491: P
1997545:1998993(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.035214 10.23.202.10.34491 > 10.23.202.31.32777: . ack 1998993 win
63712 <nop,nop,timestamp 53583052 4294889148> (DF)
01:16:26.035393 10.23.202.31.32777 > 10.23.202.10.34491: .
1998993:2000441(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.035401 10.23.202.31.32777 > 10.23.202.10.34491: .
2000441:2001889(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
01:16:26.035406 10.23.202.31.32777 > 10.23.202.10.34491: .
2001889:2003337(1448) ack 1 win 1460 <nop,nop,timestamp 4294889148 53583052>
(DF)
-Andi
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