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[Octave-bug-tracker] [bug #60928] Performance of sort unexpectedly slow


From: anonymous
Subject: [Octave-bug-tracker] [bug #60928] Performance of sort unexpectedly slow for DIM=2
Date: Mon, 16 Aug 2021 16:32:35 -0400 (EDT)
User-agent: Mozilla/5.0 (Android 8.0.0; Mobile; rv:91.0) Gecko/91.0 Firefox/91.0

Follow-up Comment #15, bug #60928 (project octave):

Good God! Yes, that makes perfect sense now. The reason why only dimension 2
on were affected was the special code path for dimension 1, not a CPU cache
effect. The while loop explains the quadratic behavior spotted by mleitner,
and also why DIM=3 was n times as fast as DIM=2, because the stride length was
n times higher inside the while loop, not because of copy construction. And
the fix certainly makes all the timings far more consistent. My
congratulations to rik5 for isolating the real problem and fixing it!

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