From: "Stefan Kanthak" <stefan.kanthak@nexgo.de>
To: "Rich Felker" <dalias@libc.org>
Cc: "Szabolcs Nagy" <nsz@port70.net>, <musl@lists.openwall.com>
Subject: Re: [musl] [PATCH #2] Properly simplified nextafter()
Date: Sun, 15 Aug 2021 18:29:08 +0200 [thread overview]
Message-ID: <FC3AE92153FD428B82DC324E6F64842A@H270> (raw)
In-Reply-To: <20210815154843.GH13220@brightrain.aerifal.cx>
Rich Felker <dalias@libc.org> wrote:
> On Sun, Aug 15, 2021 at 05:19:05PM +0200, Stefan Kanthak wrote:
>> Szabolcs Nagy <nsz@port70.net> wrote:
>>
>> > * Stefan Kanthak <stefan.kanthak@nexgo.de> [2021-08-15 09:04:55 +0200]:
>> >> Szabolcs Nagy <nsz@port70.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!
Stefan
next prev parent reply other threads:[~2021-08-15 16:41 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-10 6:23 [musl] [PATCH] " Stefan Kanthak
2021-08-10 21:34 ` Szabolcs Nagy
2021-08-10 22:53 ` Stefan Kanthak
2021-08-11 2:40 ` Rich Felker
2021-08-11 15:44 ` Stefan Kanthak
2021-08-11 16:09 ` Rich Felker
2021-08-11 16:50 ` Stefan Kanthak
2021-08-11 17:57 ` Rich Felker
2021-08-11 22:16 ` Szabolcs Nagy
2021-08-11 22:43 ` Stefan Kanthak
2021-08-12 0:59 ` Rich Felker
2021-08-11 8:23 ` Szabolcs Nagy
2021-08-13 12:04 ` [musl] [PATCH #2] " Stefan Kanthak
2021-08-13 15:59 ` Rich Felker
2021-08-13 18:30 ` Stefan Kanthak
2021-08-14 4:07 ` Damian McGuckin
2021-08-14 22:45 ` Szabolcs Nagy
2021-08-14 23:46 ` Szabolcs Nagy
2021-08-15 7:04 ` Stefan Kanthak
2021-08-15 7:46 ` Ariadne Conill
2021-08-15 13:59 ` Rich Felker
2021-08-15 14:57 ` Ariadne Conill
2021-08-15 8:24 ` Damian McGuckin
2021-08-15 14:03 ` Rich Felker
2021-08-15 15:10 ` Damian McGuckin
2021-08-15 14:56 ` Szabolcs Nagy
2021-08-15 15:19 ` Stefan Kanthak
2021-08-15 15:48 ` Rich Felker
2021-08-15 16:29 ` Stefan Kanthak [this message]
2021-08-15 16:49 ` Rich Felker
2021-08-15 20:52 ` Stefan Kanthak
2021-08-15 21:48 ` Rich Felker
2021-08-15 15:52 ` Ariadne Conill
2021-08-15 16:09 ` Rich Felker
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