Within Temptation concert and photos

As previously announced I went to the Within Temptation concert in Zürich at the Volkshaus.
A venue I've never been before, but it was very comfortable, all seated places.
The music and the band were great, being part of their "The Unforgiving" tour, they played most songs from their latest album, and mixed in some old classics like "What Have You Done". Great show, congratulations!
Only negative was the long wait till they started playing, 1:20 after the official beginning of the concert, about 45 minutes of which were taken up by the opening act, can't remember their name, didn't like them much, and found them wholly inappropriate given what came after, it was some kind of (kinda-hard) rock, as opening for a gothic metal band? Oh well, I was probably just anxious for WT to start playing. :)
I took two videos:

  • Faster (Removed because of file size limitations)
  • What Have You Done (Removed because of file size limitations)

as well as some photos. The quality is terrible, I forgot my camera and had to do with the cell.
While I was uploading these, I noticed a few older StreetParade 2011 photos too.

And, this time from the real camera, I added the photos from the Computer-Linguistik week-end in Flumserberg.
That was incredibly fun, got to know lots of new people, it was a really great idea.

And while we're talking about great music, take a look at "Nickelback - When We Stand Together", amazing song, great video, profound message. Waiting on the new album!

Posted by Luca Longinotti on 05 Nov 2011 at 19:24
Categories: Longi, UZH Comments

CUPS EvenDuplex

Another remind-myself blog-post.
If you've got a printer like mine, which accepts PCL6, and expects there to always be an even number of pages when doing duplex printing, CUPS has a very easy solution for you. Open-source software usually always has.

*cupsEvenDuplex: True

Add that to your PPD file, and voilà, enjoy duplex working also when submitting three pages for printing!

Posted by Luca Longinotti on 01 Nov 2011 at 18:04
Categories: Hardware, Software Comments

Rig 2011/09/16

Second year at UZH looms on the horizon... Let's hope it's gonna be FUN! ;)

I haven't worked on Rig as much as I'd have liked this summer, but here's a quick summary of what did happen:

  • rig_str moved outside main source tree as its own module
  • further work went into testing
  • BS.txt's added, prototype configuration files for a new build-files generator, to maybe substitute CMake
  • improved support for Eclipse CDT 8.0 Static Analysis (awesome feature!)
  • fixed a bug in MurmurHash 3 (from upstream)
  • SMR using HPs was better name-spaced and the retire_mem function split up, to accommodate alternative SMR methods more easily
  • rig_mem_alloc_aligned() now supports additional flags; "RIG_MEM_ALLOC_ALIGN_PAD: pad allocation to next alignment boundary" was added (mostly for cache-line alignment to avoid false-sharing)
  • recursion was made optional for the MLock and the MRWLock, controlled by a flag. MRWLock now fully supports recursion, in both the read and write sides. This requires TLS-based owner checking to be performed, so it's not possible to disable that at compile-time for the MRWLock anymore. Non-recursive locks are the default now.

Next I'll be working on an implementation of Epoch-based SMR, which should offer better performance while traversing lists and ease of usage than HP-based SMR (as well as not having any patents I know of on it).

Posted by Luca Longinotti on 16 Sep 2011 at 14:37
Categories: Rig, C99 Comments

Software patents: WTF?

Disclaimer: I am not a lawyer, the following depicts my understanding of the issues at hand and my opinion. It is not legal counsel.
A discussion on StackOverflow I was having with the author of liblfds quickly went from technical to commercial/legal: software patents were mentioned, and the world became a little less clear...
Basically it boils down to the possibility that maybe, some algorithms/techniques/technologies implemented by Rig may be patented, and thus there might be legal questions about the usability of Rig in the US. I specify US here, because the EU doesn't recognize software patents to the extent of US patent law, where you can theoretically patent anything, which continuously results in totally bogus patents, like this one, if we're talking about data-structures and algorithms. As a Swiss citizen living in Switzerland I didn't even really ever think about this, since here software patents do not exists at all in the form possible in the US, anything purely algorithmic is hardly patentable.
As here we simply don't care about this possibility, if you want to code something, you do, also being part of the academic community, it's almost taken for granted that working on and off others research, improving, implementing etc. is possible and even encouraged, especially in an open-source fashion. So no, I wasn't trying to deceive anyone here, it just never entered my mind as a real concern that needs significant time dedicated to it. But I'm doing that now, so let's address Mr. Douglass' concerns:

A) the BSD license is incompatible with possible patents, meaning the license of code is related to possible patent claims

This is incorrect. License, copyright and patents are different things, even if somewhat related. It is perfectly possible to create code and license it, even if it knowingly violates granted patents, see the LAME case for an obvious example. Usually the license has nothing at all to do with possible patents that said code may be infringing, a code's license attributes the copyright and distribution as well as usage constraints upon the specific code in question. Patents are about ideas and techniques, especially the software ones, they usually just describe a procedure, which can be implemented in many a different way.
Conclusion: licenses relate to the particular code of the particular implementation, they just tell you what kind of restrictions I, as the author of the code, pose upon the code itself, with regards to distribution, use and re-use, linkage, etc.. There are licenses, like the GPL v3.0 and the Apache License, that do have extra bits and pieces that also regulate patent claims. The GPL v2.0, LGPL, BSD and most others don't give you any special rights regarding patents whatsoever, unless the code is specifically released by the owner of the patents in the first place, which may then forbid later patent infringement suits on compliant derivative works. This again very much depends on the exact wording of the license, and the patent still remains an independent entity.

B) RCU is okay to use and there will be no possible patent-related problems, because it's LGPL

I have no idea where this comes from. The LGPL paragraphs 11 and 12 specifically do not grant you any right whatsoever regarding patents held over what the code (liburcu in this case) does, it actually says that, if faced with patent infringement suits, you must try to comply with both the suit, as well as the license concerning distribution, meaning you either geographically restrict the software in such a case or stop distributing it altogether. Just because there are LGPL implementations of RCU (and others exist under various other licenses, like in the Linux kernel under the GPL v2.0), doesn't automatically mean that you're granted full usage of the patents on the RCU technique, patents which are fully filed, existing and valid, from Wikipedia: "The technique is covered by U.S. software patent 5,442,758, issued August 15, 1995 and assigned to Sequent Computer Systems, as well as by 5,608,893, 5,727,528, 6,219,690, and 6,886,162. The now-expired US Patent 4,809,168 covers a closely related technique."
As such, the fact an LGPL implementation of RCU exists, doesn't automatically grant you any right upon the RCU patents themselves, nor does it make them automatically freely usable for other implementations.
The fact that Paul McKenney provides a GPL implementation in the kernel may be of help here, as the main patent holder, his offering a GPL licensed implementation does protect users of said GPL implementation and derivatives, again under what the GPL defines as such, from any patent claims.
Regarding the GPL: "This means that a patent holder who distributes a software package incorporating his patent can no longer assert that patent against people who distribute that package further or incorporate the package in their own product. Asserting a patent restricts the rights granted by the GPL and therefore is not permitted. This means that a competitor is now free to incorporate that package in his own product without having to pay any royalty to the patent holder. Of course that part of the product (and all other parts based on that part) will have to be made available under the GPL."
If such then directly translates to the LGPL user-space implementation is unclear, but given the involved parties it's very likely. It still doesn't mean any other, new RCU implementation has any rights on the RCU patents, those are still there and valid. You either need to base your work directly on the available GPL/LGPL code and release it under the same license, or get explicit permission from the patent holders.

C) There may be a patent on the non-blocking list or its delete-bit

Harris actually patented the whole thing. I'm not sure at all about the delete-bit alone, it can trivially be shown that the technique of using the unused bits of a pointer to store information was widely known and used before the 2000 patent. Just take a look at Lisp machines and Tagged pointers. Several implementations exist, work on extending this was done by various sources, there is code and books on this ("The Art of Multiprocessor Programming"). I have no idea what this means from a legal point of view. Non-profit use and research seem to be fully okay. My own code is not a 1:1 implementation of what Harris describes, I use a two-dimensional list, providing KeyNodes at intervals to start re-traversal from a shorter, guaranteed point, and I handle restart of traversal differently, trying a tighter path first.

D) There may be a patent on SMR using Hazard Pointers

There is a patent application, no patent. No idea here either, it is used and extended in other papers (RCU+HP, Ref-counts+HP). Several implementations exist, under various licenses, even of the derivative papers... I am using the concepts too.
In any case, I have to compliment Maged Michael for his papers, those are awesome, very clear and well written.

E) I'm intentionally mis-informing and deceiving users of my library

Hell, NO! As I explained above, software patents are just a non-issue here, it's something you just don't really think about, other than to laugh at Slashdot, ArsTechnica & co. news about the latest patent granted in the US on warm water and double-clicking an icon. With this blog post, linked on the library's home-page, I'm remedying this for the concerned US citizen.

I believe patents on ideas and abstract concepts, especially software, are fundamentally wrong, they realistically only protect the lazy implementor. Especially with the situation as it is now in the US, realistically, shut down your computer and search for a new job, maybe something involving nature (but they're patenting that stuff too...), because I'd really like for you to prove that just glibc, Gnome, KDE are completely safe from any patent-related question. Even if you own the patent yourself, you can't be totally sure no-one else has patented something similar before, and even less sure if and what that means for you. Even the big players have no real idea what's going on, just look at the various browser vendors and Google on VP8 / H264, or take a look at this graph and tell me how long it took you to either explode in laughter, amusedly shake your head, or both.

A few more resources on this:

In the meantime, I'll happily continue coding on my open-source library, learning new things, experimenting and benchmarking and having fun. And I hope others find this freely given work useful, and may use the library themselves, because it's there and works and may make their life easier.

Posted by Luca Longinotti on 08 Jul 2011 at 11:57
Categories: Rig, CompSci, Software Comments

UZH Informatik Zusammenfassungen, Semester 1/2 (HS2010/FS2011)

Seeing as all exams for this semester are finally done, today I busied myself by sorting all the accumulated papers and notes. Since they might be useful to somebody in years to come, I decided to scan all the Zusammenfassungen (summaries) I did during the last two semesters at UZH and post them on-line.
I've created a separate page to hold all my UZH related work, that I'll update as the years go on.

Posted by Luca Longinotti on 17 Jun 2011 at 19:20
Categories: UZH Comments

Brother MFC printers Maintenance Mode

Today my Brother MFC-8860DN printer just decided that, after a paper jam in the ADF, which was quickly fixed, any scanning related functionality would simply be denied...
Even turning it off and on again, pulling the plug for half an hour, nothing helped: as soon as it booted, it just displayed "Please wait" on the display and anything scanning related was refused, printing still worked though.
After some searching on the awesome Internet, I found out that Brother printers have a Maintenance Mode, which can be used to reset the printer when its software gets stuck.

1) To enter Maintenance Mode, turn the printer off and turn it on while holding Menu pressed, you can easily recognize if it worked, as it writes "Maintenance Mode" in big letters and flashes the display.

2) You can now enter codes using the numerical pad, just entering the code is enough, you don't have to press anything else but the numbers, there's no confirmation key.
Here the important codes:

  • 01 - Parameter Init
  • 91 - Parameter Init
  • 77 - Status Page
  • 99 - Exit & Reset

Now, surprisingly, even if 01 and 91 have the same name and display the same thing, they don't reset the printer the same way, at least in my case. 91 seems to be a softer reset than 01, since it didn't work in my case, whereas 01 did and fully reset the printer. 99 seems to be the exit & reset command.
So I deduce more or less the following combinations:

  • 99 - very soft reset
  • 91, 99 - soft reset
  • 01, 99 - hard reset

Basically if your printer face-plants, trying 01, 99 should be your safest bet, as it fully resets the printer; this also means you'll have to set it up again, but other than checking the time and the network settings, there's not much to do, but alas I don't use the Fax, which needs a few more settings to work.

Posted by Luca Longinotti on 17 Jun 2011 at 19:04
Categories: Hardware Comments


For those that don't read LWN, this is so awesome, an Ubuntu-Manga, about a high-school's sys-admin club! Totally hilarious, and being a Manga, of course two thirds of the sys-admin club are cute girls, clearly using Linux and MacOS X (in fact, the brunette works only on terminals and hates anything non-text-based), while the lone dude is a Windows user.
Just a little excerpt: "W-- What sorcery did you use?" (to install Ubuntu so quickly) "The magic of click forward, click forward, and... click finish?" ROFL! And it just gets better. Have fun reading!

Posted by Luca Longinotti on 20 May 2011 at 13:38
Categories: CompSci Comments

Arr! Ye olde Facebook!

Ahahaha, thanks to a couple of friends, I found out today that you can set "English (Pirate)" as a language in Facebook, which results in a really unique experience, totally awesome!

I also added a Blogroll on the right, where I link to other blogs I follow myself, pretty much all of them very technically oriented.

Posted by Luca Longinotti on 17 May 2011 at 19:41
Categories: Longi, CompSci Comments

SSD crazy fast!

Finally replaced the old HD with a SSD I bought in January on my workstation, an OCZ Vertex 2 in 3.5" format, so that it fits in the hot-swap trays I've got.
It's actually surprising that so few vendors have 3.5" editions, as that's what practically all desktops, workstations and servers do have, especially considering hot-swap trays and similar drive bays.
Sure, with 2.5" you can pack more stuff into new-generation servers, but those are still incredibly expensive, and it makes sense on laptops, but that's pretty much it.
Anyway, the results are there: disk operations are crazy fast compared to before. Boot is incredibly fast, actually with OpenRC now, so fast that getting an IP via DHCP was the dominant factor, and changing to a static IP eliminated that one too.
I'm very satisfied with this, and ext4 with the 'discard' option (TRIM support) seems to work perfectly fine.

On the Rig front, I've not done much: some more work went into testing, the typeinfo stuff was completely removed, and a few more checks with regards to sizes and permitted flags were added.

Another project that I'll probably tackle soon is writing a build system that doesn't suck, and that tries to really be minimal, and not support the world and more, it just needs to generate Makefiles (and Visual Studio/Eclipse support probably too). The build itself is left to the relevant tools, this just really needs to gather info about where we're running and the features we want, make that info available to the user (some header file), and generate appropriate Makefiles, which don't depend back on the generator itself, so that you can also just generate generic Makefiles and not need to have the generator installed on every system with all its dependencies. I mostly want to get rid of CMake and its horrible mess of half-baked modules. Anyone wants to help here? It's going to be in Python, and it should support only C/C++ builds.

Posted by Luca Longinotti on 13 May 2011 at 10:10
Categories: Hardware, Rig, Software Comments

Rig 2011/05/02

This week's Rig status update:

  • MLOCK/MRWLOCK: added functions to discover if a lock is held or not, clarified documentation wrt recursive locking, and fixed a possible wrap-around bug in MLOCK and an incorrect error return in MRWLOCK
  • SMR: ported it to use MLOCK instead of its own micro-lock scheme
  • Changed rig_thread_id() to start at 1 for the main thread and not to use 0 at all. This aligns it with some OS implementations, leads to better performance, and fixes a bug in MLOCK, which uses the 0 ID to signal "no-thread-owns-me"
  • Changed default hash algorithm to MurmurHash 3
  • Added support for tests, using the great Check framework for C Unit-Testing, and using CMake's CTest to run them
  • Added optional testing support to the Gentoo ebuild (USE=test + FEATURES=test)

Posted by Luca Longinotti on 02 May 2011 at 08:00
Categories: Rig, C99 Comments

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