Finally I had time to look through the source too and while the benchmark is probably hopelessly unfair to ithreads, not working correctly with ithreads and totally artificial, the program at least makes a lot more sense to me. It seems to be a synthetic benchmark of the Coro package (and as you will see this can explain a lot)

The coro queues are limited to 512 entries. So after filling the first queue (which would happen if creation of the matrices is faster than the multiplication, what I assume) the 4 producer threads just keep the queue filled. Waiting a few rounds before timing is sensible because before the queue is filled the timing won't be stable.

Measuring >5 seconds makes sense as well. You need a minimum time to get enough accuracy on the time measurement and since CPUs get faster with time you can't just use a fixed number of rounds.

Coro also seems to stop all coroutines if one of them calls exit(), so no need to stop the threads when the main program finishes.

The term $count / ($N * $N * (time - $t)) is how many multiplications (or matrix cells) per second the benchmark can process. Definitely not a random value

It is a synthetic benchmark with random cell values. So if matrix b isn't transformed it really doesn't matter. Even the wiping of the result in the ithread version doesn't matter, but probably wasn't meant that way, either a bug or the wiping was simply unknown to the benchmark writer

No question this algorithm doesn't make sense as a real world solution. As a synthetic benchmark of Coro it works, as a worst case example for ithreads probably too.

I don't know what the copying is about. It makes sense to unshare data if you do a lot of operations on it because shared data is slower, but one mulitiplication isn't a lot. Maybe this was included to simulate some optimizations

Cleaning up of the queues is not necessary because (again) this isn't a real solution to a problem but a synthetic benchmark. The only result anyone is interested in is the time it takes

In reply to Re^7: If I am tied to a db and I join a thread, program chrashes by jethro
in thread If I am tied to a db and I join a thread, program chrashes by lance0r

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