Digital CoPilot is born


It's been a long time since I started this project - nearly 8 months of solid work - however its starting to get close to completion and the Digital CoPilot web site is now up and running!

My aims for this device is to be simple, user friendly, and a very handy tool in the quest to make aviation safer for everyone.

As with everything I do, any feedback is welcome :)

Xen, CPUFreq and the Core i5 CPU


A while ago I updated my main fileserver (which was an old P4!) to a new Intel Core i5 CPU & associated hardware. I've managed to do some more tweaking today and found some very interesting things.

All Intel i5 CPUs (and probably the i3 & i7 as well) have this feature called Intel Turbo Boost. In short, what this does is to make your CPU run faster when it needs to - and as long as it doesn't get too hot etc. This gives a nice performance boost without having to overclock the CPU all the time to squeeze out a little more performance.

There are however a few things you need to configure correctly to make sure Turbo Boost works on your system:

1) Configure cpuspeed to use the acpi_cpufreq module. Once this is done, have a look at scaling_available_frequencies. You should see something like this:

# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies 3326000 3325000 3192000 3059000 2926000 2793000 2660000 2527000 2394000 1197000

This tells us we can scale between 1197Mhz and 3325Mhz. Note the entry for 3326Mhz. This is the way linux shows us the Intel Turbo Boost functionality.

2) It's probably wise to use the ondemand governer for cpufreq. This will allow the system to ramp up its clock speed as required, then back it off automatically when things are a bit quieter.

3) Check to see that loads in Xen DomUs are correctly ramping up the CPU speed. To do this, I used this command:

watch "xm list; echo; cat /proc/cpuinfo | grep MHz"

This will show what DomU systems are running every 2 seconds, as well as the frequency that each core is running at. My system is currently an i5 661 (2 cores, 4 threads), so I see:

cpu MHz : 1197.000 cpu MHz : 1197.000 cpu MHz : 3325.082 cpu MHz : 3325.082

The last 2 entries are the hyperthreads for core0 and core1 respectively. You will note that the frequency of the extra threads do not change - but the cores will. When you do some activity in a DomU, you should see one or both of the cores clock up as required.

I love technology when it works properly :)

This Is True, Really!


It's over 10 years since This Is True, Really! (TITR) was around on an Internet Radio site called NetRadio. It was well worth it - and I still get a good chuckle when I happen to come across some old shows on my network. Sadly, I could find no trace of TITR or what happens to Scot Combs and Tony Vircenis - A long lost jockey is out there but all I can remember is that technically how you write his name is "You can't get potatoe salad a la carte".

So, for your listening pleasure - Click on to re-live some past glory :)

Telstra (Australia) vs Telecom NZ


Its interesting to note that in a recent letter to shareholders, Telecom NZ have almost confirmed that the company will be splitting into two distinct companies. One to manage the fibre optic infrastructure and another to offer retail/wholesale services. This is something that the Australian Government have been trying to force Telstra (however unsuccessfully) for quite a long time.

From the letter to shareholders:

Over the last couple of years a Government policy has evolved that is known as Ultra Fast Broadband. The aim of this policy is to invest $1.5 billion of public funds in extending the amount of fibre optic cables used to carry broadband in New Zealand.

... one of the requirements of the tender process is that the companies that build the fibre optic infrastructure do not also offer services to end users, such as retail and business customers.

This has made me wonder a number of things. Why didn't the NBN have a similar clause? Why have Telstra been so reluctant to do this?

For those that are interested, the full letter is available here.

How time flies.


It's been quite a while since I've posted an update on whats going on. Lots has changed since my last post too! This site (and the others hosted here) have been moved to a new server kindly donated by Andrew Van Slageren - which means the old dual P3 1Ghz with 1Gb of RAM has been replaced with a 1RU Dual Opteron 2.4Ghz with 7Gb of RAM. I had a few issues with the server running out of RAM(!), however a bit of tweaking over the past few days seems to have brought that under control.

In the phone world, I've moved on to a HTC Touch Pro 2. This is a fantastic phone. I did have an issue with the USB connector on the phone and had to send it in for a warranty claim, however it seems to be much better now. There are still a few minor issues with keyboard LED brightness on one key - I can live with that though. The stock ROM from HTC is pretty damn good - certainly a big step from back in the Hermes days where the stock ROMs were full of crud. I'm even liking WM6.5 - which was something I found VERY hard to do on the old Hermes - probably due to the lack of CPU/RAM on the older models.

I've started doing from night VFR for my flight training - however as the beginning of winter is rolling in it is making it difficult to get suitable days. Due to the height of the Melbourne CBD the cloud base needs to be 3100ft or heigher - which is rare right now.

I've also rejigged all my home systems to run on Xen in CentOS 5.5. I upgraded my old fileserver to an Intel Core i5 CPU which supports hardware virtualisation and now have many linux VMs and one Windows XP VM. Much more useful than running a single instance on a physical machine! I now have 1 PC for Asterisk (as it doesn't run in a VM well!), 1 PC for my VMs, 1 x Via CN1000 as my router (using a CF card as a HDD), my Mac Pro as my desktop, a Dell Inspiron 8600 as my girlfriends main system, and a new ASUS EEEPC 1005P as my netbook. I think this is the favourite setup I have ever had for computing!

Xen disk IO on linux RAID5 array.


I've been playing with Xen for quite a while - having everything virtual is a godsend - however when you hit performance problems it can be a nightmare. After recently following some guides on Xen DomU installation I noticed that performance in the Disk IO area was just horrible - so I did what anyone in my shoes would do and wrote a quick guide that will squeeze MUCH more performance out of your Xen installations than following many of the existing (and outdated) guides.

This method works so well because it keeps all blocks aligned on your RAID5 array. If you do things differently, then you will get multiple writes as parity is updated on your array causing a huge penalty to performance.

Head over to the Xen Performance Guide