From: Wilco Dijkstra via Libc-alpha <libc-alpha@sourceware.org>
To: "Paul A. Clarke" <pc@us.ibm.com>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>,
"libc-alpha@sourceware.org" <libc-alpha@sourceware.org>
Subject: Re: [PATCH v3 5/7] math: Remove powerpc e_hypot
Date: Wed, 10 Nov 2021 14:34:09 +0000 [thread overview]
Message-ID: <VE1PR08MB5599A27A3DE03FC5902CDF4F83939@VE1PR08MB5599.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <20211109192800.GA4930@li-24c3614c-2adc-11b2-a85c-85f334518bdb.ibm.com>
Hi Paul,
> The patches see poorer performance on Power10, also:
Was that with the last patch to remove the redirects as well? The latest version
is still slower even with that on AArch64...
I think the new algorithm will always be slower due to the dependent sqrt and
division. So it's hard to improve unless we only use it for special cases (eg. when
ax and ay are close). Returning sqrt (fma (ax, ax, ay * ay)) is about twice as fast
and gives just over 1 ULP, so we're losing a lot of performance for a small ULP
improvement.
Cheers,
Wilco
next prev parent reply other threads:[~2021-11-10 14:35 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-01 20:20 [PATCH v3 0/7] Improve hypot() Adhemerval Zanella via Libc-alpha
2021-11-01 20:20 ` [PATCH v3 1/7] math: Simplify hypotf implementation Adhemerval Zanella via Libc-alpha
2021-11-01 20:20 ` [PATCH v3 2/7] math: Use an improved algorithm for hypot (dbl-64) Adhemerval Zanella via Libc-alpha
2021-11-01 20:20 ` [PATCH v3 3/7] math: Use an improved algorithm for hypotl (ldbl-96) Adhemerval Zanella via Libc-alpha
2021-11-01 20:20 ` [PATCH v3 4/7] math: Use an improved algorithm for hypotl (ldbl-128) Adhemerval Zanella via Libc-alpha
2021-11-01 20:20 ` [PATCH v3 5/7] math: Remove powerpc e_hypot Adhemerval Zanella via Libc-alpha
2021-11-09 19:28 ` Paul A. Clarke via Libc-alpha
2021-11-10 14:34 ` Wilco Dijkstra via Libc-alpha [this message]
2021-11-10 14:43 ` Paul A. Clarke via Libc-alpha
2021-11-10 14:47 ` Adhemerval Zanella via Libc-alpha
2021-11-11 17:05 ` Wilco Dijkstra via Libc-alpha
2021-11-11 17:13 ` Adhemerval Zanella via Libc-alpha
2021-11-11 19:48 ` Wilco Dijkstra via Libc-alpha
2021-11-11 20:54 ` Adhemerval Zanella via Libc-alpha
2021-11-01 20:20 ` [PATCH v3 6/7] i386: Move hypot implementation to C Adhemerval Zanella via Libc-alpha
2021-11-01 20:20 ` [PATCH v3 7/7] math: Remove the error handling wrapper from hypot and hypotf Adhemerval Zanella via Libc-alpha
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