The following program, compiled with clang 1.1, runs 500 times faster than the gcc4.5-compiled code (in both cases with -O2): <span style="color:#008200;">#include <stdio.h></span> <span style="color:#008200;">#define len 1000000000L</span> <span style="color:#830000;">unsigned long</span> <span style="color:#010181;">f</span><span style="color:#000000;">(</span><span style="color:#830000;">unsigned long</span> a<span style="color:#000000;">,</span> <span style="color:#830000;">unsigned long</span> b<span style="color:#000000;">)</span> <span style="color:#010181;">__attribute__</span><span style="color:#000000;">((</span>noinline<span style="color:#000000;">));</span> <span style="color:#830000;">int</span> <span style="color:#010181;">main</span><span style="color:#000000;">()</span> <span style="color:#000000;">{</span> <span style="color:#010181;">printf</span><span style="color:#000000;">(</span><span style="color:#ff0000;">"%lu</span><span style="color:#ff00ff;">\n</span><span style="color:#ff0000;">"</span><span style="color:#000000;">,</span> <span style="color:#010181;">f</span><span style="color:#000000;">(</span><span style="color:#2928ff;">0</span><span style="color:#000000;">,</span> <span style="color:#2928ff;">2</span><span style="color:#000000;">*</span>len<span style="color:#000000;">));</span> <span style="color:#000000;font-weight:bold;">return</span> <span style="color:#2928ff;">0</span><span style="color:#000000;">;</span> <span style="color:#000000;">}</span> <span style="color:#830000;">unsigned long</span> <span style="color:#010181;">f</span><span style="color:#000000;">(</span><span style="color:#830000;">unsigned long</span> a<span style="color:#000000;">,</span> <span style="color:#830000;">unsigned long</span> b<span style="color:#000000;">)</span> <span style="color:#000000;">{</span> <span style="color:#830000;">unsigned long</span> sum <span style="color:#000000;">=</span> <span style="color:#2928ff;">0</span><span style="color:#000000;">;</span> <span style="color:#000000;font-weight:bold;">for</span> <span style="color:#000000;">(;</span> a <span style="color:#000000;"><</span> b<span style="color:#000000;">;</span> a<span style="color:#000000;">++)</span> sum <span style="color:#000000;">+=</span> a<span style="color:#000000;">;</span> <span style="color:#000000;font-weight:bold;">return</span> sum<span style="color:#000000;">;</span> <span style="color:#000000;">}</span> Now, I would be interested to see what’s happening here. I took a look at the assembler code both compilers create, but the only thing I found out so far is that gcc’s assembly is easier to understand - 50 lines (gcc) vs 134 lines (clang). If someone knows the answer, please tell me. ... Read more 》

Today, I got an email from an user of one of my Python scripts asking why the script t does not work on Arch Linux anymore. As it turns out, the Arch Linux team decided to switch /usr/bin/python to Python 3.0 and use python2 for Python 2.X versions. By doing this, they decided to make their distribution incompatible to almost any Python script in the world. Arch Linux’s decision to diverge from the rest of the world that uses python for Python 2.X and python3 for Python 3.X is stupid. And doing this without updating reverse dependencies beforehand and thus breaking packages in their own distribution is insane. In the end this means that if you use Arch Linux, you should consider switching to a distribution that does things the right way: Debian. You can also switch to Ubuntu, that’s normally just a bit less right (= faster). But using a distribution that does those crazy things in such an irresponsible way is really insane. ... Read more 》

In today’s Linux distributions, there are usually two to three levels of package management. In this blog post, I will explain the three levels of package management. 1. Local (dpkg, rpm) The first level of package management is the ’local’ level. This level consists of package management tools that install and/or remove packages via package archives such as .deb or .rpm files and a database of the local’s system state. ... Read more 》

It seems that Google is blocking wikileaks.org in its ‘Public DNS’ servers (8.8.8.8 and 8.8.4.4): <div id="_mcePaste">; <<>> DiG 9.7.1-P2 <<>> @8.8.8.8 wikileaks.org ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 50227 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;wikileaks.org. IN A ;; Query time: 2457 msec ;; SERVER: 8.8.8.8#53(8.8.8.8) ;; WHEN: Fri Aug 27 18:10:43 2010 ;; MSG SIZE rcvd: 31</div> Update: Sorry Google, for me doubting you. As it turns out, you did no evil, you were just a bit slower than the others.

APT2 is now called UPS (Universal Package System). The name is inspired by the company that delivers packages in those brown trucks and from the Image Packaging System (IPS) of OpenSolaris; and mvo writing ups after I proposed upt (über package tool) in IRC. It’s definitely better than my first thought which was ‘moo’ (and libmoo). Update: OK, let’s cancel this rename insanity.

As I wrote a few hours ago on deity@l.d.o (see http://lists.debian.org/deity/2010/08/msg00057.html), APT2 is back again. The first time, I tried Vala; but this time I wrote it in C (with the help of GLib, but no GObject) and the cache uses GVariant instead of an SQLite database. It’s really basic at the moment (no solver, package installation/removal), but it will improve. Read operation should be faster than with APT, although writes are slower (this will be fixed by reusing unchanged parts of the cache). ... Read more 》

MeeGo (Nokia/Intel): Openness does not seem to be very important for Nokia and Intel. They develop their stuff behind closed doors and then do a large code drop (once dropped, stuff gets developed in the open). In terms of professionality, it does not look much better: If you look at the meego-dev mailing list, you feel like you are in some kind of a kindergarten for open source developers - Things like HTML emails and top-posting appear to be completely normal for them, they don’t even follow the basic rules for emails and they also appear to ignore any advice on this topic. Oh, and writing a platform in GTK+ while pushing Qt as the supported toolset is not a good idea. ... Read more 》

In the past weeks, I was looking at several build systems. As it turned out, there is not a single sane generic build system out there. Autotools: Autotools are ugly, slow, and require an immense amount of code copies in the source tree. WAF: WAF is not as ugly as autools and it’s faster and does not generate Makefiles or stuff like this. But it has serious issues: It requires one to copy it to the source tarball, has no stable API, and requires Python for building. Furthermore, support for unit testing is broken: It runs the unit tests, but does not abort the build process if the tests fail and does not display why the tests fail. ... Read more 》

Wednesday, after some weeks with a flickering screen (or more precisely, something is causing GTK+ to redraw and the kernel to print ^@ in the terminal when you touch the screen, see http://jak-linux.org/tmp/20100628_002.mp4) in my 3 years old HP Compaq 6720s (which seems to be a software-hardware combination problem, at least it works in Ubuntu); I decided to buy a new laptop. It took me a few minutes to find the Lenovo ThinkPad Edge 15 NVL7VGE; which I ordered at notebooksbilliger.de at around 14:30 CEST using Express. On Thursday morning at 6:40 CEST, the device arrived. ... Read more 》

So, yesterday was my 0x14 (20th) birthday and Germany won the Eurovision Song Contest 2010. Next up is Formula One in Turkey and Sebastian Vettel starting from position 3, hopefully he manages to overtake Hamilton and Webber and win this race. Let’s see…