serious networking (em) performance (ggate and NFS) problem
Shunsuke SHINOMIYA
shino at fornext.org
Sun Nov 21 19:55:27 PST 2004
Thank you, Matt.
>
> Very interesting, but the only reason you get lower results is simply
> because the TCP window is not big enough. That's it.
>
Yes, I knew that adjusting TCP window size is important to use up a link.
However I wanted to show adjusting the parameters of Interrupt
Moderation affects network performance.
And I think a packet loss was occured by enabled Interrupt Moderation.
The mechanism of a packet loss in this case is not cleared, but I think
inappropriate TCP window size is not the only reason.
I found TCP throuput improvement at disabled Interrupt Moderation is related
to congestion avoidance phase of TCP. Because these standard deviations are
decreased when Interrupt Moderation is disabled.
The following two results are outputs of `iperf -P 10'. without TCP
window size adjustment too. I think, the difference of each throughput
at same measurement shows congestion avoidance worked.
o with default setting of Interrupt Moderation.
> [ ID] Interval Transfer Bandwidth
> [ 13] 0.0-10.0 sec 80.1 MBytes 67.2 Mbits/sec
> [ 11] 0.0-10.0 sec 121 MBytes 102 Mbits/sec
> [ 12] 0.0-10.0 sec 98.9 MBytes 83.0 Mbits/sec
> [ 4] 0.0-10.0 sec 91.8 MBytes 76.9 Mbits/sec
> [ 7] 0.0-10.0 sec 127 MBytes 106 Mbits/sec
> [ 5] 0.0-10.0 sec 106 MBytes 88.8 Mbits/sec
> [ 6] 0.0-10.0 sec 113 MBytes 94.4 Mbits/sec
> [ 10] 0.0-10.0 sec 117 MBytes 98.2 Mbits/sec
> [ 9] 0.0-10.0 sec 113 MBytes 95.0 Mbits/sec
> [ 8] 0.0-10.0 sec 93.0 MBytes 78.0 Mbits/sec
> [SUM] 0.0-10.0 sec 1.04 GBytes 889 Mbits/sec
o with disabled Interrupt Moderation.
> [ ID] Interval Transfer Bandwidth
> [ 7] 0.0-10.0 sec 106 MBytes 88.9 Mbits/sec
> [ 10] 0.0-10.0 sec 107 MBytes 89.7 Mbits/sec
> [ 8] 0.0-10.0 sec 107 MBytes 89.4 Mbits/sec
> [ 9] 0.0-10.0 sec 107 MBytes 90.0 Mbits/sec
> [ 11] 0.0-10.0 sec 106 MBytes 89.2 Mbits/sec
> [ 12] 0.0-10.0 sec 104 MBytes 87.6 Mbits/sec
> [ 4] 0.0-10.0 sec 106 MBytes 88.7 Mbits/sec
> [ 13] 0.0-10.0 sec 106 MBytes 88.9 Mbits/sec
> [ 5] 0.0-10.0 sec 106 MBytes 88.9 Mbits/sec
> [ 6] 0.0-10.0 sec 107 MBytes 89.9 Mbits/sec
> [SUM] 0.0-10.0 sec 1.04 GBytes 891 Mbits/sec
But, By decreasing TCP windows size, it could avoid.
o with default setting of Interrupt Moderation and iperf -P 10 -w 28.3k
> [ ID] Interval Transfer Bandwidth
> [ 12] 0.0-10.0 sec 111 MBytes 93.0 Mbits/sec
> [ 4] 0.0-10.0 sec 106 MBytes 88.8 Mbits/sec
> [ 11] 0.0-10.0 sec 107 MBytes 89.9 Mbits/sec
> [ 9] 0.0-10.0 sec 109 MBytes 91.6 Mbits/sec
> [ 5] 0.0-10.0 sec 109 MBytes 91.5 Mbits/sec
> [ 13] 0.0-10.0 sec 108 MBytes 90.8 Mbits/sec
> [ 10] 0.0-10.0 sec 107 MBytes 89.7 Mbits/sec
> [ 8] 0.0-10.0 sec 110 MBytes 92.3 Mbits/sec
> [ 6] 0.0-10.0 sec 111 MBytes 93.2 Mbits/sec
> [ 7] 0.0-10.0 sec 108 MBytes 90.6 Mbits/sec
> [SUM] 0.0-10.0 sec 1.06 GBytes 911 Mbits/sec
Measureing TCP throughput was not appropriate way to indicate an effect
of Interrupt Moderation clearly. It's my mistake. TCP is too
complicated. :)
--
Shunsuke SHINOMIYA <shino at fornext.org>
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