I got another email from my friend with the thesis that processors will become ever more homogeneous as time goes on, while I believe in a relative heterogenezation (is that a word?) of computer architecture with many special-purpose accelerators and helper processors. This argument is put forward in a previous blog post. In this round, the arguments for homogenization are from the gaming world.
The Multicore Expo US 2008 is taking place next week (April 1-3) in Santa Clara, CA. I was originally slated to talk there, but since I am going to the Embedded Systems Conference a few weeks later it was too much travel in too short a time frame to do. I happy that Ross Dickson, a senior technology specialist at Virtutech could take my place. He will do just as good a job as I would, and he also has his own session to present at the Expo.
Our talk will be on how approximate you can be in simulating multicore computers, and still get useful results out from the software running on the simulator. It is something that we at Virtutech have spent a lot of time working on, and we want to bring our results to a wider community. Really exciting to present, and it is a pity that I could not be there myself.
I attended a DATE 2008 open exhibition panel discussion on multicore programming, organized by Gary Smith EDA. The panel was a few people short, and ended up with just Simon Davidmann of Imperas, Grant Martin of Tensilica, and Rudy Lauwereins of IMEC. A user representative from Ericsson was supposed to have been there but he never arrived. Overall, the panel was geared towards data-plane processing-type thinking, and a bit short on internal dissonance.
I write this on (cramped, poor service Economy class SAS) the flight from Tokyo to Copenhagen. The aircraft attendants just told us that there are some issues with the movies in the in-flight entertainment system, and they will need to take down the system and reboot it. This process is supposed to take some twenty minutes! Nothing to be upset about, really, and likely totally unrelated to anything important for flying the plane. But still, needing twenty minutes for a reset is a bit much for something like this… makes Windows look positively fast in comparison. I guess it has to do with initializing some 200 individual screen units.
Anyway, in the end the system was up partially. All recent feature movies were missing (but the selection of older movies was intact), and the forward and downwards-looking cameras were inaccessible. Apart from that, it appeared to function normally. Interesting that it can be partially broken like that.
I am just back from my first ever trip to Tokyo, and it was a very interesting experience. I am very impressed by the Tokyo train system, and I cannot understand why some foreigners seem to avoid it and use taxis instead. All stations have signs in English (at least all that I visited in Tokyo), and the system is mostly very reliable and predictable. There are some things that I would have like to know before I came there, however, which were not entirely obvious.
Continue reading “Travel Tip: Tokyo Trains”
In a paper from USENIX 2007 by Microsoft Researchers Onur Mutlu and Thomas Moscibroda present a working “denial of service” attack for multicore processors. The idea is simple: since there is no fairness or security designed into current DRAM controllers, it is quite feasible for one program in a multicore system to hog almost all memory bandwidth and thus reduce or deny service to the others. There is no direct attack on software programs, just stealing the resources that they all need to share for all to work.
Continue reading “Multicore Denial-of-Service Attack”