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October 25, 2014 15:50Subject:

significant slowdown in float arithmeticMessage ID:

20141025155040.GR5204@iabyn.comI just noticed that the nbody benchmark is about 25% slower in 5.21.5 compared with 5.21.4 (and older). It seems that floating-point arithmetic is considerably slower after this commit (although I haven't looked at why): commit 0f83c5a4f945d1919a6ff6564a3a18375f15f949 Author: Jarkko Hietaniemi <jhi@iki.fi> AuthorDate: Mon Sep 22 21:37:38 2014 -0400 Commit: Jarkko Hietaniemi <jhi@iki.fi> CommitDate: Tue Sep 23 08:29:53 2014 -0400 Avoid mixing Inf/NaN with IV/UV. It really makes no sense to ask what's the IV/UV of this Inf/NaN, or turn on the IOK/UV flags (private or public). For example, my $n = 0.0; my $a = 0.1; $n += $a*$a + $a*$a + $a*$a for 0..10_000_000; These two miniperls are ones built non-threaded, -O2 just before and after that commit: $ time ~/tmp/miniperl-413 ~/tmp/p; time ~/tmp/miniperl-412 ~/tmp/p real 0m1.874s user 0m1.870s sys 0m0.000s real 0m2.296s user 0m2.292s sys 0m0.001s -- "Strange women lying in ponds distributing swords is no basis for a system of government. Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony." -- Dennis, "Monty Python and the Holy Grail"Thread Next

**significant slowdown in float arithmetic**by Dave Mitchell- Re: significant slowdown in float arithmetic by Jarkko Hietaniemi
- Re: significant slowdown in float arithmetic by Dave Mitchell
- Re: significant slowdown in float arithmetic by Jarkko Hietaniemi
- Re: significant slowdown in float arithmetic by Jarkko Hietaniemi
- Re: significant slowdown in float arithmetic by Dave Mitchell
- Re: significant slowdown in float arithmetic by Dave Mitchell
- Re: significant slowdown in float arithmetic by Jarkko Hietaniemi
- Re: significant slowdown in float arithmetic by Dave Mitchell
- Re: significant slowdown in float arithmetic by Jarkko Hietaniemi
- RE: significant slowdown in float arithmetic by bulk 88
- Re: significant slowdown in float arithmetic by bulk88
- Re: significant slowdown in float arithmetic by Dave Mitchell
- Re: significant slowdown in float arithmetic by Jarkko Hietaniemi

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