[Linux-aus] Request for Qualified Opinion: netperf, iperf, others

[Steve Walsh]

On 25/07/17 14:52, Arjen Lentz via linux-aus wrote:
> Yea so many of us in the real world have to deal with such low bandwidth all the time.
> I know you're spoilt at work ;-)
>
> And this is indeed the issue.
> Both tools and considerations will differ for different speeds of network.
> Also tuning of course, what's good tuning advice a machine on a highspeed network can easily cause low performance on a lower speed network.

Believe it or not, the link speeds I work with are anywhere from a
20Mbps metroE link from a third party service aggregator right up to
100Gbps (or higher) or so backbone link. And yes, you're right, there is
no tried and true tuning to rule them all, it requires knowledge of the
hardware and technology behind the link between the sites as much as the
hardware on the link between the switch and the device to determine the
best tuning for each host. One change on the link and you get to go back
and start again.

> I think so, yes - mostly.
> And I care about links that aren't managed by me, because I need to rely on them.
>
> You neatly described the specific ESnet needs. Similarly, perfSONAR is a wonderful project that enables research organisations globally to keep an eye on their networks.
> But neither deal with the reality that most of us poor sods operate in (even professionally), which is hosted machines and users who operate from mobile, ADSL or various types of NBN connections at widely different bandwidth rates. In addition, serious testing can require moving lots of data around, which again can be a problem with many connection plans which have data limits and/or costs.
> It's an interesting problem space.

What might be a good place to start is with something like Smokeping
[0], which allow you to test and graph latency to various hosts. We used
this recently to discover and confirm a power saving feature on mac
laptops that was driving people on a wifi network mental with poor
performance, and we've used it to monitor the quality of both intra and
inter city and national links.

regards

[0] http://oss.oetiker.ch/smokeping/index.en.html

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