The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Thursday, August 08, 2019

The “Tonya Harding Solution” to computer benchmarks

… we knew we had to do more to truly earn those extra credit points. Luckily, I had one final optimization idea:

The Tonya Harding Solution: The benchmark program works by calling the optimized function, calling the naive function, and comparing the two times. And this gave me a truly devilish idea. I added some code to calc_depth_optimized that created a child process. That child process would wait for calc_depth_naive to start running, then send a SIGUSR1 signal to the benchmark process. That signal would interrupt calc_depth_naive and jump to a special signal handler function I'd installed:

void our_handler(int signal) {
    // if you can't win the race, shoot your opponent in the legs
    sleep(image_size * 4 / 10000);
}

So while we did implement a number of features that made our program faster, we achieved our final high score by making the naive version a whole lot slower. If only that 4 had been a 5 …

CS 61C Performance Competition

I'll have to hand it to Carter Sande for literally beating the competition in benchmarking.

(Although it wasn't Tonya Harding who did the attack, but Shane Stant, hired by Harding's ex-husband Jeff Gillooly who attacked Nancy Kerrigan with a police baton and not a gun. Harding herself claims she had nothing to do with the attack.)

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