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Tue Sep 12 18:28:25 2006 GMT: London River Boat Trip to Greenwich
Thu Sep 07 17:30:48 2006 GMT: Alcatel Lucent
Tue Sep 05 18:33:49 2006 GMT: Notting Hill Carnival Pictures
I have finally uploaded some pictures (and here) of last week's Notting Hill Carnival to my digital photo album.
Tue Aug 29 17:23:57 2006 GMT: Notting Hill Carnival
Yesterday, I enjoyed the Notting Hill Carnival in London. I haven't yet been able to put my pictures into the digital photo album, but am planning to do so in the next few days...
Tue Aug 22 17:08:17 2006 GMT: e-mail Address Change
I have been using my @web.de e-mail address for some years now, but having added quite a few services to the cmeerw.org domain (like XMPP and SIP), it's probably time to switch my e-mail address to the cmeerw.org domain as well. The main reason why I haven't done this earlier is that e-mail is quite an important service and should really be implemented in a redundant way. Yet, my Web hosting provider (like most low-cost Web hoster) doesn't provide that redundancy.
So, the solution I have now come up with is to use my (also low-cost) virtual server as a secondary MX (mail exchange) and forward e-mails on the primary and secondary MX to two different mailboxes (in my case I use a mailbox on my Web hoster's server and an aim.com account).
Of course, my web.de e-mail address will continue to work for some time, but you really should start using my new unified cmeerw.org address.
Sat Aug 19 12:10:18 2006 GMT: mcabber 0.8.0
This week mcabber 0.8.0 has been released. The reason why I mention this release is because I have contributed some fixes to significantly reduce CPU usage. In previous versions, there was a pretty tight busy-waiting loop that was responsible for up to around 2000 context switches per second. This has been replaced by a proper select loop.
Tue Aug 08 17:07:30 2006 GMT: Linux threading models compared: LinuxThreads and NPTL
Vikram Shukla has published an article on IBM's developerWorks site comparing Linux threading models. Yet, in my opinion this article is misleading and contains a few errors. To start with, it actually compares threading libraries (i.e implementations) and not threading models (as both libraries implement a 1:1 threading model based on the clone system call which basically is a generalisation of the fork system call).
Vikram is right in claiming that Linux initially didn't have any thread support, but the clone system call was specifically introduced to allow the implementation of threading libraries. Although the POSIX threading API was implemented in user-space, scheduling was done by the kernel (as all threads were proper kernel threads). The article further points out the limitations of LinuxThreads that lead to the development of NPTL, but it misses a few important points here. In essence, the kernel support for threading in NPTL is merely an evolution of the early clone-based threading support, i.e. clonehas been extended and a few system calls have been added to move parts of the threading library from user-space into the kernel.
The author also seems to have found the silve bullet for thread safety: "You should also keep in mind that while building your library with LinuxThreads, use the -D_REENTRANT compile-time flag. This makes the library thread safe." Well, for some definition of "thread safe" this might be true, but, of course, for most definitions of "thread safe" it isn't, -D_REENTRANT will only ensure that the multi-threaded C-library is being used (although the preferred flag on Linux is -pthread).
Finally, the last paragraph really looks quite strange and statements like these shouldn't be included in any technical article: "NPTL, being an SMP-oriented design, has drawbacks too. I have seen cases on recent Red Hat kernels where a simple threading application runs fine on a single-processor machine but hangs on SMP. I believe there is still more work to be done on Linux to truly make it scalable to satisfy higher-end applications." This is really just FUD at its worst.
Tue Aug 01 17:16:14 2006 GMT: Llandudno
Fri Jul 28 23:18:39 2006 GMT: Snowdonia Vacation
Thu Jul 20 17:11:20 2006 GMT: Self-service Library
Sun Jul 16 12:42:53 2006 GMT: Croydon Summer Festival
Sun Jul 09 11:28:29 2006 GMT: rise against racism
