From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Marusich Subject: Re: fftw runtime cpu detection Date: Fri, 06 Apr 2018 00:54:19 -0700 Message-ID: <87po3cahxw.fsf@gmail.com> References: <20180405221329.GT105827@pe06.us.cray.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:36779) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f4MCb-0004P0-Az for guix-devel@gnu.org; Fri, 06 Apr 2018 03:54:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f4MCY-00076X-8F for guix-devel@gnu.org; Fri, 06 Apr 2018 03:54:29 -0400 Received: from mail-it0-x22f.google.com ([2607:f8b0:4001:c0b::22f]:36809) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1f4MCX-000761-PD for guix-devel@gnu.org; Fri, 06 Apr 2018 03:54:26 -0400 Received: by mail-it0-x22f.google.com with SMTP id 15-v6so656630itl.1 for ; Fri, 06 Apr 2018 00:54:25 -0700 (PDT) In-Reply-To: <20180405221329.GT105827@pe06.us.cray.com> (Eric Bavier's message of "Thu, 5 Apr 2018 17:13:29 -0500") List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org Sender: "Guix-devel" To: Eric Bavier Cc: guix-devel@gnu.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Eric Bavier writes: > I recently discovered that the FFTW library can do runtime cpu > detection. Cool! I'm not familiar with this library, but the patch seems pretty reasonable to me. > 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. So, if we choose the right configure flags at build time (for the given architecture), then at runtime, the software will detect the CPU and either perform better or make more features available. Is that right? I see you added the "--enable-sse" configure flag, and it not present before. Why did you add it? =2D-=20 Chris --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEy/WXVcvn5+/vGD+x3UCaFdgiRp0FAlrHJ6sACgkQ3UCaFdgi Rp0tkQ/7BTMsQvDY9OVePTsv/MctiZTGmRz9/sheLL8hL5SyXFM0uVth3YM3xIQG 4irXHQbl4eb1e2x8Db1D17n3rqY1He1qN3sUh4fPiyXtdxmvZP8PjPz8Pmv8WCv2 qeNvfZurckjdml+SqTTbXWaynT6borVWc/KvWz+EXk2yQHJa0UIAltjsgtUvNmrf ES6+aPDNOxmX37TuTmVMJlMetNWQYEEfloUVEHJVthhkYgvBVUs5otwyhytgU8bf 00qWPZbsW56xRJ51Nyvh6bbUOSZTsRKrYy8cRo9J4yVsNfAtrbQekJtE6/zCbJP4 m+yOe4P3DVFFUUORB+MYMF2p+7Fl+LFLDdCmpVVpQPYNMCal3Nq3JD90utgrwOcb xtRcG3OSBpV9Ioz/bnZpiumE7uFzqL6fksfkETGeeP4tLItCUJ1wQDZE7KJCzM5+ IlLub+0HgBNmE5laa0E4FQ8DE16ynFYPqzW+qvz2jSk3GC2omiKn/LUKO/wqI8fn eqxzKJ1XHfHZDxS/QKf2ZuCVVH52y9kXNwQutPCF9d5AkJZBFedSpkHI0Y744fIp vIH4lJZG4tO2C3cxVtQVbyuOX88SjDCS1AcQJ4L1uqQdl3gKBTCLqao4apnAfQ8k 6PzoFDbvJ/wDh3Rd1Dz5F2yXCJm+rstBStaoF29z6NbPu6/HtD0= =nhzd -----END PGP SIGNATURE----- --=-=-=--