H. Mijail's Blog

Living in Warsaw, I got tired of worrying about the air quality – which some days during winter got reported as worse than that of infamously polluted Beijing. So some months ago I bought an air purifier. I had a number of doubts about how to use it so it was effective: does it have to work all day? The purifier's power level depends on the room's size, how do I know that it's working as it should? Air quality sensors included in these purifiers are said to be pretty unreliable, are they any useful at all? How does air quality indoors correlate to air quality reported by an official station about 1 km away from home – which daily recommended wearing a mask during winter!? What happens if I just leave the windows closed, or if I open them for a while? ... So I bit the bullet and bought an air quality sensor, which cost almost as much as the purifier itself. And these are my results and tips for anyone thinking about doing the same.

A quick experiment to see what is faster to encrypt a TimeMachine network volume: using Synology's folder encryption or OS X's automatic TM encryption. Copying a directory with 1200 files and directories in it (source files and compilation products), about 125 MB in total: Unencrypted: 86 sec Synology's encryption: 90 sec OS X's encryption: 10 sec So, not much to discuss about it: OS X's encryption wins. Notes: This was done by the verily scientific method of trying a couple of times and counting seconds aloud. At the beginning I was thinking about doing it in some scripted, repeatable, strict way to control for things like caching and blah blah. But, a 1:9 difference? That's convincing enough for me, kthxbai. I simulated OS X's TM encryption by creating an encrypted disk image (AES 256 bit, sparsebundle) in an unencrypted folder in the Synology's server. This might not be the same than the real TM encryption, since that seems to be done by F...

I found a strange situation when programming in C for AVRs. I have a bunch of structures to be worked on, but any of them can be flagged "active" or not at any given moment, to signal whether they need further work. My first approximation was to add a (uint8_t volatile: set in main, checked in interrupt time) member variable named "active" to the struct, to quickly check/set each structure. Shock: only looping through the array checking the "active" member variables was taking an enormous amount of time – about 20 clock cycles per access !

( see the 2014 update ) About one year ago I was tired of the problems with my then-current internet provider, Play. So I decided to try the 4 major operators in Poland. I got a "starter pack" for each one, which can be bought for about 10 zl each, and tried them with my telephones/modems/computers. These are the results of testing with speedtest.net, pingtest.net, youtube's speed test and torrenting some big Linux disc image. And since this is mobile internet, I tried each in a set of places in Warsaw - and some even outside of the city. Note that I was looking for smartphone use: voice + data, with data being in the 5 GB/month range, possibly more. So data packages measured in MB didn't cut it (since they are usually much more expensive). And internet-only SIMs were out, too. The tests are one year old, but I can confirm that the results are still valid at least for T-Mobile and Play, since I still use them both. For non-technically inclined people, the summ...

After a couple of too-close-together performance-competition-between-browsers thingies, I decided to make my very own quick & dirty benchmark of current browsers. Webkit-based at least, although soon I'd like to at least try again Firefox; it's been months since I abandoned it for Webkit itself, due to a multitude of small problems, some of them caused by myself (much more than a hundred tabs always open, lots of extensions to lessen the load) but magnified by Firefox itself (extensions failing, slowness even when with much more reasonable numbers of tabs, sluggish Flash performance, problematic Java)... In fact it's a great moment to make this kind of test, since Safari 4.0.2 has just appeared, Stainless 0.6.5 too, and ... well, WebKit has a recent nightly (r45641). Chrome is the available one right now: 3.0.192 (developer release) A surprise has been to learn that Opera seems to have abandoned the race some time ago (ten times slower, javascript-wise, than any of th...