Re: Problematic throughput numbers

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Sep 25, 2024 at 12:36:43PM -0400, Jon Maloy wrote:
> I made many runs with iperf3 ns->host, and the results are puzzling me.
> Over and over again, I see throughput practically collapse, with a two
> orders of magnitude decrease.
> Just to make sure this wasn't something introduced by me, I went back to the
> master branch and disabled the SO_PEEK_OFF feature.
> The result was the same.
> The below log shows typical run, but it is highly variable.
> Sometimes almost the whole series is in the 50-70 Gb/s range, and sometimes
> almost all in the 100-300 Mb/s range.
> When I added the kernel fix it didn't seem to make any difference.
> 
> To me this is really worrying, and should be investigated.

Those numbers are certainly worrying.  Like Stefano, though, I have
encountered this myself.

> 
> ///jon
> 
> 
> 
> 
> pasta NS->host (master branch, SO_PEEK_OFF disabled
> 
> -----------------------------------------------------------
> Server listening on 5201 (test #2)
> -----------------------------------------------------------
> Accepted connection from 127.0.0.1, port 48354
> [  5] local 127.0.0.1 port 5201 connected to 127.0.0.1 port 48360
> [ ID] Interval           Transfer     Bitrate
> [  5]   0.00-1.00   sec  7.61 GBytes  65.3 Gbits/sec
> [  5]   1.00-2.00   sec  7.59 GBytes  65.2 Gbits/sec
> [  5]   2.00-3.00   sec  7.55 GBytes  64.8 Gbits/sec
> [  5]   3.00-4.00   sec  7.69 GBytes  66.1 Gbits/sec
> [  5]   4.00-5.00   sec  7.55 GBytes  64.8 Gbits/sec
> [  5]   5.00-6.00   sec  7.60 GBytes  65.3 Gbits/sec
> [  5]   6.00-7.00   sec  7.52 GBytes  64.6 Gbits/sec
> [  5]   7.00-8.00   sec  1.02 GBytes  8.73 Gbits/sec
> [  5]   8.00-9.00   sec  3.50 MBytes  29.4 Mbits/sec
> [  5]   9.00-10.00  sec  17.2 MBytes   145 Mbits/sec
> [  5]  10.00-11.00  sec  64.0 MBytes   537 Mbits/sec
> [  5]  11.00-12.00  sec  24.1 MBytes   202 Mbits/sec
> [  5]  12.00-13.00  sec  25.4 MBytes   213 Mbits/sec
> [  5]  13.00-14.00  sec  24.9 MBytes   209 Mbits/sec
> [  5]  14.00-15.00  sec  21.4 MBytes   179 Mbits/sec
> [  5]  15.00-16.00  sec  32.0 MBytes   268 Mbits/sec
> [  5]  16.00-17.00  sec  10.9 MBytes  91.2 Mbits/sec
> [  5]  17.00-18.00  sec  27.6 MBytes   232 Mbits/sec
> [  5]  18.00-19.00  sec  75.6 MBytes   634 Mbits/sec
> [  5]  19.00-20.00  sec  21.1 MBytes   177 Mbits/sec
> [  5]  20.00-21.00  sec   109 MBytes   912 Mbits/sec
> [  5]  21.00-22.00  sec  23.9 MBytes   200 Mbits/sec
> [  5]  22.00-23.00  sec  62.6 MBytes   525 Mbits/sec
> [  5]  23.00-24.00  sec  34.5 MBytes   289 Mbits/sec
> [  5]  24.00-25.00  sec  54.4 MBytes   456 Mbits/sec
> [  5]  25.00-26.00  sec  14.1 MBytes   118 Mbits/sec
> [  5]  26.00-27.00  sec  38.8 MBytes   325 Mbits/sec
> [  5]  27.00-28.00  sec  95.0 MBytes   797 Mbits/sec
> [  5]  28.00-29.00  sec  23.2 MBytes   195 Mbits/sec
> [  5]  29.00-30.00  sec  71.9 MBytes   603 Mbits/sec
> [  5]  30.00-31.00  sec  28.8 MBytes   241 Mbits/sec
> [  5]  31.00-32.00  sec  34.8 MBytes   292 Mbits/sec
> [  5]  32.00-33.00  sec  19.4 MBytes   163 Mbits/sec
> [  5]  33.00-34.00  sec  39.1 MBytes   328 Mbits/sec
> [  5]  34.00-35.00  sec  31.4 MBytes   263 Mbits/sec
> [  5]  35.00-36.00  sec  28.2 MBytes   237 Mbits/sec
> [  5]  36.00-37.00  sec  48.5 MBytes   407 Mbits/sec
> [  5]  37.00-38.00  sec  23.4 MBytes   196 Mbits/sec
> [  5]  38.00-39.00  sec  71.4 MBytes   599 Mbits/sec
> [  5]  39.00-40.00  sec  41.4 MBytes   347 Mbits/sec
> [  5]  40.00-41.00  sec  15.2 MBytes   128 Mbits/sec
> [  5]  41.00-42.00  sec  34.1 MBytes   286 Mbits/sec
> [  5]  42.00-43.00  sec  31.1 MBytes   261 Mbits/sec
> [  5]  43.00-44.00  sec  61.5 MBytes   516 Mbits/sec
> [  5]  44.00-45.00  sec  38.2 MBytes   321 Mbits/sec
> [  5]  45.00-46.00  sec  34.2 MBytes   287 Mbits/sec
> [  5]  46.00-47.00  sec  33.8 MBytes   283 Mbits/sec
> [  5]  47.00-48.00  sec  7.12 MBytes  59.8 Mbits/sec
> [  5]  48.00-49.00  sec  97.4 MBytes   817 Mbits/sec
> [  5]  49.00-50.00  sec  13.6 MBytes   114 Mbits/sec
> - - - - - - - - - - - - - - - - - - - - - - - - -
> [ ID] Interval           Transfer     Bitrate
> [  5]   0.00-50.00  sec  55.7 GBytes  9.57 Gbits/sec                 
> receiver
> -----------------------------------------------------------
> Server listening on 5201 (test #3)
> -----------------------------------------------------------
> 

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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