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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 09BDFC433E0 for ; Mon, 1 Mar 2021 15:46:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BCD8764DDE for ; Mon, 1 Mar 2021 15:46:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237376AbhCAPqT (ORCPT ); Mon, 1 Mar 2021 10:46:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237075AbhCAPqO (ORCPT ); Mon, 1 Mar 2021 10:46:14 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 532AEC061756 for ; Mon, 1 Mar 2021 07:45:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=TSa8nsScEP0oQJAOUkZDicDP/piGiwm3u3sQvk/SQeI=; b=bCI0/hzskyfJ+m3pl398c373zv T+QUahHIyJYVFlZ5EhYyfc85PdP1QyT8z+nYu+y8eCrcp1hdhacG1v6x5uXDSUgEcylWEHl43/czQ BjnknzV0aadkSR0TSSOK/z5h5TS7JysYkqgRZXWVPZiVE3+naQ1hrL4hsZjGTG4xWjha6ax2qRYQ5 NJYouITN5s7r4/WmL//wIMFVHVkYOQ7kvkwZr8/ORsgrRyWmZwXTL3mSw4UILfuhuCkDqPwIvMnpN kArq23T7wZQ0aDu9BHpMzHmrVmfjIda1S04lTuSVbNdQTHgdG3owRChrDkLVYGZ9J1PPVtJcoAwuW tebOnF3A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lGkiy-00Fu9w-HT; Mon, 01 Mar 2021 15:44:50 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0C923301959; Mon, 1 Mar 2021 16:44:43 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EB1EB2059E79F; Mon, 1 Mar 2021 16:44:42 +0100 (CET) Date: Mon, 1 Mar 2021 16:44:42 +0100 From: Peter Zijlstra To: Rik van Riel Cc: Srikar Dronamraju , Ingo Molnar , LKML , Mel Gorman , Thomas Gleixner , Valentin Schneider , Vincent Guittot , Dietmar Eggemann , Michael Ellerman , Michael Neuling , Gautham R Shenoy , Parth Shah Subject: Re: [PATCH] sched/fair: Prefer idle CPU to cache affinity Message-ID: References: <20210226164029.122432-1-srikar@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="2JpPWwCpCiHiKfCh" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --2JpPWwCpCiHiKfCh Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Feb 27, 2021 at 02:56:07PM -0500, Rik van Riel wrote: > On Fri, 2021-02-26 at 22:10 +0530, Srikar Dronamraju wrote: > > + if (sched_feat(WA_WAKER) && tnr_busy < tllc_size) > > + return this_cpu; >=20 > I wonder if we need to use a slightly lower threshold on > very large LLCs, both to account for the fact that the > select_idle_cpu code may not find the single idle CPU > among a dozen busy ones, or because on a system with > hyperthreading we may often be better off picking another > LLC for HT contention issues? >=20 > Maybe we could use "tnr_busy * 4 < > tllc_size * 3" or > something like that? How about: tnr_busy < tllc_size / topology_max_smt_threads() ? --2JpPWwCpCiHiKfCh Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEv3OU3/byMaA0LqWJdkfhpEvA5LoFAmA9C+oACgkQdkfhpEvA 5Lr4sw/8CHIRe96iDw8Z0JJAEw3nZ7kn+aDNlrrJiZouqveXeylMFdp+7rh9cZ8b iJX23CwYvC5w/mY1qetiphLgZeY8kpERNrFZT6ZAaRfSXY2qU4U20sO2OybZhJtI BJuTmAmWifVBciQbvHW1a2r0GQHv61Y5ibu854DgbqRCFIr4zQh/onLSq5GUQ1+i o6rhtFu32TYR8cYXvNpp0XlP7GlWd0eDEz5aUKMpw1BUUQ6+UBNtKnbxCT8Fkn2H XYig+LvXUHmA5ambIJS2ZvZYTE8Ic4fK7ySKTePWD3Vj1/qc7PGRAvhm0xtRB5Me Hc7wLEDIyO6m5rwx2bM5JoNErRUp/Dt2RK/KXkSjDkGhtypcmzVkDnU3hNW4CUJU NxS3izeaWp5KPumnzqYYlsH5QKVFV0RdIV+yoPrYlPt6sz2A7uQUCuOmj6GgKhUB 1JkE4WXzSkZhY+fzSCumCg2p/Dzt4+Bg2jNjFrygRSG/kFQSvLVr01LADVpE0+Bd qy/7GmSgVwXe9UDdVBfDNWSDXOM1Ht4XUe/mz53Bec1wF87hWj54LbZH4EIx4EV/ 0vIP22cFC428emRIEZdne0HcME4AkaCg+9DE8RCI2JpvA0LBPWTrdUsBBAh5zLuZ 3qgNkN/Rnntpv8LiOad0jW4H5BaXn3D/niJzwBjE4X2q5WuYLlM= =4Aam -----END PGP SIGNATURE----- --2JpPWwCpCiHiKfCh--