[Pharo-dev] Spotter shortcut reset

webwarrior reg at webwarrior.ws
Sun Feb 3 10:24:30 EST 2019


Ben Coman wrote
> On Sat, 2 Feb 2019 at 18:54, ducasse <

> stepharo@

> > wrote:
> 
> ...
> 
> 3. Ticked "Free tier only" filter.
> + Selected "Amazon Linux 2 AMI (HVM), SSD Volume Type"
> + Clicked 
> <Review and Launch>
>   (used default t2.micro)
> + Clicked 
> <Launch>
> + From the pull-down selected "Create a new key pair",
> gave it a name and clicked 
> <Download Keypair>
>  saved as
> "SydneyPharoSpeedTest.pem"
> + Clicked 
> <Launch Instance>
> + Clicked 
> <View Instances>
> noted instance...
> * IP address: 54.252.136.78
> * Zone: ap-southeast-2b
> * Security Group: Launch Wizard 1
> 
> 4. On my Windows 10 box, in WSL did...
> $ cd ~/.ssh       # if it doesn't exist, first do...   mkdir -m 700 ~/.ssh
> $ cp /mnt/c/Users/Ben/Downloads/SydneyPharoSpeedTest.pem   ~/.ssh
> $ chmod 400 ~/.ssh/SydneyPharoSpeedTest.pem
> $ ssh -i ~/.ssh/SydneyPharoSpeedTest.pem  ubuntu at 54.252.136.78$ cat
> /etc/os-release
> ID="amzn"
> ID_LIKE="centos rhel fedora"
> 
> 
> GOOD NETWORK BASELINE TEST...
> Ignoring any packet loss on poor networks, first testing low bandwidths on
> a good network
> $ vi test.sh
> #!/bin/sh
> if [ -d out ]; then
>     dirdate=`stat -c %z out | awk '{print $1"-"$2}' `
>     mv out out.${dirdate}
> fi
> mkdir out
> for RATE in 1000k 500k 200k 100k 50k 20k 10k 5k 2k 1k
> do
>   echo $RATE
>   /usr/bin/time -f "%e" -o out/time.$RATE \
>        wget --quiet --limit-rate $RATE
> https://files.pharo.org/pharo-launcher/1.6/pharo-launcher-1.6.msi -O
> out/file.$RATE &
> done
> 
> $ sh test.sh
> monitoring with...
> $ cat out/time* | sort -n
> $ ls -lS out
> 
> results in following table and graphs...
> $RATE
> (kb/s) TIME
> (s) TIME
> (min) TIME
> (hr)
> 1000 54 1 0.0
> 500 105 2 0.0
> 200 259 4 0.1
> 100 515 9 0.1
> 50 1029 17 0.3
> 20 2576 43 0.7
> 10 5149 86 1.4
> 5 10527 175 2.9
> 
> [image: download-speed.png]
> 
> Wow that surprised me.  I'm not sure what the behaviour of file servers at
> low bandwidth should be,
> but intuitively the above seems odd.  In the past troubleshooting seems to
> have been
> focused on the cause of slow speeds, but these can occur for many reasons
> unrelated to the
> the file server.  The above test ignores cause to isolate behaviour at
> slow
> speeds.
> 
> I forgot my own download speed yesterday (today is okay), but here is
> another sample...
> "(in Argentina) it is really slow ... 3.5KB/s ... average 10KB/s".
> http://forum.world.st/Pharo-Downloads-are-sluggish-td5084963.html
> 
> I would hope that download time was near linear with speed all the way
> down
> to 1kb/s.
> Anyone have some sysadmins they can lean on to understand if that is
> realistic?
> 
> The straightness of the line using a log-log axis makes it seem like
> policy
> rather than physics.
> [image: download-speed(log).png]
> 
> HTH,
> cheers -ben
> 
> 
> download-speed.png (39K)
> <http://forum.world.st/attachment/5094677/0/download-speed.png>
> download-speed(log).png (34K)
> <http://forum.world.st/attachment/5094677/1/download-speed%28log%29.png>

Why does that surprise you?

Download time [s] = amount of data [B] / bandwidth [B/s].
Your data and graphs look exatly like they should. When bandwidth -> 0, time
-> +infinity.




--
Sent from: http://forum.world.st/Pharo-Smalltalk-Developers-f1294837.html



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