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Old 2020-08-11, 11:54   #6
axn's Avatar
Jun 2003

113528 Posts

Originally Posted by retina View Post
The machines periodically spend a few minutes doing no useful work in an attempt to find a faster FFT strategy. But any gains it can find are not enough to justify shutting things down for so many minutes.
The autobenchmark doesn't run everyday. Once it has gathered sufficient number (10?) of benchmarks for a given FFT size, the benchmarks will stop (until test requiring a new FFT size is received).

There can be a significant difference (10%?) between fastest FFT implementation and default FFT implementation. Of course, with high probability, the very first autobenchmark will find the best implementation.

Subsequent ones are just an insurance that the conditions during the first one wasn't representative (like what OP experienced, ironically).
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