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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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