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Server Loads

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Server Loads

Postby montanalow » Tue Feb 23, 2010 3:59 am

I've seen a couple instances online when my bot made an inferior move indicated by a shallow minimax depth, when a better move was indicated at a depth that takes < 0.1s (total) to compute on my Core 2 laptop at home. Should we plan for identical server loads during the tournament, or will there be a less contention for processing time?

EDIT: this seems rare, but I've only noticed because they were game changing idiot moves
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Re: Server Loads

Postby jmcarthur » Tue Feb 23, 2010 5:51 am

I'm seeing similar issues, for the record.
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Re: Server Loads

Postby a1k0n » Tue Feb 23, 2010 5:52 am

We were just discussing this in IRC. I've noticed exactly the same thing; it seems my bot is sometimes getting only 50-100 CPU-milliseconds rather than the full second, because it makes moves that are only found at a certain depth.

Are you running multiple games in parallel on one machine? Can one bot interfere with another bot's CPU slices by spinning while waiting for I/O, or does each bot get a core?
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Re: Server Loads

Postby melkor » Tue Feb 23, 2010 7:59 am

I'm seeing the same issue as well. Also, this seems to fluctuate a lot, at times, my AI is able to go to much higher depth (requiring at least 10x time on my pc) than other times. I'm not sure, but i think that this is causing my AI to exceed the 1s restriction as I'm using the average time taken for each calculation to predict the depth to calculate to for each move.
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Re: Server Loads

Postby henrikno » Tue Feb 23, 2010 8:24 am

I lost a game and couldn't reproduce the results on my machine. This would definitely explain it.
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Re: Server Loads

Postby wtarle » Tue Feb 23, 2010 2:47 pm

Same here
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Re: Server Loads

Postby jeff.cameron » Fri Feb 26, 2010 7:24 am

The machine that's running the tournament is pretty much dedicated to that purpose. It also has 8 cores, and we're not running that many games concurrently. I will look into this and see if perhaps not all the cores are being used, or whether this is due to plain old scheduler strangeness. If it's just scheduler strangeness, then I don't know how we would go about debugging that. Any ideas?
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Re: Server Loads

Postby melkor » Fri Feb 26, 2010 1:36 pm

How many games are you running concurrently? As I said before, I'm using the average time taken for each calculation to decide how much depth I should calculate to. The time taken for say 2000 calculations is fluctuating drastically on the server, because on my pc I never get timeout errors even when I set the time threshold on my AI to make a move within 0.9s. On the server though, I had to set the threshold to 0.03s, after which i did not get any timeout errors for 3 days, but now I'm getting timeouts even on setting it to 0.02s. The most important question is, will you be running so many games concurrently even after the final submission? Because this is affecting my AI and it's too late to make any changes at this point. It would make sense to reduce the number of games being run simultaneously after the final submission.
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