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altf4 / untwister

Seed recovery tool for PRNGs
GNU General Public License v3.0
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Decreasing performance with extra threads #19

Closed altf4 closed 9 years ago

altf4 commented 9 years ago

Untwister seems to be decreasing in performance with extra threads. Not sure why. Perhaps some overhead with concurrency? Here is a sample on my AMD Penom II X6 (6 physical cores):

1 Thread: ~53881.6/sec 2 Threads: ~13661.7/sec 3 Threads: ~17843.6/sec 4 Threads: ~16478.2/sec 5 Threads: ~4191.44/sec 6 Threads: ~4440.59/sec

Really curious numbers... I can definitely confirm that CPU usage is where you would expect it to be. IE: The threading definitely happens.

altf4 commented 9 years ago

I think this was a side effect of the glib-rand bug. (Issue #15) Once I fixed that, this behavior has gone away. Also, the performance is an order of magnitude better. So, I think I'll call this closed.

New performance numbers on commit e917995c8c90f528b3bfb3f86cfc3323c7a6c289 from the same machine on glibc-rand: 1 Thread: ~185654/sec 2 Threads: ~363283/sec 3 Threads: ~530081/sec 4 Threads: ~665008/sec 5 Threads: ~821106/sec 6 Threads: ~989939/sec