Date: Sun, 15 Aug 2021 12:49:04 -0400 From: Rich Felker <dalias@...c.org> To: Stefan Kanthak <stefan.kanthak@...go.de> Cc: Szabolcs Nagy <nsz@...t70.net>, musl@...ts.openwall.com Subject: Re: [PATCH #2] Properly simplified nextafter() On Sun, Aug 15, 2021 at 06:29:08PM +0200, Stefan Kanthak wrote: > Rich Felker <dalias@...c.org> wrote: > > > On Sun, Aug 15, 2021 at 05:19:05PM +0200, Stefan Kanthak wrote: > >> Szabolcs Nagy <nsz@...t70.net> wrote: > >> > >> > * Stefan Kanthak <stefan.kanthak@...go.de> [2021-08-15 09:04:55 +0200]: > >> >> Szabolcs Nagy <nsz@...t70.net> wrote: > >> >>> you should benchmark, but the second best is to look > >> >>> at the longest dependency chain in the hot path and > >> >>> add up the instruction latencies. > >> >> > >> >> 1 billion calls to nextafter(), with random from, and to either 0 or +INF: > >> >> run 1 against glibc, 8.58 ns/call > >> >> run 2 against musl original, 3.59 > >> >> run 3 against musl patched, 0.52 > >> >> run 4 the pure floating-point variant from 0.72 > >> >> my initial post in this thread, > >> >> run 5 the assembly variant I posted. 0.28 ns/call > >> > > >> > thanks for the numbers. it's not the best measurment > >> > >> IF YOU DON'T LIKE IT, PERFORM YOUR OWN MEASUREMENT! > > > > The burden of performing a meaningful measurement is on the party who > > says there's something that needs to be changed. > > I offered you two patches which speed a rather simple function by a > measured factor of 5 and 7 respectively. IF YOU DOUBT THESE NUMBERS, > PROVIDE YOUR OWN! I really have better things to be doing than putting up with repeated toxic interactions for the sake of a supposed miniscule improvement in something nobody has identified as having any problem to begin with. If you want to engage constructively, you're welcome to. This is not it. Rich
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