Tuesday, December 19, 2006

Computer power consumption

In a previous post, I promised to measure the power consumption of my PCs. I finally did this, and got the following results:

Computer off, power supply off: ......... 0 Watt
Computer off: ........................... 7 Watt
Windows idle after startup: ............ 64 Watt
Book generator running: ............... 112 Watt
Monitor (Flatscreen) alone: ............ 36 Watt

This result was slightly surprising for me. I would have expected my PC to use more power than 112 Watt when running Cake - after all, it is using the CPU fully and also using the harddisk quite a bit. What are all these 350 Watt power supplies for, I wonder? The result also changes my checkers programming economics post: My book generator now "only" uses 2.7kWh per day, or 0.35$ a day. Since I have been computing opening books for about 4 years now, that puts the worth of the opening book at 500$.
On the other hand, 112 Watt is still a lot, given that we should be moving towards the 2000-Watt-Society - I am using over 5% of my power consumption for something rather useless like checkers book building....

I also measured the power consumption of my other PCs. Unsurprisingly, my other desktop PC is quite similar to the book generator PC, while my old laptop with a 1.4GHz Centrino processor uses only 23.5 Watt idle and 39 Watt when running Cake. Turning off the LCD screen saves another 6 Watt. Here's an interesting thing: on my desktop PC (with a AMD 64 3400+), running Cake costs about 50 Watt more compared to the idle state of the PC for nearly 2000 kN/s. On my laptop, running Cake at about 70% of that speed costs only 15 Watt, or about 3 times less. That means that my laptop is producing about twice as many nodes/second with the same amount of energy. Unfortunately, I measured these numbers before I got my new Core Duo machine, so I have no figures for that.

Monday, December 18, 2006

Core Duo!

It's been a long time since I last bought a new computer (21 months, to be exact, a record for me in the last 10 years!) - but I just did it again: I got myself a new laptop with an Intel Core Duo CPU - unfortunately not one of the even better Core 2 Duos. However, even this machine is absolutely great! Cake runs about as fast on my Core Duo at 2GHz as on my Athlon 64 at 2GHz. But the cool thing is that I can run two instances of Cake at the same speed, if I want to. Not that this really helps me in any way... it just shows why these dual core machines are so cool. The days of single core CPUs are numbered (as far as PCs go, anyway), and the first quad-cores for consumers are already on the market. Which gives me a bit of a headache, because it means that I should try to rewrite Cake so that it can use these new CPUs with multiple cores! All good chess programs have this capability, but the only checkers program that I know of that could use multiple processors was Chinook. However, the speedup from multiple processors there was quite lousy compared to what is reported for chess programs. For chess, it's something like 1.9x faster for dual cores and 3.5x faster for quad-cores, for Chinook it was approximately 3x faster on 16 CPUs [1]. It's not quite clear to me whether checkers is inherently tougher to parallelize than chess or whether the implementation in Chinook was poor. Any opinions?

Friday, December 01, 2006

Usage Statistics for November

Since November 2006, the full 8-piece checkers endgame database is available for download on my website. I checked the usage statistics for my server, and found the following:

Month 2006 traffic
August 7.8 GB
September 67.3 GB
October 93.4 GB
November 142 GB

This means that the 8-piece database is responsible for about a 20-fold increase in data traffic from my website! It also means that the database was downloaded about 60 times. In the same month, CheckerBoard was downloaded 2'500 times, and the opening book 200 times. 60 downloads in one month is not that much, but it still makes me think about something like checkers@home...
For comparison, my 4 in a row program was downloaded 500 times, while Sudoku Champion didn't make it to the top 30 files which I can view.