[Pharo-dev] Spotter shortcut reset

Ben Coman btc at openinworld.com
Sun Feb 3 10:58:22 EST 2019


On Sun, 3 Feb 2019 at 23:25, webwarrior <reg at webwarrior.ws> wrote:

> 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 exactly like they should. When bandwidth -> 0,
> time
> -> +infinity.
>

Hey! Thanks for that reality check.
100kb ==> 515s
10kb ==>  5149s
duh! makes perfect sense.  I was sure I had checked that simple scaling
and it had been out by another magnitude, but I must have had a screw loose
from being too caught up in the graph.
It was just meant to be a prelude baseline before playing with random
packet loss.
Sorry for the noise.

cheers -ben
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