From: Joseph Myers <joseph@codesourcery.com>
To: Paul E Murphy <murphyp@linux.ibm.com>
Cc: Paul Zimmermann <Paul.Zimmermann@inria.fr>, <libc-alpha@sourceware.org>
Subject: Re: faster expf128
Date: Mon, 22 Jun 2020 21:18:55 +0000 [thread overview]
Message-ID: <alpine.DEB.2.21.2006222114250.24721@digraph.polyomino.org.uk> (raw)
In-Reply-To: <a5cf1511-d1d1-39b2-ea28-fd84eb5c5361@linux.ibm.com>
On Mon, 22 Jun 2020, Paul E Murphy via Libc-alpha wrote:
> On 6/22/20 6:02 AM, Paul Zimmermann wrote:
> > I have written some expf128 for x86_64 that is more than 10 times faster
> > than
> > the current glibc/libquadmath code [1] (see slide 21 of [2]).
>
> I would highly recommend running the benchmarks against ppc64le or s390x
> before replacing the existing implementation. I think it would improve the
Specificall, ppc64le *on POWER9*, as POWER9 and s390x are the two
supported configurations with hardware support for binary128, and where
it's thus plausible that an implementation based on floating-point
operations is faster than one using only integer operations.
As documented in the manual, glibc supports _Float128 for powerpc64le,
x86_64, x86, ia64, aarch64, alpha, mips64, riscv, s390 and sparc (most of
those are architectures where long double has binary128 format; for
powerpc64le the long double format depends on compiler options and
configuration, and for x86_64, x86 and ia64 _Float128 is always a
different format from long double).
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2020-06-22 21:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 11:02 Paul Zimmermann
2020-06-22 13:59 ` Paul E Murphy
2020-06-22 21:18 ` Joseph Myers [this message]
2020-06-24 6:22 ` Paul Zimmermann
2020-06-24 17:39 ` Joseph Myers
2020-06-26 10:09 ` Szabolcs Nagy
2020-06-29 22:39 ` Joseph Myers
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