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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8CE4BC433FE for ; Tue, 5 Oct 2021 08:07:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76020610EA for ; Tue, 5 Oct 2021 08:07:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233036AbhJEIJW (ORCPT ); Tue, 5 Oct 2021 04:09:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38986 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232511AbhJEIJU (ORCPT ); Tue, 5 Oct 2021 04:09:20 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 48BEEC061745; Tue, 5 Oct 2021 01:07:30 -0700 (PDT) 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=fTYy+JsPp0Luxwf+jQWWHB2bXvTIbDSFNvdErOAVSfU=; b=TFueyENHYRQaO/5AkXnMZFErfu dCo/57hrVzgG6W8MQiffUDe+6QbULCs0oQlPQ+Swhf359Yk5CiAGmxs3w6wgx5HeCMN/jgPgmzVne wERlayxLdLN4zfJwbHoB72Klc3r0fCHHRGLmRErQHON7MNY6JrtT3btE3ZLydYLBYzErPW6xzea5t IXrppEwU4ltBFfMK6NsboV+UizetAnojTdwFX9g5xRCyNiDtht9g8ShhWiXkplzntmZ6cnov8kCNS 9xJiak0SeGLOS4W6feosLerqZVIPyaMoXL4UpVPrwWn2rY0tO1FZ8edyaHr/BG2BVZ8omonD5kP/6 4gnVLzDg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mXfQr-0007BD-SM; Tue, 05 Oct 2021 08:04:27 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 7AAA198631C; Tue, 5 Oct 2021 10:04:13 +0200 (CEST) Date: Tue, 5 Oct 2021 10:04:13 +0200 From: Peter Zijlstra To: Barry Song <21cnbao@gmail.com> Cc: Tim Chen , Vincent Guittot , Dietmar Eggemann , LKML , Ingo Molnar , Aubrey Li , Borislav Petkov , Daniel Bristot de Oliveira , Ben Segall , Catalin Marinas , Greg Kroah-Hartman , Guodong Xu , "H. Peter Anvin" , Jonathan Cameron , Juri Lelli , "Cc: Len Brown" , ACPI Devel Maling List , LAK , Linuxarm , Mark Rutland , Mel Gorman , msys.mizuma@gmail.com, "Zengtao (B)" , "Rafael J. Wysocki" , Steven Rostedt , Barry Song , Sudeep Holla , Thomas Gleixner , "Rafael J. Wysocki" , Valentin Schneider , Will Deacon , x86 , yangyicong Subject: Re: [PATCH RESEND 0/3] Represent cluster topology and enable load balance between clusters Message-ID: <20211005080413.GL4323@worktop.programming.kicks-ass.net> References: <20210924085104.44806-1-21cnbao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 02, 2021 at 08:09:58PM +1300, Barry Song wrote: > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 7e4651a1aaf4..86821e83b935 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -993,8 +993,13 @@ config SCHED_CLUSTER > bool "Cluster scheduler support" > help > Cluster scheduler support improves the CPU scheduler's decision > + making when dealing with machines that have clusters of CPUs. > + Cluster usually means a couple of CPUs which are placed closely > + by sharing mid-level caches, last-level cache tags or internal > + busses. For example, on Hisilicon Kunpeng920, each 4 CPUs share > + LLC cache tags. This feature isn't a universal win because it > + can bring a cost of slightly increased overhead in some places. > + If unsure say N here. > > config SCHED_SMT > bool "SMT scheduler support" > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index bd27b1cdac34..940eb1fe0abb 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1002,12 +1002,17 @@ config NR_CPUS > to the kernel image. > > config SCHED_CLUSTER > + def_bool y > + prompt "Cluster scheduler support" > help > Cluster scheduler support improves the CPU scheduler's decision > + making when dealing with machines that have clusters of CPUs. > + Cluster usually means a couple of CPUs which are placed closely > + by sharing mid-level caches, last-level cache tags or internal > + busses. For example, on x86 Jacobsville, each 4 CPUs share one > + L2 cache. This feature isn't a universal win because it can bring > + a cost of slightly increased overhead in some places. If unsure > + say N here. That is a really odd addition to a default-y feature. How about I make both: help Cluster scheduler support improves the CPU scheduler's decision making when dealing with machines that have clusters of CPUs. Cluster usually means a couple of CPUs which are placed closely by sharing mid-level caches, last-level cache tags or internal busses.