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 261BBC433EF for ; Tue, 5 Oct 2021 09:33:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0311761425 for ; Tue, 5 Oct 2021 09:33:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233572AbhJEJfV (ORCPT ); Tue, 5 Oct 2021 05:35:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59554 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233365AbhJEJfU (ORCPT ); Tue, 5 Oct 2021 05:35:20 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 128E5C061745 for ; Tue, 5 Oct 2021 02:33:30 -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=GQy6jrQzp7SQEfSgsx40GCt9tDyuUPnWczLZw1jnZNM=; b=HSxIC9GgQfg66qlEOswlFup3Q3 DGqP9JGzvBA8Znx5BmbfKC24ItVpjHNw/TB/52bkvorLcGM+6B7OwFZMn3H55dPUw58PrqajVmFNr tLKnrB9GmGKX+ztz6EejW7DE/F7QulOymymh7Vh4vXVdabCkcpC1KF89CuhS0UVHMHCpmdV5y0Mgw Y7KLONVLtgbiWB2I6UYiC6gl8oUJNKbXppQCV8zZHE3jPKqszDqP59CvbIWZq5i/w37Zjdi7fq4Z7 upf56TJED4wC7B0aDyFMtVkBj8EkfkAtB9VCcTespXwrQNWquws9+YdXmtqFqER/i6tEtOdyPRm2k X8LOiApw==; 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 1mXgns-000BNi-O4; Tue, 05 Oct 2021 09:32:24 +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)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5F4F4300233; Tue, 5 Oct 2021 11:32:04 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 21FD7202A012E; Tue, 5 Oct 2021 11:32:04 +0200 (CEST) Date: Tue, 5 Oct 2021 11:32:04 +0200 From: Peter Zijlstra To: Mel Gorman Cc: Mike Galbraith , Ingo Molnar , Vincent Guittot , 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210922132002.GX3959@techsingularity.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 22, 2021 at 02:20:02PM +0100, Mel Gorman wrote: > > Note that the TuneD throughput-performance profile allows up to 15ms > for sysctl_sched_latency (ignoring scaling) but there is no explanation > why such a long period was necessary or why sched_latency_ns is also > not adjusted. The intent may have been to disable wakeup preemption > or it might be an oversight. An internet search for instances where > sysctl_sched_wakeup_granularity parameter are tuned to high values offer > either no explanation or a broken one. FWIW, if one wants to disable wakeup preemption, we've got SCHED_BATCH for that.