Re: [Iperf-users] iPerf Window size

[Kaliaperumal, Rajesh]

Thanks Bob. I will run some tests using iperf2.0.11 with the -e and –vary-load 
option.

I am trying to understand the impact on TCP performance with variation of 
window size.

Thanks and regards,
Rajesh K


From: Bob McMahon 
Date: Friday, May 25, 2018 at 1:54 PM
To: "Kaliaperumal, Rajesh" 
Cc: iPerf User Group 
Subject: Re: iPerf Window size

Here is a good starting link:  
https://fasterdata.es.net/host-tuning/linux/

Speaking for iperf2, the -w window size sets the socket buffer size.

There has been a lot of effort to reduce the windows per the buffer bloat 
problem.

What exactly are you trying to influence with TCP by adjusting the window sizes?

If you use iperf 
2.0.11
 with -e and --vary-load you can get an idea how the congestion window and the 
RTT are responding per the TCP offered load.

Bob


On Fri, May 25, 2018 at 1:39 PM, Kaliaperumal, Rajesh 
> wrote:
Hi all,
  Can anyone explain or point me to some documentation that explains 
how iPerf3 and iPerf2 handles the window size parameter?

I am trying to understand how to use this attribute for influencing the TCP 
performance.

Thanks and regards,
Rajesh K



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[Iperf-users] iPerf Window size

[Kaliaperumal, Rajesh]

Hi all,
  Can anyone explain or point me to some documentation that explains 
how iPerf3 and iPerf2 handles the window size parameter?

I am trying to understand how to use this attribute for influencing the TCP 
performance.

Thanks and regards,
Rajesh K


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Re: [Iperf-users] iPerf Window size

[Bob McMahon via Iperf-users]

Here is a good starting link:  https://fasterdata.es.net/host-tuning/linux/

Speaking for iperf2, the -w window size sets the socket buffer size.

There has been a lot of effort to reduce the windows per the buffer bloat
problem .

What exactly are you trying to influence with TCP by adjusting the window
sizes?

If you use iperf 2.0.11  with -e
and --vary-load you can get an idea how the congestion window and the RTT
are responding per the TCP offered load.

Bob



On Fri, May 25, 2018 at 1:39 PM, Kaliaperumal, Rajesh <
rajesh.kaliaperu...@arris.com> wrote:

> Hi all,
>
>   Can anyone explain or point me to some documentation that
> explains how iPerf3 and iPerf2 handles the window size parameter?
>
>
>
> I am trying to understand how to use this attribute for influencing the
> TCP performance.
>
>
>
> Thanks and regards,
>
> Rajesh K
>
>
>
>
>
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[Iperf-users] iperf 2.0.11 released

[Bob McMahon via Iperf-users]

Hi All,

We've just released iperf 2.0.11 tested across all supported platforms.
 Here are the significant changes:

2.0.11 change set (as of May 24th, 2018)
o support for -b on server (read rate limiting)
o support for --isochronous traffic with optional frames per second, mean
and variance uses a log normal distribution (requires configure
w/-enable-isochronous and compile)
o support for --udp triggers (requires configure w/ --enable-udptriggers,
early code with very limited support)
o support for --udp-histogram with optional bin width and number of bins
(default is 1 millisecond bin width and 1000 bins)
o support for  frame (burst) latency histograms when --isochronous is set
o support for --tx-sync with -P for synchonrized writes.  Initial use is
for WiFi OFDMA latency testing.
o support for --incr-dstip with -P for simultaneous flows to multiple
destinations (use case is for OFDMA)
o support for --vary-load with optional weight, uses log normal
distribution (requires -b to set the mean)
o support for --l2checks to detect L2 length errors not detected by v4 or
v6 payload length errors (requires linux, berkeley packet filters BPFs and
AF_PACKET socket support)
o support for server joining mulitcast source specific multicast (S,G) and
(*,G) for both v4 and v6 on platforms that support it
o improved write counters (requires -e)
o accounting bug fix on client when write fails, this bug was introduced in
2.0.10
o slight restructure client/server traffic thread code for maintainability
o python: flow example script updates
o python: ssh node object using asyncio
o python: histograms in flows with plotting (assumed gnuplot available)
o python: hierarchical clustering of latency histograms (early code)
o man pages updates
o Note: latency histograms require client and server system clock
synchronization.   A GPS disciplined oscillator using Precision Time
Protocol works well for this.

A 2.0.11 zipped binary for windows will be uploaded soon.  (We're
investigating cross compiling using MXE http://mxe.cc/#introduction to
simplify the release process)

Bob
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