Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755662AbcDJUY7 (ORCPT ); Sun, 10 Apr 2016 16:24:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44320 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755626AbcDJUY4 (ORCPT ); Sun, 10 Apr 2016 16:24:56 -0400 Message-ID: <1460319890.25336.2.camel@redhat.com> Subject: Re: [regression] cross core scheduling frequency drop bisected to 0c313cb20732 From: Rik van Riel To: Mike Galbraith , "Rafael J. Wysocki" , Peter Zijlstra Cc: "Rafael J. Wysocki" , "Rafael J. Wysocki" , LKML , Linux PM list , Doug Smythies Date: Sun, 10 Apr 2016 16:24:50 -0400 In-Reply-To: <1460302797.4383.44.camel@gmail.com> References: <1460092854.4051.1.camel@gmail.com> <20160408064510.GK3448@twins.programming.kicks-ass.net> <1460098254.5582.17.camel@gmail.com> <2428384.mEkP3EOpsR@vostro.rjw.lan> <20160409110729.GS3448@twins.programming.kicks-ass.net> <1460302797.4383.44.camel@gmail.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-gvuGWzP62NibU80pxy57" Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2386 Lines: 70 --=-gvuGWzP62NibU80pxy57 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sun, 2016-04-10 at 17:39 +0200, Mike Galbraith wrote: > On Sat, 2016-04-09 at 14:31 +0200, Rafael J. Wysocki wrote: > >=20 > > On Sat, Apr 9, 2016 at 1:07 PM, Peter Zijlstra > g> > > wrote: > > >=20 > > > On Fri, Apr 08, 2016 at 10:59:59PM +0200, Rafael J. Wysocki > > > wrote: > > > >=20 > > > > On Friday, April 08, 2016 08:50:54 AM Mike Galbraith wrote: > > > > >=20 > > > > > On Fri, 2016-04-08 at 08:45 +0200, Peter Zijlstra wrote: > > > > >=20 > > > > > >=20 > > > > > > Cute, I thought you used governor=3Dperformance for your > > > > > > runs? > > > > > I do, and those numbers are with it thus set. > > > > Well, this is a trade-off. > > > >=20 > > > > 4.5 introduced a power regression here so this one goes back to > > > > the previous > > > > state of things. > > > Just for my elucidation; how can gov=3Dperformance have a 'power' > > > regression? > > Because of what is used as the "default" idle state most of the > > time. > >=20 > > C1 was used before 4.5 and that changed to polling in 4.5. > Should the default idle state not then be governor dependent?=C2=A0=C2=A0= When I > set gov=3Dperformance, I'm expecting box to go just as fast as it can > go > without melting.=C2=A0=C2=A0Does polling risk CPU -> lava conversion? Current CPUs can only have some cores run at full speed (turbo mode) if other cores are idling and/or running at lower speeds. It may be time to stop pretending that gov=3Dperformance actually results in better performance on current CPUs, since it may inhibit entire levels of turbo mode. --=20 All Rights Reversed. --=-gvuGWzP62NibU80pxy57 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABCAAGBQJXCraTAAoJEM553pKExN6DxagIAJQBthceCqIpGjtaZjCINSft TB8HaHautTi7fE0xsLyU1znsvdBn8lar+OvY/xMl0y7O3hGZZzIuPZB1bghd8B+Q MwTReARBb76vFHSwMN6xXqpUNY9vBVJemNWiMUecPSIMndq+blQWRC5C9Rs2YboV wSTeWF4uKbvwq67KGLXjaqR/CKJAjuTYBD3IrYwHylDCwxvCPWcl8zGaLse3rax4 Bv4mP4YOiDcZDAuzkzOp2MJ7P5TO6no8p+tnezkm7ddF6Fqia07g5Ky/C24njFho oy+PfWcZ1upW4dHFsoc2PJVkkp3Evsp1rOV7Fi2+wWFaiN6/T/OkxSErgKCLarc= =yPcK -----END PGP SIGNATURE----- --=-gvuGWzP62NibU80pxy57--