From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A79DC43603 for ; Thu, 19 Dec 2019 02:58:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 13A5F222C2 for ; Thu, 19 Dec 2019 02:58:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726881AbfLSC6X (ORCPT ); Wed, 18 Dec 2019 21:58:23 -0500 Received: from shelob.surriel.com ([96.67.55.147]:39546 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726751AbfLSC6W (ORCPT ); Wed, 18 Dec 2019 21:58:22 -0500 Received: from imladris.surriel.com ([96.67.55.152]) by shelob.surriel.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92.3) (envelope-from ) id 1ihm0p-0007dX-AP; Wed, 18 Dec 2019 21:58:03 -0500 Message-ID: <37ec5587dbb4035b883e5a69b56da4cc67f0e5ff.camel@surriel.com> Subject: Re: [PATCH] sched, fair: Allow a small degree of load imbalance between SD_NUMA domains From: Rik van Riel To: Mel Gorman , Vincent Guittot Cc: Ingo Molnar , Peter Zijlstra , pauld@redhat.com, valentin.schneider@arm.com, srikar@linux.vnet.ibm.com, quentin.perret@arm.com, dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com, hdanton@sina.com, parth@linux.ibm.com, LKML Date: Wed, 18 Dec 2019 21:58:01 -0500 In-Reply-To: <20191218154402.GF3178@techsingularity.net> References: <20191218154402.GF3178@techsingularity.net> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-4rPGTmvcJU+DU3UvKApY" User-Agent: Evolution 3.34.2 (3.34.2-1.fc31) MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-4rPGTmvcJU+DU3UvKApY Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2019-12-18 at 15:44 +0000, Mel Gorman wrote: > + /* > + * Ignore imbalance unless busiest sd is close > to 50% > + * utilisation. At that point balancing for > memory > + * bandwidth and potentially avoiding > unnecessary use > + * of HT siblings is as relevant as memory > locality. > + */ > + imbalance_max =3D (busiest->group_weight >> 1) - > imbalance_adj; > + if (env->imbalance <=3D imbalance_adj && > + busiest->sum_nr_running < imbalance_max) { > + env->imbalance =3D 0; > + } > + } > return; > } I can see how the 50% point is often great for HT, but I wonder if that is also the case for SMT4 and SMT8 systems... --=20 All Rights Reversed. --=-4rPGTmvcJU+DU3UvKApY Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEKR73pCCtJ5Xj3yADznnekoTE3oMFAl365zkACgkQznnekoTE 3oM92wgAsI4/q4OHfp1ABuRwhg8iu8LPAi4JOZC/AldUOdNwRZfcWw7kAGBKpeBP WRY8Boxo4Mig3D8W3qHTAWKrW+hxjuQsOBq6oGpqE9GG/TWjtV0kkeUH32ikLFxC TxUSVEMlPR5DLUe5nhksZlfnBWvhpUrPMqFPQeZDsU1EnboPajCczuOJw/j7UeI5 9uspMvvZSPgBW5YFympWXbOmkG4QdPFq/UWLrrRsrkaJFBMTfF4dDlklBCjn5wBx xckJW3w2CQVqROt514APCN8/xd9ATidIdZ/ZhqRGu+NfVbYDdIk++zkSJuVvYVYk E/QvmfLwgSPPlcTWOwnWoDyV4iHvdQ== =FMp3 -----END PGP SIGNATURE----- --=-4rPGTmvcJU+DU3UvKApY--