From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Bavier <bavier@cray.com>
Subject: Re: fftw runtime cpu detection
Date: Fri, 6 Apr 2018 10:02:32 -0500
Message-ID: <20180406150232.GU105827@pe06.us.cray.com>
References: <20180405221329.GT105827@pe06.us.cray.com> <87sh883gko.fsf@gnu.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Return-path: <guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org>
Received: from eggs.gnu.org ([2001:4830:134:3::10]:50920)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <prvs=6279d15bc=bavier@cray.com>) id 1f4Ssy-0002ZR-Kf
	for guix-devel@gnu.org; Fri, 06 Apr 2018 11:02:41 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <prvs=6279d15bc=bavier@cray.com>) id 1f4Ssu-000157-NG
	for guix-devel@gnu.org; Fri, 06 Apr 2018 11:02:40 -0400
Received: from esa1.cray.iphmx.com ([68.232.142.33]:44217)
	by eggs.gnu.org with esmtps (TLS1.0:RSA_ARCFOUR_SHA1:16) (Exim 4.71)
	(envelope-from <prvs=6279d15bc=bavier@cray.com>) id 1f4Ssu-000129-DB
	for guix-devel@gnu.org; Fri, 06 Apr 2018 11:02:36 -0400
Content-Disposition: inline
In-Reply-To: <87sh883gko.fsf@gnu.org>
List-Id: "Development of GNU Guix and the GNU System distribution."
	<guix-devel.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/guix-devel>,
	<mailto:guix-devel-request@gnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/archive/html/guix-devel/>
List-Post: <mailto:guix-devel@gnu.org>
List-Help: <mailto:guix-devel-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/guix-devel>,
	<mailto:guix-devel-request@gnu.org?subject=subscribe>
Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org
Sender: "Guix-devel" <guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org>
To: Ludovic =?iso-8859-1?Q?Court=E8s?= <ludovic.courtes@inria.fr>
Cc: guix-devel@gnu.org

On Fri, Apr 06, 2018 at 10:05:43AM +0200, Ludovic Courtès wrote:
> Hello Eric,
> 
> Eric Bavier <bavier@cray.com> skribis:
> 
> > I recently discovered that the FFTW library can do runtime cpu
> > detection.  In order to do this, the package needs to be configured to
> > build SIMD "codelets", like how our 'fftw-avx' currently does.  Then,
> > based on the instruction support detected at runtime, make those
> > kernels available to the fftw "planner" for execution.
> 
> That’s really good news!  Thanks for testing it.
> 
> The patch LGTM.  Can you confirm that the planner won’t ever try to use
> the AVX2 codelets, for instance when running the test suite on an x86_64
> box that lacks AVX2?

Yes, I've successfully run 'make check' on an sse2-only machine where
'--enable-avx' and '--enable-avx2' where configured.  I'll check on an
i686 machine tonight.

> If that’s the case, I’d be in favor of pushing this patch to core-updates.

Great.  I'll do some more testing.  Should I send a finalized patch to
guix-patches when it's ready?

-- 
Eric Bavier, Scientific Libraries, Cray Inc.