Experiment using utahddc and uky

[Raj Thakkar]

Hello,

                 I was trying an experiment of file transfer using the resources from utahddc and uky using stitcher, but the throughput i am getting is not that good. I have tried this experiment before and the throughput was allright. Is there any upgrade going on in any of the resources used in the experiment.

Resources used
utahddc-ig

uky-pg

User

urn=urn:publicid:IDN+ch.geni.net+user+kbx429

Slice name: nyuky

Thank you

Regards

Raj Thakkar

[Aaron Helsinger]

You didn't say what throughput you are getting, or what you requested. But note that as of Omni2.5, the capacity you request defaults to 20MBps. You can change this with a commandline argument to stitcher, --defaultCapacity. See README-stitching.txt

Aaron

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[Raj Thakkar]

Thank you Aaron for the reply. I was transferring a 50mb file and the throughput i am getting is 0.084 MB/s. The attached screenshot is from the experiment i performed displays the transfer time in secs and throughput when i transfer 50mb file.

Thank you

Regards

Raj Thakkar

 

[Leigh Stoller]

> Thank you Aaron for the reply. I was transferring a 50mb file and the throughput i am getting is 0.084 MB/s. The attached screenshot is from the experiment i performed displays the transfer time in secs and throughput when i transfer 50mb file.

Hi It would be helpful if you also provided precise instructions
to duplicate your test.

Leigh

[Raj Thakkar]

Hello Leigh,

                      I was trying to send a 50mb file from one node to another using python and calculate the transfer time and throughput. I tried this experiment using nodes from utahddc and uky, Sending files from utahddc to uky and I got the results which I mentioned in previous email. So is there any updates going on in any of resources. Because I have tried this experiment using python code on different resources and I got throughput more than 7MB/s.

Thank you

Regards
Raj Thakkar

[Sarah Edwards]

Hi Raj,

Can you send us:

 * The RSpec for your setup

 * The name of your slice

 * The output of running iperf [1] on the links of interest

Thanks,

Sarah Edwards

[1] If you don't know how to run iperf, step 5.2 in our intro tutorial should explain it. See here: http://groups.geni.net/geni/wiki/GENIExperimenter/Tutorials/GettingStarted_PartI/Procedure/Execute#a5.2Installanduseiperf

*******************************************************************************

Sarah Edwards

GENI Project Office

BBN Technologies

Cambridge, MA

phone:    (617) 873-2329

email:    sedw...@bbn.com

[Raj Thakkar]

Hello Sarah,
                      

                           The iperf output and the rspec used for the experiment is attached with this e-mail. The slice name for the experiment is nyuky. The user detail is urn=urn:publicid:IDN+ch.geni.net+user+kbx429

Thank you

Regards

Raj Thakkar

[Sarah Edwards]

Hi Raj,

I setup the same stitched topology that you have (except that I made the raw-pcs into xen nodes; see attached for rspec) and ran iperf and I get very different results than you did although still not what I would expect.

I get the following:

sedwards@pc-1:~$ iperf -s

------------------------------------------------------------

Server listening on TCP port 5001

TCP window size: 85.3 KByte (default)

------------------------------------------------------------

[  4] local 192.168.1.1 port 5001 connected with 192.168.1.2 port 60957

[ ID] Interval       Transfer     Bandwidth

[  4]  0.0-10.2 sec  20.0 MBytes  16.5 Mbits/sec

pc-2:~% iperf -c 192.168.1.1

------------------------------------------------------------

Client connecting to 192.168.1.1, TCP port 5001

TCP window size: 23.5 KByte (default)

------------------------------------------------------------

[  3] local 192.168.1.2 port 60957 connected with 192.168.1.1 port 5001

[ ID] Interval       Transfer     Bandwidth

[  3]  0.0-10.1 sec  20.0 MBytes  16.6 Mbits/sec

I see two strange things:

 (1) I get much more bandwidth than you do but not the full 100 Mbps that is set in the RSpec which seems suspicious. I tried iperf both directions and tried longer data transfers (using -t) and always got something under 20 Mbps.  It looks to me like I got the default capacity of 20 Mbps instead of the 100Mbps specified in the request, but I don't know why.

 (2) The RSpec sets the image for one node and not the other.  Just as a general thing, it might be nice to set the image for both nodes so you know what you are going to get.

I'm not sure if anyone else can shed any light on the situation.

Sarah

[Aaron Helsinger]

When I try this, the full expanded request clearly says "100000" (in KBps) in all relevant spots for "capacity". So if some AM decided you only asked for 20000, then that is an AM error, not a stitching tool error. Of course, requested capacity is not the same as available actual capacity.

Aaron

<iperf -c uky.JPG><iperf -s utahddc.JPG><utahuky.rspec>

[Leigh Stoller]

> I setup the same stitched topology that you have (except that I made the raw-pcs into xen nodes; see attached for rspec) and ran iperf and I get very different results than you did although still not what I would expect.

If you can tell me which aggregates, I can take a quick look to
see if anything has a funky setting.

Leigh

[Raj Thakkar]

Thank you Sarah for the reply. I will try the experiment using the rspec. I will let you know what are the iperf results I am getting

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<iperf -c uky.JPG><iperf -s utahddc.JPG><utahuky.rspec>

[Sarah Edwards]

Leigh and Raj,

Luisa reminded me that if you only have one TCP flow in iperf on a xen VM then the bandwidth will max out at 20 Mbps. She says she doesn't see this with raw-pcs.

So I ran iperf again [1] with `-P 6` and got 96.7Mbps which sounds right and is consistent with Luisa's experience testing the racks.

Also Raj's RSpec connects utahddc and PG kentucky. He said his slice name was `nyuky`.

Hope this helps,
Sarah


[1] $ iperf -c 192.168.1.2 -t 60 -P 6
------------------------------------------------------------
Client connecting to 192.168.1.2, TCP port 5001

TCP window size: 23.5 KByte (default)
------------------------------------------------------------

[ 5] local 192.168.1.1 port 43484 connected with 192.168.1.2 port 5001
[ 3] local 192.168.1.1 port 43482 connected with 192.168.1.2 port 5001
[ 6] local 192.168.1.1 port 43485 connected with 192.168.1.2 port 5001
[ 8] local 192.168.1.1 port 43487 connected with 192.168.1.2 port 5001
[ 4] local 192.168.1.1 port 43483 connected with 192.168.1.2 port 5001
[ 7] local 192.168.1.1 port 43486 connected with 192.168.1.2 port 5001
[ ID] Interval Transfer Bandwidth
[ 8] 0.0-60.0 sec 120 MBytes 16.8 Mbits/sec
[ 4] 0.0-60.0 sec 120 MBytes 16.7 Mbits/sec
[ 7] 0.0-60.1 sec 115 MBytes 16.1 Mbits/sec
[ 5] 0.0-60.1 sec 120 MBytes 16.7 Mbits/sec
[ 3] 0.0-60.1 sec 105 MBytes 14.6 Mbits/sec
[ 6] 0.0-60.1 sec 114 MBytes 15.9 Mbits/sec
[SUM] 0.0-60.1 sec 694 MBytes 96.7 Mbits/sec

[Raj Thakkar]

The slice is expiring today. I tried  renewing sliver yesterday but it failed.  I am trying the experiment again with raw - pc's and will again check the iperf output.

Thank you

Regards
Raj Thakkar

[Nicholas Bastin]

On Thu, Apr 24, 2014 at 11:46 AM, Sarah Edwards <sedw...@bbn.com> wrote:

Luisa reminded me that if you only have one TCP flow in iperf on a xen VM then the bandwidth will max out at 20 Mbps.  She says she doesn't see this with raw-pcs.

The window size is way too small if you want single-flow throughput to be high, particularly given the latency in WAN connections (the resultant bandwidth delay product will be much too high for iperf's default window sizes).

You simply need to set the window size larger on both the server and client and your performance should be better for a single flow, regardless of raw-pc or xen VM. (The default raw PC window size is likely a lot larger, hiding this problem, but if you want deterministic performance from iperf you always need to set the window sizes you're going to use, otherwise it makes a guess at a default that is going to be highly intolerant of any latency in your connection).

Barring any other shaping going on, the throughput you're getting with a 23.5K window means you have a connection with roughly 12ms of delay.  To get 100 Mbits (or close to it) on this connection, you'd need a window size of 150K or larger (and make sure your buffer sizes on both end can support that large of a window).

--

Nick

[Leigh Stoller]

Excellent message Nick. May I suggest that we start a FAQ at the
top of geni-users (pinned), and that we start adding things like
this.

Question: “Why do I see poor bandwidth on my stitched links with iperf?”
Answer:

> The window size is way too small if you want single-flow throughput to be high, particularly given the latency in WAN connections (the resultant bandwidth delay product will be much too high for iperf's default window sizes).
>
> You simply need to set the window size larger on both the server and client and your performance should be better for a single flow, regardless of raw-pc or xen VM. (The default raw PC window size is likely a lot larger, hiding this problem, but if you want deterministic performance from iperf you always need to set the window sizes you're going to use, otherwise it makes a guess at a default that is going to be highly intolerant of any latency in your connection).
>
> Barring any other shaping going on, the throughput you're getting with a 23.5K window means you have a connection with roughly 12ms of delay. To get 100 Mbits (or close to it) on this connection, you'd need a window size of 150K or larger (and make sure your buffer sizes on both end can support that large of a window).
>
>

Leigh

[Brecht Vermeulen]

typically also handy in debugging link performance is to throw in an UDP
iperf to see what is possible on the links and when packet loss begins
to start:
server side: iperf -s -u
client side: iperf -c xxx -b 50M

so you can vary bandwidth and packet size and see what happens

Brecht

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[Raj Thakkar]

Thank you Nicholas for the reply. I will go ahead and look into Window size and include it in server and client