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 3F702C433F5 for ; Mon, 8 Nov 2021 11:14:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 258D861350 for ; Mon, 8 Nov 2021 11:14:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239131AbhKHLRj (ORCPT ); Mon, 8 Nov 2021 06:17:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52952 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237964AbhKHLR0 (ORCPT ); Mon, 8 Nov 2021 06:17:26 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B1CAC06120A for ; Mon, 8 Nov 2021 03:14:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=6LeBVXEEkfDG4XZfeocFTtH7tQHJXwcvP1bIONx7BfY=; b=JgIx4gtY4DvoxTEpdZB5cPSdef TWAZGjv6MvjFep+EqydrBYraYk1j+wBracHkKPVi01ej04s9ewmHP52dj1HGSsRuojfxEZa7a+e4o p0b4KVHw7aaE3TLSfBi2r+9EWtt9nWNbxbDYp5xEEuwVYTpfGqRC5hXb7u9R6Zyys4tDUU6MjmS+n Vntgm07nRQJ3ewjZLCFncPCE1GOVCtd7KsMvRIe+kAzYfb4+ZzeDOXXd6sbAmqxi/ezysuaL475Dd /6fz4FiqowjtxZc3fKBJ2Quu1IdnifxpZY61yUJkOetfQTtQHrSfmUq3F/8xxxJemF9BdyjpLiV7X qjnHHivg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mk2bd-00EsBO-MG; Mon, 08 Nov 2021 11:14:31 +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 1770530030B; Mon, 8 Nov 2021 12:14:28 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id DAC63202A012E; Mon, 8 Nov 2021 12:14:27 +0100 (CET) Date: Mon, 8 Nov 2021 12:14:27 +0100 From: Peter Zijlstra To: Mel Gorman Cc: Ingo Molnar , Vincent Guittot , Valentin Schneider , Aubrey Li , "Srinivasan, Sadagopan" , LKML Subject: Re: [PATCH] sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCs Message-ID: References: <20211028130305.GS3959@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211028130305.GS3959@techsingularity.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 28, 2021 at 02:03:05PM +0100, Mel Gorman wrote: > @@ -1926,8 +1926,8 @@ static void task_numa_find_cpu(struct task_numa_env *env, > src_running = env->src_stats.nr_running - 1; > dst_running = env->dst_stats.nr_running + 1; > imbalance = max(0, dst_running - src_running); > - imbalance = adjust_numa_imbalance(imbalance, dst_running, > - env->dst_stats.weight); > + imbalance = adjust_numa_imbalance(imbalance, env->dst_cpu, > + dst_running, env->dst_stats.weight); Can we please align at (0 ? > > /* Use idle CPU if there is no imbalance */ > if (!imbalance) { > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c > index 4e8698e62f07..08fb02510967 100644 > --- a/kernel/sched/topology.c > +++ b/kernel/sched/topology.c > @@ -644,6 +644,7 @@ static void destroy_sched_domains(struct sched_domain *sd) > DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc); > DEFINE_PER_CPU(int, sd_llc_size); > DEFINE_PER_CPU(int, sd_llc_id); > +DEFINE_PER_CPU(int, sd_numaimb_shift); Why does it make sense for this to be a per-cpu variable? Yes, I suppose people can get creative with cpusets, but what you're trying to capture seems like a global system propery, no? At most this seems to want to be a sched_domain value. > DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared); > DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa); > DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing); > @@ -672,6 +673,20 @@ static void update_top_cache_domain(int cpu) > sd = lowest_flag_domain(cpu, SD_NUMA); > rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); > > + /* > + * Save the threshold where an imbalance is allowed between SD_NUMA > + * domains. If LLC spans the entire node, then imbalances are allowed > + * until 25% of the domain is active. Otherwise, allow an imbalance > + * up to the point where LLCs between NUMA nodes should be balanced > + * to maximise cache and memory bandwidth utilisation. > + */ > + if (sd) { > + if (sd->span_weight == size) > + per_cpu(sd_numaimb_shift, cpu) = 2; > + else > + per_cpu(sd_numaimb_shift, cpu) = max(2, ilog2(sd->span_weight / size * num_online_nodes())); > + } > + > sd = highest_flag_domain(cpu, SD_ASYM_PACKING); > rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd); I think I'm with Valentin here, this seems like something that wants to use the sd/sd->child relation. That also makes this the wrong place to do things since this is after the degenerate code. Perhaps this can be done in sd_init(), after all, we build the thing bottom-up, so by the time we initialize the NODE, the MC level should already be present. I'm thinking you can perhaps use something like: if (!(sd->flags & SD_SHARE_PKG_RESROUCES) && (child->flags & SD_SHARE_PKG_RESOURCES)) { /* this is the first domain not sharing LLC */ sd->new_magic_imb = /* magic incantation goes here */ }