Computer simulation, programming, software, technology, research, and more (since 2007)
Game engine development company Valve has a nice presentation up on their website about how they attacked multithreading. It is a nice example of how to solve multicore programming for a particular domain by the classic layered approach.
Continue reading “Valve Source Engine Multicore Port (presentation comment)”
Vista just gave me an interesting error message: running a serious Java program required it to turn off the Aero interface. Interesting. What can Java have done to deserve that?
I just got a funny error message from YouTube. Searching for quite innocuous terms like “Ã…nglok” a highly trained group of Monkeys kept popping up. Read on for screen dump.
The TimeSys Embedded Linux Podcast (also called LinuxLink Radio) is a nice listen about embedded computing using Linux. Sometimes they are a bit too open-source centric, though, and ignore very good tools that live in the classic commercial world. One such example is the recent episode 20 on debugging tools, where they totally ignore modern high-powered hardware-based debugging.
Continue reading “Hardware Debug Support & LinuxLink PodCast”
In a report from FTF Paris 2007, Info World makes some interesting comments on security and locking-down of mobile devices. Info World » Blog Archive » ‘Flat IP’ mobile networks face new security challenges:
Continue reading “FTF Paris: Debug connections threat to secure network devices”
The new version of Trango’s embedded “secure virtualizer” for the ARM Cortex-A9 MPCore is an interesting solution in that it directly applies virtualization technology to the issue of migrating solutions (complete software stacks) from single-core to multicore. The details are a bit sketchy in just how this is done, there is some hardware support in recent ARM architectures, but a little bit of adaptation of a guest OS using paravirtual techniques are likely not a blocker. It also touches on security, implemented using ARM’s trustzone technology. All in all, I think this is a typical example of something that we are going to see much more of.
One common use-case for multicore processing on the desktop and elsewhere is “doing many things at the same time”. You could be running many user-interface programs at once, like the “typical today’s teenager template” of tens of IM clients, web sessions, email conversations, music and video players, downloading movies, etc. Or it is a more business-like background indexing of harddrives, backups being taken, downloading large business files, compiling software, updating source code repositories, etc.
I have been doing both of these modes to some extent, and the main problem with them at least on a PC is that while the processors might be good at multitasking and sharing the CPU load, my IO system is annoyingly non-parallel.
I just read a EETimes report from a panel at the Power.org Developers Conference (actually, it is more accurately called the Power Architecture Developers Conference, of PADC), about programming multicore processors for the embedded market. Note that I was not there in person, so I can only take the few quotes in the article and comment on them. The main conclusions are that:
In a sense, blaming the market for not having the good sense to adapt new tools to tackle multicore.
I don’t think things have to be that bleak.
Continue reading “Power.Org Dev Con: C Domination a Problem for Multicore”
In my work at Virtutech trying to explain Simics and its simulation philosophy, it is often a struggle to get people to accept that what seems like pretty brutal simplifications of the world actually work quite nicely. Recently, I found a nice analogy in a golf game/simulator. The type where you swing a real club and send a real golf ball through the air.
Continue reading “Golf Games and Computer Simulations”
Joel Spolsky is always worth a read, and in his post Strategy Letter VI he has a lot of smart things to say about how to consider programming. His basic message is that if you optimize your code too much to work well and fit in the memory of a current machine, by the time that you are done, you find yourself run over by competitors that just assumed machines would be faster and used the same programming time to implement cooler products.
I just have to take issue with this.
Continue reading “Comment on Joel Spolsky and Programming to “Moores Law””
A question that pops up quite often when computer architects and representatives from firms like Intel encounter a crowd today is but just what do you need more computing power for????. Most regular users are fairly happy with the speed at which they process words, surf the web, read email, do IP phone calls, crunch numbers in Excel, and other common tasks. It is hard to perceive the need for more speed in everyday tasks, unlike a decade or two ago when you could definitely ask for improvement. I remember scrolling a page in PageMaker on a Mac SE (8Mhz 68000). You counted the clicks and waited for the screen to jump, redraw, jump, redraw, stabilize… quite a different experience from working with modern computers and far more complex software that still responds instantaneously to almost any work.
Continue reading “Applications that can make use of more compute power (e.g., iPod Video)”
The “Handbook of Real-Time and Embedded Systems” (ToC, Amazon, CRC Press) is now out. I and my university research colleague and friend Andreas Ermedahl have written a chapter on worst-case execution time analysis. We talk some about the theories and techniques, but we try to discuss practical experience in actual industrial use. Both static, dynamic, and hybrid techniques are covered.
I just got my personal copy, but my first impression of the book overall is very positive. The contents seems quite practical to a large extent, not as academic as one might have feared. Do check it out if you are into the field. It is not a collection of research paper, rather instructive chapters informed by solid research but with applications in mind.
A short update to the previous posting on how to compress video for the nano.
It turns out that the “iPod video” profile of Nero Recode is half aimed at showing video from your iPod on external devices. That’s the only good reason for the “high” resolution. I typically got a video size of 15MB per minute with these settings, which quickly fills up even gigabytes of space.
Using the “iPod Video-AVC” profile instead is optimized for viewing on the Nano itself and not on some external device. The resolution is down to 320×200-240 depending on source aspect ratio. And the resulting files are only about 5MB per minute, much more manageable for carrying a large video library on an iPod. I cannot see any difference in the quality of the output…
Update (2007-September-23): The default iPod-AVC setting has some issue with rapid cross-fades between scenes. To get around this, I set the quality settings to “2-pass” and “highest quality” in the detailed settings you can make in the second screen before moving on to actually encode things. This created very nice looking video that had no problems handling even the previously broken fades.
The cost was even more compute time. I think the current settings takes some 5 to 10 hours per material hour to encode (on my Athlon XP 2700+, not exactly a screamer by current standards).
Spotted at EETimes.com – Odd move: AMD plans three-core CPU . Interesting that someone in the mainstream finally breaks the 1-2-4-8 progression that seems to be the norm.
This is not in my self-assigned range of topics, but I like when other people put up their helpful notes of how to accomplish some task that I am researching. Thus, I feel obliged to do the same when I have tested something reasonably new.
The task at hand here is “how to get video into an iPod Nano”.
Continue reading “Off-Topic: Getting video onto an iPod Nano (3G/Video)”