From mboxrd@z Thu Jan 1 00:00:00 1970 From: Efraim Flashner Subject: Re: parallelizing more actions Date: Sat, 11 Nov 2017 18:49:29 +0200 Message-ID: <20171111164929.GG1815@macbook41> References: <20171109090559.GF1815@macbook41> <878tfdjbw2.fsf@gnu.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="+ZmrHH5cGjskQnY1" Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:35477) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eDYyP-00030x-HJ for guix-devel@gnu.org; Sat, 11 Nov 2017 11:49:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eDYyK-0001rv-HT for guix-devel@gnu.org; Sat, 11 Nov 2017 11:49:37 -0500 Content-Disposition: inline In-Reply-To: <878tfdjbw2.fsf@gnu.org> 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: Ludovic =?utf-8?Q?Court=C3=A8s?= Cc: guix-devel@gnu.org --+ZmrHH5cGjskQnY1 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Nov 11, 2017 at 12:25:01PM +0100, Ludovic Court=C3=A8s wrote: > Hi Efraim, >=20 > Efraim Flashner skribis: >=20 > > While rebuilding glibc-final on aarch64 I realized that the 'strip phase > > took 235 seconds. The relevant code for 'strip from gnu-build-system is > > in guix/build/gnu-build-system.scm, starting at line 340, with the > > actual stripping starting at 398. When I changed 'for-each' to > > 'par-for-each' the time dropped from 235 seconds to 215, about an 8.5% > > savings. I'm pretty sure most of that time was spent failing to strip > > certain files, but it is still a savings. >=20 > Is it on a spinning hard disk or an SSD? My guess is that most of the > time is I/O, and that parallelizing doesn=E2=80=99t buy us much (indeed, = 8.5% is > not that much, far from a linear speedup.)=20 >=20 It was on eMMC, so basically an SSD. > So I=E2=80=99m mildly reluctant to parallelizing this particular piece of= code. >=20 > Thanks, > Ludo=E2=80=99. --=20 Efraim Flashner =D7=90=D7=A4=D7=A8=D7=99=D7=9D = =D7=A4=D7=9C=D7=A9=D7=A0=D7=A8 GPG key =3D A28B F40C 3E55 1372 662D 14F7 41AA E7DC CA3D 8351 Confidentiality cannot be guaranteed on emails sent or received unencrypted --+ZmrHH5cGjskQnY1 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEoov0DD5VE3JmLRT3Qarn3Mo9g1EFAloHKhQACgkQQarn3Mo9 g1ENFg/+IJ6kBQDE7ai5aG2eC/uXlqFgTzTxoiDU7cd/Z5dx4bQmNTlPOD3pw+9i QQTN9PxjtKNssVnNH3dASFJ8d+14Yj8Z5jcMcXc09BT8LSZc4jtoyAZhvJ1dGc5K 1WVaWD8LTb+1GILbU5CLb+Luo1lx1U/vSR3KmjHxNdi4Ka1uUsMY6yipe+Dn/SVA 30OiTIeXRghb4P8GgIQ0L4S6w8V0M0UMsO+v2xx8aKqoo9ncM+vL0y7CU3MGJeqx 1Me0dSct70uiNZz4lh5scCv1xlh22YNmgY8o9CnIWiq/c59/Jzedlvr/X4SnzI68 Ys7heOVzebQHw5BAE0yQaPm9TCGjUtAghcmKZLyS66cXysos9D2lkDQUc277kM3A hD4HL3eijt4rX6CneWF00jEefGOo+rUfpxrsNNeJ8b+VTvize2NspozMGxQbOi+Q yr2ZW6n4iEBEVtkikmnyH830gVkJv9vl8kLhxZlLkYjyMokqyT/zbw8RNRFwh8Pu DbEx/LsmgaFfDDRdRoZEJaq6tshuoVfYEflSQ9Rs0AH6tXsSfx/gwIY9Y3zml49Z DP/j8SsvS7kGyuMhgpM9Esqv8JvGAPHjqxiwY3DIEvy0EDvb3MUubJGSwgdig64v ESbNAr6VatHqIgBqOq02DFOLHxTl7Iauxsmpng8VBqJ7CXOs/14= =/UUq -----END PGP SIGNATURE----- --+ZmrHH5cGjskQnY1--