Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759355AbXIMRGS (ORCPT ); Thu, 13 Sep 2007 13:06:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752015AbXIMRGK (ORCPT ); Thu, 13 Sep 2007 13:06:10 -0400 Received: from viefep18-int.chello.at ([213.46.255.22]:28840 "EHLO viefep33-int.chello.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751760AbXIMRGJ (ORCPT ); Thu, 13 Sep 2007 13:06:09 -0400 Subject: Re: [announce] CFS-devel, performance improvements From: Peter Zijlstra To: Roman Zippel Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Mike Galbraith In-Reply-To: References: <20070911200459.GA6974@elte.hu> <20070913075258.GA9173@elte.hu> <20070913142842.GA26016@elte.hu> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-ljIxIjWczria6IeI+dO9" Date: Thu, 13 Sep 2007 19:06:05 +0200 Message-Id: <1189703165.21778.258.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1671 Lines: 55 --=-ljIxIjWczria6IeI+dO9 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Thu, 2007-09-13 at 18:50 +0200, Roman Zippel wrote: > I never claimed to understand every detail of CFS, I can _guess_ what=20 > _might_ have been intended, but from that it's impossible to know for=20 > certain how important they are. Let's take this patch fragment: >=20 delta_fair =3D se->delta_fair_sleep; we slept that much > - /* > - * Fix up delta_fair with the effect of us running > - * during the whole sleep period: > - */ > - if (sched_feat(SLEEPER_AVG)) > - delta_fair =3D div64_likely32((u64)delta_fair * load, > - load + se->load.weight); if we would have ran we would not have been removed from the rq and the weight would have been: rq_weight + weight so compensate for us having been removed from the rq by scaling the delta with: rq_weight/(rq_weight + weight) > - delta_fair =3D calc_weighted(delta_fair, se); scale for nice levels --=-ljIxIjWczria6IeI+dO9 Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBG6W39XA2jU0ANEf4RAr3+AJ9AVgnJheVN29qwEXZQkEiYFsM3egCbBHqB olfg48R1Q4dzeG4CtrXv6Yw= =HBFK -----END PGP SIGNATURE----- --=-ljIxIjWczria6IeI+dO9-- - 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/