Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751857Ab2BOQEr (ORCPT ); Wed, 15 Feb 2012 11:04:47 -0500 Received: from opensource.wolfsonmicro.com ([80.75.67.52]:42898 "EHLO opensource.wolfsonmicro.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750935Ab2BOQEo (ORCPT ); Wed, 15 Feb 2012 11:04:44 -0500 Date: Wed, 15 Feb 2012 08:04:38 -0800 From: Mark Brown To: Peter Zijlstra Cc: Saravana Kannan , Ingo Molnar , Benjamin Herrenschmidt , Todd Poynor , Russell King , Nicolas Pitre , Oleg Nesterov , cpufreq@vger.kernel.org, linux-kernel@vger.kernel.org, Anton Vorontsov , linaro-kernel@lists.linaro.org, Mike Chan , Dave Jones , "Paul E. McKenney" , kernel-team@android.com, linux-arm-kernel@lists.infradead.org, Arjan Van De Ven Subject: Re: [PATCH RFC 0/4] Scheduler idle notifiers and users Message-ID: <20120215160437.GD2996@opensource.wolfsonmicro.com> References: <20120208013959.GA24535@panacea> <1328670355.2482.68.camel@laptop> <20120208202314.GA28290@redhat.com> <1328736834.2903.33.camel@pasglop> <20120209075106.GB18387@elte.hu> <4F35DD3E.4020406@codeaurora.org> <20120211143951.GA24564@sirena.org.uk> <1328971983.11320.5.camel@laptop> <20120211153324.GC31887@opensource.wolfsonmicro.com> <1329313084.2293.105.camel@twins> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="osDK9TLjxFScVI/L" Content-Disposition: inline In-Reply-To: <1329313084.2293.105.camel@twins> X-Cookie: You will be awarded some great honor. User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2588 Lines: 60 --osDK9TLjxFScVI/L Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 15, 2012 at 02:38:04PM +0100, Peter Zijlstra wrote: > On Sat, 2012-02-11 at 15:33 +0000, Mark Brown wrote: > > There's use cases for having this > > stuff offloaded but if you're not doing that stuff then why deal with > > the complication of designing the hardware?=20 > Because doing it in software is more expensive? > Penny-wise pound-foolish like thing.. you make the software requirements > more complex, which results in more bugs (more cost in debugging), more > runtime (for doing the 'software' thing), less power savings. > Esp since all this uC/system-controller stuff is already available and > validated. It's really not - like I say most of the times people have tried to deploy this on embedded systems it's just made everyone more miserable and typically winds up getting turned off or bypassed. The PMICs are much more decoupled from the CPUs and the power control on the SoCs is more fine grained than you seem to see in the desktop market. There's software effort but people are willing to spend that for microamps and all other things being equal they'd typically rather spend it in the software stack they're already working with rather than in a separate stack for a microcontroller. --osDK9TLjxFScVI/L Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJPO9eOAAoJEBus8iNuMP3dIFQP/j6N0/AYlrCYqKT0Uujt6S26 ifZdkc4w8Egox3etMb9nNXhcqohs5og/APuE61ITvflVd0WwRTgDxjx5lFA+5W94 KFJ6t1G+bByC28NfgnRKU0iMZT/uXH4rKWE7pRuxpCnjOetCY6UHqdDQZ+HAe3kP r45tcE7j7OVSP9uHWLAJHiQ4DhfDoWUMNuxGfEOGNhH6qzzM0PuX+cNsrymGTGlc 1hKYP8bfkZzkjh6/HDzKWp+uoB+BMQsrK/YpS98Hor7MRBLoZyduI+DAwg/j6Yug E588ChgrEZTSfMER2NUluPv8i+DhEyzYcGlkTOlh4EnNNS+s0e6M7YexkUestMgZ ac0yuJdmFIUdhuAfGtlw7mc6esIZ1lfEcp8uzmhg7MxoFheoZ0YZd8/l9/O+T199 /NMVXctkRiWPACelBTWhng6DN7Ve4CCReuqL4ZFmMWHE1sZI0ShdGjo6j4mf7Yht XKBETcIKdKbA6NXc9aByMBfPgL3m2O4EOM3mEdoouqiRRwTZBYJYxZ4+JXSxM1d8 Xw+1hrdZDORhJWKsy7j/erwMYN0TC6VscifGa3Mf576eTmKyTMoMXL+8O50RkbRS iAaHhLEV9wHnk10BVdp1vR0d/cPgyNKfyAmlabVvMHdgbMii5cnTju8/w5MQVpY0 MOMtlgCP0277Eltx4d6j =qMnv -----END PGP SIGNATURE----- --osDK9TLjxFScVI/L-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/