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[23.128.96.18]) by mx.google.com with ESMTP id 125si20855071pff.12.2021.10.05.02.44.34; Tue, 05 Oct 2021 02:44:47 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=casper.20170209 header.b="gnT1M/Cp"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233693AbhJEJoV (ORCPT + 99 others); Tue, 5 Oct 2021 05:44:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232658AbhJEJoU (ORCPT ); Tue, 5 Oct 2021 05:44:20 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C66EFC061745 for ; Tue, 5 Oct 2021 02:42:29 -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=SROZdM74rJINda6efh3/x7QvGWrv4vfLmeneC/gxc0Q=; b=gnT1M/Cprqagurm0L8AhF6akt7 5QYSfLNib7V0LsBfYtkr2RdPMGGCx7gqCeGKVm3ugJq3rCbb5PAfZymNnlNOzYerskU77bfUl9IjP 64qHLybq5EoQLdKcpjoCUKJcvH7DxJopkrLTfUu/qY3FC9+mQ8oVTVpn8pIrKI/OMU+RgFeGwwZhR efZ/KROF2KscbOs18sBvwcL8MbwgxDtglkUftF0pQ/eVCudcjdSNhJZAEhiXBPBh7HnpooeO/vZam 9tPhzwCk5xbTkWnQbcbGXRXBvNhvzdH97vDKREkW+PxmdyLSeV5PPiXPxYiuTURYFVsRfoXzpQtt6 TDUB/YFA==; 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 #2 (Red Hat Linux)) id 1mXgwZ-000Bp5-G8; Tue, 05 Oct 2021 09:41:10 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 86FB33002DE; Tue, 5 Oct 2021 11:41:02 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6F6B2202A012E; Tue, 5 Oct 2021 11:41:02 +0200 (CEST) Date: Tue, 5 Oct 2021 11:41:02 +0200 From: Peter Zijlstra To: Mel Gorman Cc: Vincent Guittot , Mike Galbraith , Ingo Molnar , Valentin Schneider , Aubrey Li , Barry Song , Srikar Dronamraju , LKML Subject: Re: [PATCH 2/2] sched/fair: Scale wakeup granularity relative to nr_running Message-ID: References: <20210920142614.4891-1-mgorman@techsingularity.net> <20210920142614.4891-3-mgorman@techsingularity.net> <22e7133d674b82853a5ee64d3f5fc6b35a8e18d6.camel@gmx.de> <20210921103621.GM3959@techsingularity.net> <20210922132002.GX3959@techsingularity.net> <20210922150457.GA3959@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210922150457.GA3959@techsingularity.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 22, 2021 at 04:04:57PM +0100, Mel Gorman wrote: > On Wed, Sep 22, 2021 at 04:15:27PM +0200, Vincent Guittot wrote: > The reason I used SCHED_TUNABLESCALING_NONE for the changelog is that > the exact values depend on the number of CPUs so values are not even > the same across the range of machines I'm using. sysctl_sched_latency, > sysctl_sched_min_granularity sysctl_sched_wakeup_granularity are all > scaled but the ratios remain constant. It might make sense to reconsider the whole scaling thing FWIW. It used to be that desktop systems had 'small' number of CPUs (<=8) and servers had more. But today it's not uncommon to have 32-64 CPUs in a desktop system. And even LOG scaling gets us into stupid numbers for the latencies.