Planet Linux Australia

Syndicate content
Planet Linux Australia - http://planet.linux.org.au
Updated: 3 min 1 sec ago

Mark Greenaway: Guitar

Mon, 2014-08-25 02:26
Does anyone still blog? It seems nearly everyone has moved onto Twitter/Facebook. I miss being able to express thoughts in more than 160 characters.



I went to a picnic recently, and some people were passing a steel string guitar around. I'm not a good acoustic player, but it was fun so I had a bash. Someone played Under The Bridge, and took liberties with the chord voicings. So I was inspired to pick up my guitar and work through the official transcription, which I own. While the basic form of the song is pretty simple, as you can hear, the clever part is the choice of chord voicings and fills. I'll be practicing that one for a while.



I've also started over working through the Berklee method books, starting at Volume 2. I learned by playing by ear and memorising, so sight reading is still something I'm getting used to, and sometimes I'm not disciplined enough to do it properly. But I'm getting better at that. I'll be so happy when I start to get good at position playing.

Mark Greenaway: Physiotherapy

Mon, 2014-08-25 02:26

I'm at Elevate in Sydney CBD. For a long time, I've struggled with flexibility issues, and I began to think something must be wrong. It turned out something is wrong-I have a minor skeletal deformity in my left hip joint, and my muscles have developed in a strangely imbalanced way to compensate. Except it isn't working, I have severely reduced range of motion and had chronic pain in my left hip joint.

My Physio thinks he can correct the problem, but it's going to take a while. So I'll be off training for at least six weeks, and more likely two months or more. But it will be worth it if my joint pain goes away and I can move like the other people my judo class.

Posted via LiveJournal app for iPhone.

Mark Greenaway

Mon, 2014-08-25 02:26
"Curiously enough, the only thing that went through the mind of the bowl of petunias as it fell was 'Oh no, not again.'" - Hitchhiker's Guide to the Galaxy.

Mark Greenaway: One for the stats nerds

Mon, 2014-08-25 02:26
At USyd, we did all our stats in R. Now I'm working at the Department of Health, and we do most of our stats in SAS. SAS is pretty different to R, and so I've needed to work hard to try to learn it.



This is a rite of passage that most trainee biostatisticians go through, and so people have shoved various books into my hands to help me get up to speed. I'll omit the names of many of the books to protect the guilty, but the most useful book someone pressed innto my hands was The Little SAS Book, which I read cover to cover in two sittings.



The Little SAS Book is more technical than the others, hence more suitable for programmers, and actually gives you an inkling of what the designers of the language were thinking. That's helped me begin to think in the language, which is something none of the other books have helped me to do.



The best comparison I can come up with for now is that SAS is like German, whereas R is like Japanese. SAS has lots of compound statements, each of which does a lot, while R has many small statements which each do a little bit. So would you like to be able to speak German or Japanese? The correct answer is, of course, both, each at the appropriate time :)

Mark Greenaway: Gainfully employed

Mon, 2014-08-25 02:26
A while ago, I applied for a job as a biostatistician in public health. I made it to the interview stage, and that seemed to go quite well. They said they'd contact me in seven to ten days. I didn't hear anything for a while, but eventually I bumped into one of my referees who said he'd spoken with my interviewers, and they sounded "very positive". I poked my other referee, and he said they'd spoken to him too. So that was sounding pretty good.



On the advice of my girlfriend, I asked them how things were going, and they said they were waiting for a criminal record check to complete. Owing to my misspent youth, there's no criminal record to check, so now I was feeling very positive indeed. To cut a long story short, today they offered me a position, and I accepted.



So all's well that ends well!

Mark Greenaway: British Medical Journal publishes paper on the risks of head banging

Mon, 2014-08-25 02:26
Head and neck injury risks in heavy metal



This is the funniest thing I've seen in ages. I particularly like the mitigation options: many injuries could be prevented if AC/DC would stop playing Back In Black live, and instead play Moon River ;)

Mark Greenaway

Mon, 2014-08-25 02:26
Sometimes I feel like I'm not so much in control of my body as sending it memoes. And it responds with things like "Tough job, hip rotation. Can you come back Monday?".

Mark Greenaway: True Temperament

Mon, 2014-08-25 02:26
I've been playing a few more jazz chords and moveable chord forms of late, and my ear's been getting a little better. Unfortunately, this means I've become more sensitive to how out of tune the notes in some of those chords sound as you move up the neck.



To some extent, this problem is inherent in the guitar's construction. There are some very determined people at a company called True Temperament who've decided to do something about this by making custom necks with strange looking curved frets. The FAQ on that site also goes into some depth about tuning methods and why the problem is unsolvable on a standard guitar.



So I'm going to have to live with it, or pick up a saxophone or something :)

Mark Greenaway: Judo

Mon, 2014-08-25 02:26
Judo is going well. I've been working on the fundamentals a lot recently, especially breakfalling. I'm finally getting to the point where I'm losing my fear of being thrown - the people in my club are nice and aren't there to hurt people, and I've learnt that by just going with the throw rather than resisting you can breakfall more cleanly. That way, you're very unlikely to get hurt. And if you pay attention while you're being thrown, you tend to learn more about how the throw works, so when it comes your turn, you'll do it better.



Being a lightweight, I've got to fight differently to the heavier judoka, so in the next little while I'm going to focus on improving my speed and perfecting my technique for the basic throws and sweeps. If you're stronger you can just apply more force to get bad throwing techniques to work, but this isn't an option for me. I think ultimately it's a good thing, because I'll have to learn the throws properly.



Always more things to work on. Practice, practice, practice.

Mark Greenaway

Mon, 2014-08-25 02:26
Having spent the last few weeks being sick, now that I'm beginning to get better I'm finding I'm pretty hyper.

Mark Greenaway

Mon, 2014-08-25 02:26
Just getting over this illness, whatever it is. I just want to eat and sleep.

Mark Greenaway

Mon, 2014-08-25 02:26
I'm using a surprising amount of maths in my current job. Recently, we've been trying out measures of diversity. Today, I'm taking a look at Shannon entropy.

Mark Greenaway: The tyranny of distance

Mon, 2014-08-25 02:26
At the moment, I'm commuting between two and two and a half hours each way to and from work. That's between twenty and twenty five hours a week. And it's costing me more than $65 a week to do all that travelling. This doesn't make any sense. So looking forward to moving.

Mark Greenaway

Mon, 2014-08-25 02:26
I've been sick for a few weeks. I thought it was a bad cold, but my mum thinks it's something more serious. She suggests it might be sinusitis. We're not doctors, so it's off to visit a GP tomorrow to find out what's wrong.

Tim Connors: An open letter to Peter Ryan regarding police treatment of cyclists

Mon, 2014-08-25 02:26
Hon Peter Ryan,



I am writing because I am concerned at the number of recent incidents where a driver has collided with a cyclist, and the case hasn't been followed up by the police. Such incidents and the publicity surrounding them does nothing to encourage road users to obey the law when they realise that they will most likely get away with not doing so.



A week ago in Ballarat, a 13 year old boy was hit by a car, and the police said the boy had the right of way[1]. Despite this, the article linked states that the police will not charge the driver. This, despite her having broken Australian Road Rule 67 to 72, 84 or 86 depending on circumstances at the stated intersection, or perhaps 140 to 144 if travelling in the same direction. She was likely negligent in allowing the collision to happen in the first place, which, by my understanding, is a criminal offence, especially since there was serious injury involved. If she used the usual excuse that "she didn't see him", then that's an admission of guilt in failing to obey ARR 297 - driver having proper control of vehicle.



Also recently, there was a highly publicised case where Shane Warne had an altercation with a bicycle rider. In that case, the fact that Warne hit the cyclist from behind (ARR 126) after overtaking unsafely (ARR 144) is undisputed[2]. The fact that details were not exchanged following the collision is also undisputed (ARR 287). It is also well established that Warne was stopped unnecessarily in a bike lane (ARR 125; 153)[3]. And yet the police will not investigate[4].



Going back a number of years, I also have not had good experiences getting the police to follow up on cases. In my most recent case (11/10/2005; I do not know the case number sorry, all I know was that I was attended to by Angove & Auchterlonie from Boroondara police), the driver also failed to obey ARR 287 (as well as a slew of other offences, such as ARR 46 and 148 - changing lanes without indicating sufficiently and without due care). The police refused to prosecute the driver, and also would not hand over the driver's details or insurer details, based on some misguided privacy policy, asking me instead to fork out for a freedom of information request. Given that I was a broke student at the time, this was not a feasible thing to do and I never did receive compensation from the driver for damage to my bicycle, clothes, and large out of pocket expenses for travel to medical care for several years that the TAC didn't cover. The police also displayed a lack of knowledge of the law, initially thinking that I had broken ARR 141.



I can't imagine why the police aren't investigating these cases, because in each case, clear evidence is at hand, and not disputed. The identities of all parties are known. It should be an open and shut case. Without the police making charges, the rider in each case will have a much harder time claiming from the driver's insurance (if the boy was not admitted overnight, his TAC excess will be an enormous burden to his family). The driver in each case will not be discouraged from driving in a similar fashion next time. And other drivers also know that they will most likely get away with any offences they commit if a bicycle is involved. This is a perverse reversal of the situation that we should have, in which drivers should be encouraged to take due diligence around cyclists. It almost seems that the police always assume a cyclist is at fault unless proven otherwise in Australia, whereas most other countries with an established bicycling culture assume that the driver is at fault unless proven otherwise as they hold the burden of driving the more deadly vehicle and so should be required to take due care.



If the laws weren't adequate enough to prosecute to the driver in the above cases, has your department been contacted to update the laws, and what is being done? Keep in mind that cyclists have no protection other than by the law, and as the more vulnerable road user, the laws should focus on their safety and ensuring that transgressions are dealt with effectively.



Can you please encourage the police in each of these cases to follow them up to the full extent that the law currently allows.





Sincerely,





[1]

http://www.theage.com.au/victoria/teen-cyclist-struck-by-car-20120110-1ps85.html



[2]

http://theage.drive.com.au/motor-news/warnes-tirade-triggers-bike-rego-call-20120118-1q5k0.html



[3]

http://www.cyclingtipsblog.com/2012/01/cyclist-versus-warnie-the-cyclists-story/



[4]

http://www.heraldsun.com.au/news/more-news/warne-blasts-cyclists-on-twittershane-warne-clashes-with-cyclist-on-way-home-from-training-session/story-fn7x8me2-1226246735306

Tim Connors: Breaking windows

Mon, 2014-08-25 02:26
Another letter in The Age today. Unedited text below:





Ian Porter (Without car manufacturing, we are on the road to ruin, The Age, 13 Jan) believes that the government needs to keep throwing money at the car industry in order to support other industry in Australia. I'm surprised as an industry analyst, he hasn't heard of the broken window fallacy.



Throwing good money after a bad unsustainable industry that can't adapt is just a waste. It's exactly identical to sending soldiers to dig holes only to fill them back up again just to keep them employed and off the streets. The money could be better spent on doing useful things that will remain useful into the future. Yes, paying people to break windows and then paying the glazier to repair them will keep people employed, but couldn't the glazier be better employed building things that then keep other people employed into the future?



Why don't we do something useful with the money instead? Like built modern intra- and inter-city rail infrastructure? This won't become stranded assets when cheap oil becomes unavailable. We won't be left with vast tracts of useless motorways - we will continue to be able to use the rail infrastructure well past these boom times.

Tim Connors: Police a bit rich

Mon, 2014-08-25 02:26
Hrrrfm. The Age didn't publish my letter:





I find it a bit rich that the police union are upset that information

alongside a photograph was distributed about one of their members, without

his consent. I understand that truth is not not considered a defence to

libel in Australia, so it was perhaps unwise to distribute such a photo.

But it is common police practice to photograph protesters without our

consent, and to store these photos with profiles in national databases

without a right of appeal or review. I probably find myself on some

watchlist now just for attending some of last night's Occupy Melbourne

general assembly.



Maybe there would be no need for a photograph to be distributed if police

correctly wore their own name badges (and if the name badges weren't

deliberately too small to read). Or if there was some accountability, as

opposed to the protectionism that police have demonstrated in the past

with the likes of their disgusting behaviour at the APEC protests.

Tim Connors: on the hardships of living with minimal amounts of RAM (4GB or so)

Mon, 2014-08-25 02:26
I just got 200MB/s read/write rate from my swap device on my laptop. Fast laptop eh? OK, so I'm cheating by using the compcache/zram module from the staging tree.



When I bought my 2 laptops, I was upgrading from 256MB to 4GB. I thought that would be enough to last me for years. The video card on that first laptop came with more memory than the system memory of the machine I was upgrading from. Alas, I forgot to factor in opera and firefox (we're now in the era when Emacs is officially lightweight). And being laptops with the particular chipsets they have, 4GB is it, I'm afraid.



And the fact that Linux's VMM, for me, has never really handled the case of a machine running with a working set not all that much smaller than physical RAM. If I add up resident process sizes plus cache plus buffer plus slab plus anything else I can find, I always come up about 25% short of what's actually in the machine. Ever since those 256MB days (whereas about half the ram went "missing" on the 128MB machine prior to then). And even when your working set, including any reasonable allowance for what ought to be cachable, falls far short of RAM, it still manages to swap excessively, killing interactive performance (yes, I've tried /proc/sys/vm/swappiness). When I come in in the morning, it's paged everything out to make backups through the night marginally faster (not that I cared about that - I was asleep). Then it pages everything back in again at 3MB/s, despite the disk being capable of 80MB/s. Pity it's not smart enough to realise that I need the entire contiguous block of swapped pages back in, so it might as well dump the whole wasted cache, and read swap back in contiguously at 80MB/s rather than seeking everywhere and getting nowhere.



What I really wanted, was compressed RAM. Reading from disk with lots of seeks is a heck of a lot slower than decompressing pages in RAM. I vaguely recall such an idea exists if you're running inside VMWare or the like. But this is a desktop. I want to display to my physical screen without having to virtualise my X11 display.



But the zram module might be what I want. Pretty easy to set up (in the early days, it required a backing swap device and was kinda fiddly). Here's the hack I've got in rc.local along with a reminder sent to myself that I've still got this configured, at reboot:

echo 'rc.local setting zramfs to 3G in size - with a 32% compression ratio (zram_stats), that means we take up 980M for the ramfs swap' | mail -s 'zram' tconnors echo $((3*1024*1024*1024)) > /sys/block/zram0/disksize mkswap /dev/zram0 swapon -p 5 /dev/zram0

It seems to present as a block device of default 25% of RAM size (but I've chosen 3GB above), and as you write to that device, compressed versions of the page end up in physical memory. Eventually you'd run out of physical memory, and hopefully you have a second swap device (of lower priority) configured where it can page out for real. In my case, I'm using the debian swapspace utility. Be warned, if you plan to hibernate your laptop, not to forget to have a real swap partition handy :)



zram_stats tells me I'm currently swapping 570MB compressed down to 170MB, for a compression ratio of 28%. That 170MB has to be subtracted from the memory the machine has, so it appears to really only have 3.8 or so GB. No huge drawback. At that compression ratio, if I were to swap another 3GB out, physical ram stolen by zram would only be 1GB. My machine would be appearing to have 3GB of physical ram, 3GB of blindingly fast swap, and a dynamic amount (via swapspace) of slow disk based swap. I'd be swapping more because I had 1GB less than I originally had. But at least I'd be swapping so quickly I ought not notice it ('course, I haven't bench marked this). And I'd be able to have 2GB more in my working set before paging really starts to become unbearable.



So, with an uptime of 4 hours, I haven't even swapped to disk yet (I know this, because swapspace hasn't allocated any swapfiles yet). The machine hasn't yet thrashed half to death yet. That must be a recent record for me.





Yes, the module is in the staging tree. It's already deadlocked on me once, getting things stuck in the D state. And the machine has deadlocked with unexplained reasons a couple of other times recently (with X having had the screensaver going at the time, so no traces, and no idea whether it's general kernel 3.0 flakiness or zram in particular; I had forgotten until tonight that I even had previously configured zram back in the 2.6.32 days).



What I really *really* want, since I lack the ability to add more ram to the machines, is a volatile-ram ESata device, used purely as a swap device, reinitialised each boot (ie, having a battery backup is just pointless complexity and expense, and SSD is slow, fragile and prone to bad behaviour when you can't use TRIM, for the amount of writes involved in a swap device). There is the Gigabyte i-Ram and GC-RAMDISK and similar devices, but they're kinda pricey, even without the RAM included in the price. Why is SSD so much cheaper than plain old simple RAM these days? I thought the complexity involved would very much make it go the other way around.



What I really *really* **really** want, is for software to be less bloaty crap.

Tim Connors: We do things differently, here

Mon, 2014-08-25 02:26
Another slightly edited letter published in The Age today. Maybe I should become a media mogul. Original here:



I've just come back from a tour of Europe. Wind farms are everywhere. Near tourist attractions, and along roads where it is particularly windy. Anywhere appropriate, and especially near townships and individual houses, because that's where the consumers of electricity are. No one seems to have a problem with them. People there don't suffer from increased rates of cancer or bogus self-imagined inflictions. They don't ban building windmills within 2km of towns. They don't ban the building along a windy stretch of road because tourists happen to drive along there.



They also don't develop in green wedges, allow cattle to graze in their national parks, or try to make it easier to log old growth forest and make it harder to protect such lands.



Europeans seem to have no problem accepting that, despite their per-capita emissions being way below ours, that something has to change. It's a pity we are not lead by leaders. The best I can manage out of my local member, Ted Baillieu, is a form letter in reply to my concerns, uttering vague niceties about planning and the economy, and attacking the opposition.

Tim Connors: Failed and now discarded Victorian cycling strategy

Mon, 2014-08-25 02:26
I've always been a crazy cat man who sends letters to the editor and his local parliamentary representitatives. Except that I have no cat. Anyway, a shortened version of this letter was published in The Age today.





Dear Sir/Madam (CCed my State local member, and The Age letters),



The auditor general's report into the Victorian government cycling strategy said "the Department of Transport and VicRoads had not ... addressed conflicts and delays where cyclists crossed busy roads, and where cyclists and pedestrians shared paths." ("No way to spin it, the wheels are off", The Age, Aug 18). It's not just busy crossings that cause unnecessary delays to people not in the precious car.



A trip along Southbank is usually hampered by 2 traffic light controlled crossings where up to 100 pedestrians and riders are waiting at the lights with an average waiting time of around 5 minutes between them. That's 10 minutes per return trip wasted. We wait for just an occasional car (each with just one person in them) and empty tram to pass. The cars are frequent enough to make running ("jaywalking") across the road a little unsafe, but not frequent enough that the road is anywhere near capacity and that adding more frequent red lights for the car traffic is going to harm the flow into and out of the city at all. And it will help the 100 waiting pedestrians.



In the land where cycling is taken seriously, Holland, they want cyclists to have to wait no more than 15 seconds. And they're experimenting with microwave sensors to extend the green cycle to let cyclists cross safely. Here, the Southbank story is repeated across the city. Outside Swinburne University, a pedestrian light regularly sees several dozens of students wait several minutes at lunchtime to cross while a small handful of cars (each with just one person in them) cross just frequently enough to make a quick dash across the road down from the lights, impossible. The vehicle sensor loops at Camberwell Junction have, for years, been tuned to not even be sensitive enough to detect cyclists, so you can wait at 11pm for 2 cycles of the lights to completely bypass turning green on the road you're travelling on, while no cars cross the other legs of the junction at all before you give up and cross illegally (completely safely, because there's no traffic at all at that time of night and you can see for miles).



Given that you can't continue to keep encouraging people to get in their cars because it's been conclusively proven over the last 40 years that you can't build your way out of car congestion, perhaps it time to promote other forms of travel?