Useful Consumer Review

I’ve got a computer in the kitchen (as one does), but it’s very difficult to get Ethernet

cabling to where it’s at.  So I’ve been using a Devolo dLAN Highspeed Ethernet II home plug network-via-powerline plug.

And it totally sucks.  Sure, it’s slow, but worse is the latency and unreliability.  I’m using it for NFS stuff, and it’s just too crappy for words.

The throughput is pitiful, but it’s acceptable.

[larsi@stories ~]$ scp 07112011002.mp4 sparky:/tmp
07112011002.mp4                               100%  105MB 535.1KB/s   03:21

But the  latency is crappy:

[larsi@stories ~]$ ping sparky
PING sparky.gnus.org (80.91.231.5) 56(84) bytes of data.
64 bytes from sparky.gnus.org (80.91.231.5): icmp_req=1 ttl=64 time=29.0 ms
[…]
64 bytes from sparky.gnus.org (80.91.231.5): icmp_req=14 ttl=64 time=3.24 ms
64 bytes from sparky.gnus.org (80.91.231.5): icmp_req=15 ttl=64 time=4.59 ms
^C
— sparky.gnus.org ping statistics —
15 packets transmitted, 15 received, 0% packet loss, time 14020ms
rtt min/avg/max/mdev = 2.524/8.827/29.004/8.068 ms
So before I went all drill-ey with the Ethernet cabling, I thought I’d try a different poweline model — the Netgear Powerline 200 Mbps Nano Adapter (XAVB2101 (phew)).

And look:

[larsi@stories ~]$ scp 07112011002.mp4 sparky:/tmp
07112011002.mp4                               100%  105MB   3.5MB/s   00:30

It’s like a lot faster!  7x better throughput.  The latency is kinda similar, but more even:

[larsi@stories ~]$ ping sparky
PING sparky.gnus.org (80.91.231.5) 56(84) bytes of data.
64 bytes from sparky.gnus.org (80.91.231.5): icmp_req=1 ttl=64 time=11.7 ms
64 bytes from sparky.gnus.org (80.91.231.5): icmp_req=2 ttl=64 time=9.04 ms
[…]
64 bytes from sparky.gnus.org (80.91.231.5): icmp_req=12 ttl=64 time=3.36 ms
^C
— sparky.gnus.org ping statistics —
12 packets transmitted, 12 received, 0% packet loss, time 11016ms
rtt min/avg/max/mdev = 3.353/7.262/11.787/2.470 ms
So…  it’s better, but it’s not…  good.  A max latency of 11ms, compared to the max latency of 29ms of the Devolo.

Anyway, the comparison isn’t really fair.  The Devolos are a couple years old, so they’re previous generation tech.  But it does mean that if you’ve got old powerline gear, and you want slightly less crappy performance, you may consider buying new gear.

Book!

I have literally no idea why I might have ordered this book, but I’m unpacking stuff.  And just look at this cover:

That’s just totally fabulous.  And the book feels fantastic.  I want to read it right now!  But I’m not going to.  Probably next week.

Note To Self

This is how you set up the digitemp device the next time the SSD breaks down and you’ve forgotten to back up the /etc directory:

[larsi@stories ~]$ cat /etc/udev/rules.d/20-digitemp.rules
ATTRS{idVendor}==”0403″, ATTRS{idProduct}==”6001″, MODE=”0666″, NAME=”digitemp”

It’s “ATTRS” now, not “ATTR”.  Or “SYSFS”.  Thanks a lot, udev people.  Changing the names to be used in the conf files all the time really helps.  A lot.  Thanks.

stories:~# digitemp_DS9097U -s /dev/digitemp -i -c /etc/digitemp.conf
DigiTemp v3.5.0 Copyright 1996-2007 by Brian C. Lane
GNU General Public License v2.0 – http://www.digitemp.com
Turning off all DS2409 Couplers
..
Searching the 1-Wire LAN
2815ECE002000053 : DS18B20 Temperature Sensor
ROM #0 : 2815ECE002000053
Wrote /etc/digitemp.conf

Now we have a conf file, so we can use the device:

[larsi@stories ~]$ digitemp_DS9097U -q -c /etc/digitemp.conf -a
Jun 28 13:55:11 Sensor 0 C: 23.81 F: 74.86

Couldn’t be simpler.

Useful Consumer Review

I’m going to the Kongsberg Jazz Festival this weekend, but the schedule on Saturday is the weakest it’s been in years.  So we thought we’d do a micro-hackathon.  And then I needed a laptop with functioning built-in 3G. 

And I needed a new one for work purposes, anyway.  I’d never use it for anything but work.  It’s a work laptop.  Not a Gnus hacking laptop.  Nuh-uh.  So there.

So I got this Lenovo Carbon X1, because it has a trackpoint mouse thing.  I hate trackpads.  I installed Fedora 19 on it, and everything basically worked, except the 3G.  Naturally.

But after duckduckgoing (that verb should be shortened) a bit, I found the cause and the solution.

Apparently, the 3G cell phone thing doesn’t support something called “nbim”:

[larsi@building ~]$ lsusb
Bus 003 Device 002: ID 0bdb:1926 Ericsson Business Mobile Networks BV 







This is fixed by this tiny conf file:

[larsi@building ~]$ cat /etc/modprobe.d/avoid-mbim.conf
options cdc_ncm prefer_mbim=N

Reboot, and then it just worked.

So now I’m installing bzr Emacs and git Gnus, and then I’m ready to go.  Hopefully some Gnus bugs will be closed on Saturday.  If the amount of beer at the hackathong is just right.