From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <sourceware-bugzilla@sourceware.org>
Received: by sourceware.org (Postfix, from userid 48)
 id 92108385800C; Wed, 24 Feb 2021 09:45:46 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 92108385800C
From: "nsz at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug math/27461] Unixbench/whetstone-double performance regression
 on glibc2.32
Date: Wed, 24 Feb 2021 09:45:46 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: glibc
X-Bugzilla-Component: math
X-Bugzilla-Version: 2.32
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: nsz at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: unassigned at sourceware dot org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: cc
Message-ID: <bug-27461-131-5Hqkc195g1@http.sourceware.org/bugzilla/>
In-Reply-To: <bug-27461-131@http.sourceware.org/bugzilla/>
References: <bug-27461-131@http.sourceware.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://sourceware.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: glibc-bugs@sourceware.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Glibc-bugs mailing list <glibc-bugs.sourceware.org>
List-Unsubscribe: <https://sourceware.org/mailman/options/glibc-bugs>,
 <mailto:glibc-bugs-request@sourceware.org?subject=unsubscribe>
List-Archive: <https://sourceware.org/pipermail/glibc-bugs/>
List-Help: <mailto:glibc-bugs-request@sourceware.org?subject=help>
List-Subscribe: <https://sourceware.org/mailman/listinfo/glibc-bugs>,
 <mailto:glibc-bugs-request@sourceware.org?subject=subscribe>
X-List-Received-Date: Wed, 24 Feb 2021 09:45:46 -0000

https://sourceware.org/bugzilla/show_bug.cgi?id=3D27461

Szabolcs Nagy <nsz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nsz at gcc dot gnu.org

--- Comment #2 from Szabolcs Nagy <nsz at gcc dot gnu.org> ---
1) this benchmark is not representative: it only calls exp with values near
-0.575 and log with values near 0.75 so it's possible that those cases had a
fast path in the old implementation, but that's not relevant in practice.

2) exp@@GLIBC_2.29 is the same as __exp and __exp_finite and __ieee754_exp.
only on x86 there is a difference because the ifuncs are not sorted out: th=
at's
an x86 only issue.

so somebody with the right hw should do a more direct comparision of exp and
log performance (e.g. glibc has its own benchmarks but you can just measure=
 a
loop).
i don't have an x86 with fma the x86 improvement work should be done by
somebody who has.

--=20
You are receiving this mail because:
You are on the CC list for the bug.=