Recent blog entries for etbe

Swap Space and SSD

In 2007 I wrote a blog post about swap space [1]. The main point of that article was to debunk the claim that Linux needs a swap space twice as large as main memory (in summary such advice is based on BSD Unix systems and has never applied to Linux and that most storage devices aren’t fast enough for large swap). That post was picked up by Barrapunto (Spanish Slashdot) and became one of the most popular posts I’ve written [2].

In the past 7 years things have changed. Back then 2G of RAM was still a reasonable amount and 4G was a lot for a desktop system or laptop. Now there are even phones with 3G of RAM, 4G is about the minimum for any new desktop or laptop, and desktop/laptop systems with 16G aren’t that uncommon. Another significant development is the use of SSDs which dramatically improve speed for some operations (mainly seeks).

As SATA SSDs for desktop use start at about $110 I think it’s safe to assume that everyone who wants a fast desktop system has one. As a major limiting factor in swap use is the seek performance of the storage the use of SSDs should allow greater swap use. My main desktop system has 4G of RAM (it’s an older Intel 64bit system and doesn’t support more) and has 4G of swap space on an Intel SSD. My work flow involves having dozens of Chromium tabs open at the same time, usually performance starts to drop when I get to about 3.5G of swap in use.

While SSD generally has excellent random IO performance the contiguous IO performance often isn’t much better than hard drives. My Intel SSDSC2CT12 300i 128G can do over 5000 random seeks per second but for sustained contiguous filesystem IO can only do 225M/s for writes and 274M/s for reads. The contiguous IO performance is less than twice as good as a cheap 3TB SATA disk. It also seems that the performance of SSDs aren’t as consistent as that of hard drives, when a hard drive delivers a certain level of performance then it can generally do so 24*7 but a SSD will sometimes reduce performance to move blocks around (the erase block size is usually a lot larger than the filesystem block size).

It’s obvious that SSDs allow significantly better swap performance and therefore make it viable to run a system with more swap in use but that doesn’t allow unlimited swap. Even when using programs like Chromium (which seems to allocate huge amounts of RAM that aren’t used much) it doesn’t seem viable to have swap be much bigger than 4G on a system with 4G of RAM. Now I could buy another SSD and use two swap spaces for double the overall throughput (which would still be cheaper than buying a PC that supports 8G of RAM), but that still wouldn’t solve all problems.

One issue I have been having on occasion is BTRFS failing to allocate kernel memory when managing snapshots. I’m not sure if this would be solved by adding more RAM as it could be an issue of RAM fragmentation – I won’t file a bug report about this until some of the other BTRFS bugs are fixed. Another problem I have had is when running Minecraft the driver for my ATI video card fails to allocate contiguous kernel memory, this is one that almost certainly wouldn’t be solved by just adding more swap – but might be solved if I tweaked the kernel to be more aggressive about swapping out data.

In 2007 when using hard drives for swap I found that the maximum space that could be used with reasonable performance for typical desktop operations was something less than 2G. Now with a SSD the limit for usable swap seems to be something like 4G on a system with 4G of RAM. On a system with only 2G of RAM that might allow the system to be usable with swap being twice as large as RAM, but with the amounts of RAM in modern PCs it seems that even SSD doesn’t allow using a swap space larger than RAM for typical use unless it’s being used for hibernation.

Conclusion

It seems that nothing has significantly changed in the last 7 years. We have more RAM, faster storage, and applications that are more memory hungry. The end result is that swap still isn’t very usable for anything other than hibernation if it’s larger than RAM.

It would be nice if application developers could stop increasing the use of RAM. Currently it seems that the RAM requirements for Linux desktop use are about 3 years behind the RAM requirements for Windows. This is convenient as a PC is fully depreciated according to the tax office after 3 years. This makes it easy to get 3 year old PCs cheaply (or sometimes for free as rubbish) which work really well for Linux. But it would be nice if we could be 4 or 5 years behind Windows in terms of hardware requirements to reduce the hardware requirements for Linux users even further.

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Syndicated 2014-04-19 04:58:15 from etbe - Russell Coker

Phone Based Lectures

Early this month at a LUV meeting I gave a talk with only my mobile phone to store notes. I used Google Keep to write the notes as it’s one of the easiest ways of writing a note on a PC and quickly transferring it to a phone – if I keep doing this I will find some suitable free software for this task. Owncloud seems promising [1], but at the moment I’m more concerned with people issues than software.

Over the years I’ve experimented with different ways of presenting lectures. I’m now working with the theory that presenting the same data twice (by speaking and text on a projector) distracts the audience and decreases learning.

Editing and Viewing Notes

Google Keep is adequate for maintaining notes, it’s based on notes that are a list of items (like a shopping list) which is fine for lecture notes. It probably has lots of other functionality but I don’t care much about that. Keep is really fast at updating notes, I can commit a change on my laptop and have it visible on my phone in a few seconds over 3G.

Most of the lectures that I’ve given have involved notes on a laptop. My first laptop was a Thinkpad 385XD with a 12.1″ display and all my subsequent laptops have had a bigger screen. When a laptop with a 12″ or larger screen is on a lectern I can see the notes at a glance without having to lean forward when 15 or fewer lines of text are displayed on the screen. 15 lines of text is about the maximum that can be displayed on a slide for the audience to read and with the width of a computer display or projector is enough for a reasonable quantity of text.

When I run Keep on my Galaxy Note 2 it displays about 20 rather short lines of text in a “portrait” orientation (5 points for a lecture) and 11 slightly longer lines in a “landscape” orientation (4 points). In both cases the amount of text displayed on a screen is less than that with a laptop while the font is a lot smaller. My aim is to use free software for everything, so when I replace Keep with Owncloud (or something similar) I will probably have some options for changing the font size. But that means having less than 5 points displayed on screen at a time and thus a change in the way I present my talks (I generally change the order of points based on how well the audience seem to get the concepts so seeing multiple points on screen at the same time is a benefit).

The Samsung Galaxy Note 2 has a 5.5″ display which is one of the largest displays available in a phone. The Sony Xperia X Ultra is one of the few larger phones with a 6.44″ display – that’s a large phone but still not nearly large enough to have more than a few points on screen with a font readable by someone with average vision while it rests on a lectern.

The most obvious solution to the problem of text size is to use a tablet. Modern 10″ tablets have resolutions ranging from 1920*1080 to 2560*1600 and should be more readable than the Thinkpad I used in 1998 which had a 12″ 800*600 display. Another possibility that I’m considering is using an old phone, a Samsung Galaxy S weighs 118 to 155 grams and is easier to hold up than a Galaxy Note 2 which weighs 180g. While 60g doesn’t seem like much difference if I’m going to hold a phone in front of me for most of an hour the smaller and lighter phone will be easier and maybe less distracting for the audience.

Distributing URLs

When I give a talk I often want to share the addresses of relevant web sites with the audience. When I give a talk with the traditional style lecture notes I just put the URLs on the final page (sometimes using tinyurl.com) for people to copy during question time. When I use a phone I have to find another way.

I did a test with QR code recognition and found that a code that takes up most of the width of the screen of my Galaxy Note 2 can be recognised by a Galaxy S at a distance of 50cm. If I ran the same software on a 10″ tablet then it would probably be readable at a distance of a meter, if I had the QR code take up the entire screen on a tablet it might be readable at 1.5m away, so it doesn’t seem plausible to hold up a tablet and allow even the first few rows of the audience to decode a QR code. Even if newer phones have better photographic capabilities than the Galaxy S that I had available for testing there are still lots of people using old phones who I want to support. I think that if QR codes are to be used they have to be usable by at least the first three rows of the audience for a small audience of maybe 50 people as that would allow everyone who’s interested to quickly get in range and scan the code at the end.

Chris Samuel has a photo (taken at the same meeting) showing how a QR code from a phone could be distributed to a room [2]. But that won’t work for all rooms.

One option is to just have the QR code on my phone and allow audience members to scan it after the lecture. As most members of the audience won’t want the URLs it should be possible for the interested people to queue up to scan the QR code(s).

Another possibility I’m considering is to use a temporary post on my documents blog (which isn’t syndicated) for URLs. The WordPress client for Android works reasonably well so I could edit the URL list at any time. That would work reasonably well for talks that have lots of URLs – which is quite rare for me.

A final option is to use Twitter, at the end of a talk I could just tweet the URLs with suitable descriptions. A good portion of the Tweets that I have written is URLs for web sites that I find interesting so this isn’t a change. This is probably the easiest option, but with the usual caveat of using a proprietary service as an interim measure until I get a free software alternative working.

Any suggestions?

Please comment if you have any ideas about ways of addressing these issues.

Also please let me know if anyone is working on a distributed Twitter replacement. Please note that anything which doesn’t support followers on multiple servers and re-tweets and tweeting to users on other servers isn’t useful in this regard.

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Syndicated 2014-04-19 03:49:21 from etbe - Russell Coker

Replacement Credit Cards and Bank Failings

I just read an interesting article by Brian Krebs about the difficulty in replacing credit cards [1].

The main reason that credit cards need to be replaced is that they have a single set of numbers that is used for all transactions. If credit cards were designed properly for modern use (IE since 2000 or so) they would act as a smart-card as the recommended way of payment in store. Currently I have a Mastercard and an Amex card, the Mastercard (issued about a year ago) has no smart-card feature and as Amex is rejected by most stores I’ve never had a chance to use the smart-card part of a credit card. If all American credit cards had a smart card feature which was recommended by store staff then the problems that Brian documents would never have happened, the attacks on Target and other companies would have got very few card numbers and the companies that make cards wouldn’t have a backlog of orders.

If a bank was to buy USB smart-card readers for all their customers then they would be very cheap (the hardware is simple and therefore the unit price would be low if purchasing a few million). As banks are greedy they could make customers pay for the readers and even make a profit on them. Then for online banking at home the user could use a code that’s generated for the transaction in question and thus avoid most forms of online banking fraud – the only possible form of fraud would be to make a $10 payment to a legitimate company become a $1000 payment to a fraudster but that’s a lot more work and a lot less money than other forms of credit card fraud.

A significant portion of all credit card transactions performed over the phone are made from the customer’s home. Of the ones that aren’t made from home a significant portion would be done from a hotel, office, or other place where a smart-card reader might be conveniently used to generate a one-time code for the transaction.

The main remaining problem seems to be the use of raised numbers. Many years ago it used to be common for credit card purchases to involve using some form of “carbon paper” and the raised numbers made an impression on the credit card transfer form. I don’t recall ever using a credit card in that way, I’ve only had credit cards for about 18 years and my memories of the raised numbers on credit cards being used to make an impression on paper only involve watching my parents pay when I was young. It seems likely that someone who likes paying by credit card and does so at small companies might have some recent experience of “carbon paper” payment, but anyone who prefers EFTPOS and cash probably wouldn’t.

If the credit card number (used for phone and Internet transactions in situations where a smart card reader isn’t available) wasn’t raised then it could be changed by posting a sticker with a new number that the customer could apply to their card. The customer wouldn’t even need to wait for the post before their card could be used again as the smart card part would never be invalid. The magnetic stripe on the card could be changed at any bank and there’s no reason why an ATM couldn’t identify a card by it’s smart-card and then write a new magnetic stripe automatically.

These problems aren’t difficult to solve. The amounts of effort and money involved in solving them are tiny compared to the costs of cleaning up the mess from a major breach such as the recent Target one, the main thing that needs to be done to implement my ideas is widespread support of smart-card readers and that seems to have been done already. It seems to me that the main problem is the incompetence of financial institutions. I think the fact that there’s no serious competitor to Paypal is one of the many obvious proofs of the incompetence of financial companies.

The effective operation of banks is essential to the economy and the savings of individuals are guaranteed by the government (so when a bank fails a lot of tax money will be used). It seems to me that we need to have national banks run by governments with the aim of financial security. Even if banks were good at their business (and they obviously aren’t) I don’t think that they can be trusted with it, an organisation that’s “too big to fail” is too big to lack accountability to the citizens.

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Syndicated 2014-04-12 00:25:39 from etbe - Russell Coker

Finding Corrupt Files that cause a Kernel Error

There is a BTRFS bug in kernel 3.13 which is triggered by Kmail and causes Kmail index files to become seriously corrupt. Another bug in BTRFS causes a kernel GPF when an application tries to read such a file, that results in a SEGV being sent to the application. After that the kernel ceases to operate correctly for any files on that filesystem and no command other than “reboot -nf” (hard reset without flushing write-back caches) can be relied on to work correctly. The second bug should be fixed in Linux 3.14, I’m not sure about the first one.

In the mean time I have several systems running Kmail on BTRFS which have this problem.

(strace tar cf – . |cat > /dev/null) 2>&1|tail

To discover which file is corrupt I run the above command after a reboot. Below is a sample of the typical output of that command which shows that the file named “.trash.index” is corrupt. After discovering the file name I run “reboot -nf” and then delete the file (the file can be deleted on a clean system but not after a kernel GPF). Of recent times I’ve been doing this about once every 5 days, so on average each Kmail/BTRFS system has been getting disk corruption every two weeks. Fortunately every time the corruption has been on an index file so I don’t need to restore from backups.

newfstatat(4, ".trash.index", {st_mode=S_IFREG|0600, st_size=33, …}, AT_SYMLINK_NOFOLLOW) = 0
openat(4, ".trash.index", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC) = 5
fstat(5, {st_mode=S_IFREG|0600, st_size=33, …}) = 0
read(5,  <unfinished …>
+++ killed by SIGSEGV +++

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Syndicated 2014-04-06 11:55:48 from etbe - Russell Coker

Comparing Telcos Again

Late last year I compared the prices of mobile providers after Aldi started getting greedy [1]. Now Aldi have dramatically changed their offerings [2] so at least some of the phones I manage have to be switched to another provider.

There are three types of use that are of interest to me. One is for significant use, that means hours of calls per month, lots of SMS, and at least 2G of data transfer. Another is for very light use, maybe a few minutes of calls per month where the aim is to have the lowest annual price for an almost unused phone. The third is somewhere in between – and being able to easily switch between plans for moderate and significant use is a major benefit.

Firstly please note that I have no plans to try and compare all telcos, I’ll only compare ones that seem to have good offers. Ones with excessive penalty clauses or other potential traps are excluded.

Sensible Plans

The following table has the minimum costs for plans where the amount paid counts as credit for calls and data, this makes it easy to compare those plans.

Plan Cost per min or SMS Data Minimum cost
AmaySIM As You Go [3] $0.12 $0.05/meg, $19.90 for 2.5G in 30 days, $99.90 for 10G in 365days $10 per 90 days
AmaySIM Flexi [4] $0.09 500M included, free calls to other AmaySIM users, $19.90 for 2.5G in 30 days, $99.90 for 10G in 365days $19.90 per 30 days
Aldi pre-paid [5] $0.12 $0.05/meg, $30 for 3G in 30 days $15 per 365 days

Amaysim has a $39.90 “Unlimited” plan which doesn’t have any specific limits on the number of calls and SMS (unlike Aldi “Unlimited”) [6], that plan also offers 4G of data per month. The only down-side is that changing between plans is difficult enough to discourage people from doing so, but if you use your phone a lot every month then this would be OK. AmaySIM uses the Optus network.

Lebara has a $29.90 “National Unlimited” plan that offers unlimited calls and SMS and 2G of data [7]. The Lebara web site doesn’t seem to include details such as how long pre-paid credit lasts, the lack of such detail doesn’t give me confidence in their service. Lebara uses the Vodafone network which used to have significant problems, hopefully they fixed it. My lack of confidence in the Vodafone network and in Lebara’s operations makes me inclined to avoid them.

Obscure Plans

Telechoice has a $28 per month “i28″ plan that offers unlimited SMS, $650 of calls (which can be international) at a rate of over $1 per minute, unlimited SMS, unlimited calls to other Telechoice customers, and 2G of data [8]. According to the Whirlpool forum they use the Telstra network although the TeleChoice web site doesn’t state this (one of many failings of a horrible site).

The TeleChoice Global Liberty Starter plan costs $20 per month and includes unlimited calls to other TeleChoice customers, unlimited SMS, $500 of calls at a rate of over $1 per minute, and 1G of data [9].

Which One to Choose

For my relatives who only rarely use their phones the best options are the AmaySIM “As You Go” [3] plan which costs $40 per 360 days and the Aldi prepaid which costs $15 per year. Those relatives are already on Aldi and it seems that the best option for them is to keep using it.

My wife typically uses slightly less than 1G of data per month and makes about 25 minutes of calls and SMS. For her use the best option is the AmaySIM “As You Go” [3] plan which will cost her about $4 in calls per month and $99.90 for 10G of data which will last 10 months. That will average out to about $13 per month. It could end up being a bit less because the 10G of data that can be used in a year gives an incentive to reduce data use while previously with Aldi she had no reason to use less than 2G of data per month. Her average cost will be $11.30 per month if she can make 10G of data last a year. The TeleChoice “Global Liberty Starter” [9] plan is also appealing, but it is a little more expensive at $20 per month, it would be good value for someone who averages more than 83 minutes per month and also uses almost 1G of data.

Some of my relatives use significantly less than 1G of data per month. For someone who uses less than 166MB of billable data per month then the Aldi pre-paid rate of $0.05 per meg [5] is the best, but with a modern phone that does so many things in the background and a plan that rounds up data use it seems almost impossible to be billed for less than 300MB/month. Even when you tell the phone not to use any mobile data some phones still do, on a Nexus 4 and a Nexus 5 I’ve found that the only way to prevent being billed for 3G data transfer is to delete the APN from the phone’s configuration. So it seems that the AmaySIM “As You Go” [3] plan with a 10G annual data pack is the best option.

One of my relatives needs less than 1G of data per month and not many calls, but needs to be on the Telstra network because their holiday home is out of range of Optus. For them the TeleChoice Global Liberty Starter [9] plan seems best.

I have been averaging a bit less than 2G of data transfer per month. If I use the AmaySIM “As You Go” [3] plan with the 10G data packs then I would probably average about $18 worth of data per month. If I could keep my average number of phone calls below $10 (83 minutes) then that would be the cheapest option. However I sometimes spend longer than that on the phone (one client with a difficult problem can involve an hour on the phone). So the TeleChoice i28 plan looks like the best option for me, it gives $650 of calls at a rate of $0.97 per minute + $0.40 connection (that’s $58.60 for a hour long call – I can do 11 of those calls in a month) and 2G of data. The Telstra coverage is an advantage for TeleChoice, I can run my phone as a Wifi access point so my wife can use the Internet when we are out of Optus range.

Please let me know if there are any good Australian telcos you think I’ve missed or if there are any problems with the above telcos that I’m not aware of.

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Syndicated 2014-04-01 11:44:26 from etbe - Russell Coker

Links March 2014

Typing Animal wrote an interesting article about the dangers of stainless steel in a medical environment [1]. Apparently silver and copper are best due to the oligodynamic effect. Instead of stainless steel drinking bottles they should sell silver plated drinking bottles for kids, I’m sure that lots of parents would pay extra for that.

Mark Kendall gave an interesting TED talk about a replacement for the hypodermic syringe in vaccinations [2]. His invention can reduce the cost of immunisation while increasing the effectiveness and avoiding problems with people who have a needle phobia.

The TED blog has an interesting interview with Will Potter about the use of the “war on terror” to silence journalists and the invention of the term “eco terrorism” for non-violent people who are politically active [3].

The TED blog has an interesting article by Kate Torgovnick May about designing products for sustainability [4]. It links to an insightful TED talk by Leyla Acaroglu about some of the complex issues related to sustainability [5].

Manoush Zomorodi wrote an informative article about How one college went from 10% female computer-science majors to 40% [6].

Slate has an interesting article by Jamelle Bouie showing the way that support for capital punishment in the US is linked to racism [7].

The Southern California Public Radio blog has an interesting article by Josie Huang about Suey Park and her success in using twitter to oppose racism [8].

Andrew Solomon wrote an insightful interview with the father of Adam Lanza for the New Yorker [9].

Waleed Aly wrote an insightful article about George Brandis’ attempt to change the Racial Discrimination Act specifically to allow Andrew Bolt to be racist [10]. He describes it as “the whitest piece of proposed legislation I’ve encountered” which is significant in a country with as much racism as Australia. Really we need stronger laws against racism, there should be no right to be bigoted.

A German Court has ruled that “non commercial” licenses don’t permit non-commercial organisations to re-publish material [11]. This seems bogus to me, I’d be happy to have my non-commercial licensed work published by a non-commercial publishing organisation – just as long as they don’t run adverts on the page.

Professors Woolley and Malone wrote an interesting article about their research into group performance, apparently having more women in a group improves the collective intelligence of a group, but having smarter men in the group doesn’t [12].

Susie Hill wrote an article about the SPARX computer game that is designed to treat adolescent depression [13]. They are working on a “rainbow” edition for GLBT kids and a version for Maoris. Unfortunately their web site is down right now and the version at archive.org says that it’s currently only available to participants in a clinical trial.

Tim Chevalier wrote an insightful article explaining why people who campaign against equality shouldn’t be given senior positions in corporations [14].

Zeynep Tufekci wrote an insightful article about how French High Theory and Dr. Seuss can help explain gender problems in geek communities [15].

Hannah Levintova wrote an informative article for Mother Jones about how the US based hate group the World Congress of Families incites homophobic violence in Russia [16].

Josh Sanburn wrote an article for Time about people in the Deep South who claim to be Christian giving away guns to encourage people to attend church [17]. This is the same part of the world where people who claimed to be Christian used their “religion” as an excuse for supporting slavery. I’m quitting bourbon, too much evil comes from that part of the world and I’m not buying anything that comes from there.

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Syndicated 2014-03-31 10:55:42 from etbe - Russell Coker

The Aspie Accent

I am often asked about my “accent”. The most common guess is that it’s a “British” accent, while I lived in London for about a year I don’t think that my accent changed much during that time (people have commented on the way I speak since I was in primary school). Also there isn’t a “British accent” anyway, the Wikipedia page of Regional Accents of English has the first three sections devoted to accents in the island of Britain (and Northern Ireland is part of the United Kingdom which people often mean when they sat “Britain”). The Received Pronounciation is the main BBC accent and the accent that is most associated with Britain/England/the UK (which are three different things even though most people don’t know it) and I don’t think that I sound like that at all.

I’ve had various other guesses, the Netherlands (where I lived for a few years but mostly spoke to other foreigners), New Zealand (which I’ve visited a couple of times for conferences), Denmark (the closest I got was attending a conference in Sweden), and probably others I can’t remember.

If I actually had developed an accent from another country then it would probably be from the US. The amount of time I’ve spent watching Hollywood movies and watching US TV shows greatly exceeds the amount of time I’ve spent listening to people from all other countries. The fact that among all the people who wanted to try and guess where my accent supposedly originated none have ever included the US seems like strong evidence to suggest that I don’t have any sort of accent that really derives from another country. Also I have never had someone mistake me for being a resident of their own country based on accent which seems like clear evidence that all claims about me having a foreign accent are bogus.

Autism forums such as WrongPlanet.net [1] always turn up plenty of results for a search on “accent”. In such discussions it seems that a “British accent” is most common mistake and there are often theories raised about why that is – often related to speaking in a formal or precise way or by using a large vocabulary. Also in such discussions the list of countries that people supposedly have accents from is very inclusive, it seems that any country that the listener has heard of but doesn’t know that well is a good candidate. The fact that Aspies from outside the US are rarely regarded as having an American accent could be due to the fact that Hollywood has made most of the world population aware of what most American accents sound like.

Also if I really had some sort of accent from another country then probably someone would comment on that when I’m outside Australia. When I’m travelling people tend to recognise my accent as Australian, while it doesn’t please me when someone thinks that I sound like Crocodile Dundee (as happened in the Netherlands) it might not be entirely inaccurate.

This is Annoying

The way the issue of accent is raised is generally in the form of people asking where I’m from, it seems to imply that they don’t think I belong in Australia because of the way I speak. It’s particularly annoying when people seem unable to realise that they are being obnoxious after the first wrong guess. When I reply “no” to the first “are you from $COUNTRY” question and don’t offer any further commentary it’s not an invitation to play 20 questions regarding where I’m supposedly from, it’s actually an indication that I’m not interested in a conversation on that topic. A Social Skills 101 course would include teaching people that when someone uses one-word answers to your questions it usually means that they either don’t like your questions or don’t want to talk to you.

Social Skills vs Status

The combination of persistence and misreading a social situation which are involved when someone interrogates me about my supposed accent are both parts of the diagnostic criteria for Autism. But I generally don’t get questions about my “accent” in situations where there are many Aspies (IE anything related to the Free Software community). I think that this is because my interactions with people in the Free Software community are based around work (with HR rules against being a jerk) and community events where no-one would doubt that I belong.

I mostly get questions about my “accent” from random middle-class white people who feel entitled to query other people about their status who I meet in situations where there is nothing restraining them from being a jerk. For example random people I meet on public transport.

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Syndicated 2014-03-26 23:44:35 from etbe - Russell Coker

Nexus5 Armourdillo Hybrid Case

back of case showing both layers front of case case stand showing the mirror surface of the Nexus 5

I’ve just been given an Armourdillo Hybrid case for the Nexus 5 [1] to review. The above pictures show the back of the case, the front of the case, the stand, and the front of the case with the screen blank. When I first photographed the case the camera focused on a reflection of the window, I include that picture for amusement and to demonstrate how reflective the phone screen is.

This case is very hard, the green plastic is the soft inner layer which is still harder than the plastic in a typical “gel case”. The black part is polycarbonate which is very hard and also a little slippery. The case is designed with lots of bumps for grip (a little like the sole of a running shoe) so it’s not likely to slip out of your hand. But the polycarbonate slides easily on plastic surfaces such as the dash of a car. It’s fortunate that modern cars have lots of “cup holders” that can be used for holding a phone.

I haven’t dropped the phone since getting the new case, but I expect that the combination of a hard outer shell and a slightly softer inner shell (to cushion the impact) will protect it well. All the edges of the case extend above the screen so dropping the phone face down on a hard flat surface shouldn’t cause any damage.

The black part has a stand for propping the phone on it’s side to watch a movie. The stand is very solid and is in the ideal position for use on soft surfaces such as a doona or pillow for watching TV in bed.

Appearance

This case is mostly designed to protect the phone and the bumps that are used for grip detract from the appearance IMHO. I think that the Ringke Fusion case for my Nexus 4 [2] looks much better, it’s a trade-off between appearance and functionality.

My main criteria for this case were good protection (better than a gel case) and small size (not one of the heavy waterproof cases). It was a bonus to get a green case for the Enlightened team in Ingress. NB Armourdillo also offers a blue case for the Resistance team in Ingress as well as other colors.

MobileZap also have a number of other cases for the Nexus 5 [3].

Related posts:

  1. Nexus 4 Ringke Fusion Case I’ve been using Android phones for 2.5 years and...
  2. Samsung Galaxy S3 First Review with Power Case My new Samsung Galaxy S3 arrived a couple of days...
  3. Nexus 4 My wife has had a LG Nexus 4 for about...

Syndicated 2014-03-25 05:42:25 from etbe - Russell Coker

Aldi Deserves an Award for Misleading Email

Aldi Mobile has made a significant change to their offerings. They previously had an offer of $35 for “unlimited” calls and 2.5G of data in a month for which they had to publicly apologise for misleading customers as 2500 minutes of calls a month (83 minutes per day) is no-where near unlimited [1]. They also had an offer of $15 for 2G of data.

In an email about this Aldi said “Many of our customers are using a lot less than what is included in our current $35 plan. So we will soon be introducing new Value Packs with more flexible options; meaning you only pay for what you really need and they start from just $10.“. That is grossly misleading, if they offered new plans in addition to the old ones and allowed customers to choose the plan that is the best match then it would be useful to some customers. But removing the supposedly “unlimited” plan and the $15 for 2G of data option is removing affordable options for people who want to use their phones for lots of calls or very few calls but moderate amounts of data use.

New Plans

The base rate for calls on Aldi pre-paid is $0.12 per minute and $0.12 per SMS, consider every mention of “minute” in this section to be “minute or SMS”. The Aldi Newplans page [2] starts with a $10 per month plan which offers 100 minutes of calls which would be $12 at the previous rate of $0.12 per minute. That is OK value when compared to just using the pre-paid calls if you consistently use more than 83 minutes of calls per month. However if you don’t use 84 minutes of calls (EG you don’t speak much on the phone and use Google Hangouts instead of SMS) then it’s not good value. Also the advertised data use is $5 per 100MB, which is way below what is needed for a typical user with an Android phone. My mother in law was barely able to stick within a limit of 300MB/month when that was her limit, but while using the Aldo 2G/month bolt-on she’s increased her data usage.

The smallest of the new plans costs $20 per month, it provides 300 minutes of calls and includes 300MB of data. For an extra $7 you can get another 300MB of data. For my mother in law it seems that the cheapest option on the new plans would be $27 per month, that would cover the 60 minutes of calls she might make and the 450MB of data she’s probably using. That’s significantly more expensive than her previous cost of $15 for 2G of data and $7.20 for calls and has the additional difficulty that I would have to be more involved in helping her avoid excessive data use.

The 2G data bolt-on was really good for some of my relatives, when they use that and configure their phones not to update software over 3G they never had to ask me about any problems related to excess data use. So my mother in law is facing an extra $5 per month (or maybe more depending on data use) and more time spent calling me for tech support.

The data bolt on that Aldi is going to offer in future is $30 for 3G of data to replace the previous offer of $15 for 2G of data. The cost will be unchanged for anyone who uses between 2G and 3G a month, for everyone who uses less than 2G or more than 3G the data bolt-on will cost more. There is simply no possibility for any Aldi data-only customer to save on data use. The only way someone who uses a moderate amount of data could save money is if they use more than 160 minutes of calls and less than 1G of data.

Disclaimer

My analysis above is based on interpreting the Aldi web site. As with most telcos they aren’t trying to make things easy in this regard, it seems that the consensus of opinion among telcos is to use complex pricing to make it difficult to compare and reduce competitive pressure. I blame any inaccuracies in my analysis on the Aldi web site.

Why Aldi Shouldn’t Mislead Customers

Aldi isn’t primarily a mobile phone company, their main business is running a supermarket. The trust of customers is important to them, raising prices when competition goes away is one thing, but misleading customers about it is another. If Aldi were to honestly say “now that Kogan Mobile no longer exists there is nothing forcing us to have low prices” then I’d have a lot more respect for their company and be more inclined to shop at their supermarket.

It’s a sad indictment of our society that I need to include a “why lying is wrong” section in such a blog post.

Related posts:

  1. Aldi Changes, Cheap Telcos, and Estimating Costs I’ve been using Aldi as my mobile phone provider for...
  2. The End of Kogan Mobile Kogan Mobile has just announced that Telstra succeeded in it’s...
  3. Returning the Aldi Tablet I have decided to return the 7″ Android tablet I...

Syndicated 2014-03-23 07:38:13 from etbe - Russell Coker

BTRFS Status March 2014

I’m currently using BTRFS on most systems that I can access easily. It’s not nearly reliable enough that I want to install it on a server in another country or an embedded device that’s only accessible via 3G, but for systems where I can access the console it’s not doing too badly.

Balancing and Space Allocation

# btrfs filesystem df /
Data, single: total=103.97GiB, used=85.91GiB
System, DUP: total=32.00MiB, used=20.00KiB
Metadata, DUP: total=1.78GiB, used=1.31GiB
# df -h /

Filesystem Size Used Avail Use% Mounted on
/dev/disk/by-uuid/ac696117-473c-4945-a71e-917e09c6503c 108G 89G 19G 84% /

Currently there are still situations where it can run out of space and deadlock on freeing space. The above shows the output of the btrfs df command and the regular df command, I have about 106G of disk space used by data and metadata in BTRFS while df shows that the entire filesystem (IE the block device) is 108G. So if I use another 2G of data or metadata then the system is at risk of deadlocking. To avoid that happening I have to run “btrfs balance start /” to start a balance which defragments the space use and frees some blocks. Currently there is a bug in BTRFS (present in all Debian/Unstable kernels) which prevents a balance operation from completing when systemd is used in a default configuration (there’s something about the way systemd accesses it’s journal files that triggers a BTRFS bug). This is really inconvenient, particularly given that there’s probably a strong correlation between people who use experimental filesystems and people who use experimental init programs.

When you get to the stage of the filesystem being deadlocked you can sometimes recover by removing snapshots and sometimes by adding a new device to the filesystem (even a USB flash drive will do). But I once had a filesystem get into a state where there wasn’t enough space to balance, add a device, or remove a snapshot – so I had to do a backup/format/restore.

Quota Groups

Last time I asked the developers (a few weeks ago) they told me that quota groups aren’t ready to use. They also said that they know about enough bugs that there’s no benefit in testing that feature. Even people who want to report bugs in BTRFS shouldn’t use quotas.

Kernel Panics with Kmail

I’ve had three systems develop filesystem corruption on files related to Kmail (the email program from KDE). I suspect that Kmail is triggering a bug in BTRFS. On all three systems the filesystem developed corruption that persisted across a reboot. One of the three systems was fixed by deleting the file for the Outbox, the others are waiting for kernel 3.14 which is supposed to fix the bug that causes kernel panics when accessing the corrupted files in question.

I don’t know whether kernel 3.14 will fix the bug that caused the corruption in the first place.

Conclusion

As I don’t use quotas BTRFS is working well for me on systems that have plenty of storage space and don’t run Kmail. There are some systems running systemd where I plan to upgrade the kernel before all the filesystem space is allocated. One of my systems is currently running SysVinit so I can balance the filesystem.

Apart from these issues BTRFS is working reasonably well for me. I haven’t yet had it’s filesystem checksums correct corrupted data from disk in any situation other than tests (I have had ZFS correct such an error, so hardware I use does benefit from this). I have restored data from BTRFS snapshots on many occasions, so that feature has been a major benefit for me. When I had a system with faulty RAM the internal checks in BTRFS alerted me to the problem and I didn’t lose any data, the filesystem became read-only and I was able to copy everything off even though it was too corrupted for writes.

Related posts:

  1. Starting with BTRFS Based on my investigation of RAID reliability [1] I have...
  2. Using BTRFS I’ve just installed BTRFS on some systems that matter to...
  3. ZFS vs BTRFS on Cheap Dell Servers I previously wrote about my first experiences with BTRFS [1]....

Syndicated 2014-03-16 03:42:09 from etbe - Russell Coker

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