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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53770C04A95 for ; Sun, 25 Sep 2022 18:05:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230465AbiIYSFV (ORCPT ); Sun, 25 Sep 2022 14:05:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231462AbiIYSFU (ORCPT ); Sun, 25 Sep 2022 14:05:20 -0400 Received: from mail-qt1-x832.google.com (mail-qt1-x832.google.com [IPv6:2607:f8b0:4864:20::832]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0B2D1CB2E; Sun, 25 Sep 2022 11:05:18 -0700 (PDT) Received: by mail-qt1-x832.google.com with SMTP id b23so2920493qtr.13; Sun, 25 Sep 2022 11:05:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=JKE0avk2agse0RfyTYwfmZtHd0Xz4kE8lQXynudu2As=; b=pPEosRMaSEYtfU7ncPPfTGVrG73p1rJV3iAiOcnyzLB3OMEbJxsRKSM55vo3kYlrsP 0XWlin6agoRCfdz3YZdupnxBZxV1pweOIpUts1QHO9HNfufEbFao3Uz0VD2QcEwfB4t2 tZGRN/Dae2PzxR5BKzOz3L2EsbVGHu+sH8xhkc4Tx8RV+hfWadhHLKUukC9aEgdjzy8z O8QIDva69zSGLGY74o9SKpBGh5tqMmfqievfRmhuKHiawC+hL/i7hmuVHjwFvn4zcMvx 0TY4tpSLG5XL+x2fkYw1bH4zRGWRYLuT9y6+QdCR6vL13Fl8wlXTGy/dNUsLtbwwt53L b4tQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=JKE0avk2agse0RfyTYwfmZtHd0Xz4kE8lQXynudu2As=; b=ZQozt131Gt8udUp9naRDwlmnt+ehlaeJ6/Vqn6SewANEVJpEqkhTP2NlkNmOve5Apd EY/7C6uhwXH2+64/3uQRczCHqdd6GOvL/LpcIWVPF4j7XDnqEwDnGRzn/LnujY53EhoC dAbuBfQidTaXbpqc3XPmKCWwusq6bU9d28+Lzrv4+OQq99mpvqQzAoIzQykh4d3mAD7p F7YIZ89ZnN+aWfR9j8CKX8YQqTCG+0n9m0hFgWj0AO6rWz5DQQqSrGsixrb4J9llNC30 AXjUmiuyp3lPs5H5/IvMEJ1bM4qB5KMO23dcf5zChdOSOkinf1oCUpuGTIY39m230yUF xkJA== X-Gm-Message-State: ACrzQf1B6e55dizR1EtFw7c9A9FcZhwUnaGJG10wctQXm5Yo/gDtClyA Z80O+zLzp/f9NqM3W9yUEJA= X-Google-Smtp-Source: AMsMyM6EBZiZ+Y7U/trqNcXvNyJNbSikwbfTJy5j5025u/0IbZIE3wssrJPH/05w2NMvJYAYKMPg5g== X-Received: by 2002:ac8:5c55:0:b0:35b:b8d9:2ff8 with SMTP id j21-20020ac85c55000000b0035bb8d92ff8mr15240964qtj.554.1664129117774; Sun, 25 Sep 2022 11:05:17 -0700 (PDT) Received: from localhost ([2601:4c1:c100:2270:7be8:ebb8:b71d:18b9]) by smtp.gmail.com with ESMTPSA id bq22-20020a05622a1c1600b0035ba48c032asm9388700qtb.25.2022.09.25.11.05.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Sep 2022 11:05:17 -0700 (PDT) Date: Sun, 25 Sep 2022 11:05:16 -0700 From: Yury Norov To: Valentin Schneider Cc: netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, Saeed Mahameed , Leon Romanovsky , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Andy Shevchenko , Rasmus Villemoes , Ingo Molnar , Peter Zijlstra , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Mel Gorman , Greg Kroah-Hartman , Heiko Carstens , Tony Luck , Jonathan Cameron , Gal Pressman , Tariq Toukan , Jesse Brandeburg Subject: Re: [PATCH v4 5/7] sched/topology: Introduce sched_numa_hop_mask() Message-ID: References: <20220923132527.1001870-1-vschneid@redhat.com> <20220923155542.1212814-4-vschneid@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220923155542.1212814-4-vschneid@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Fri, Sep 23, 2022 at 04:55:40PM +0100, Valentin Schneider wrote: > Tariq has pointed out that drivers allocating IRQ vectors would benefit > from having smarter NUMA-awareness - cpumask_local_spread() only knows > about the local node and everything outside is in the same bucket. > > sched_domains_numa_masks is pretty much what we want to hand out (a cpumask > of CPUs reachable within a given distance budget), introduce > sched_numa_hop_mask() to export those cpumasks. > > Link: http://lore.kernel.org/r/20220728191203.4055-1-tariqt@nvidia.com > Signed-off-by: Valentin Schneider > --- > include/linux/topology.h | 12 ++++++++++++ > kernel/sched/topology.c | 31 +++++++++++++++++++++++++++++++ > 2 files changed, 43 insertions(+) > > diff --git a/include/linux/topology.h b/include/linux/topology.h > index 4564faafd0e1..3e91ae6d0ad5 100644 > --- a/include/linux/topology.h > +++ b/include/linux/topology.h > @@ -245,5 +245,17 @@ static inline const struct cpumask *cpu_cpu_mask(int cpu) > return cpumask_of_node(cpu_to_node(cpu)); > } > > +#ifdef CONFIG_NUMA > +extern const struct cpumask *sched_numa_hop_mask(int node, int hops); > +#else > +static inline const struct cpumask *sched_numa_hop_mask(int node, int hops) > +{ > + if (node == NUMA_NO_NODE && !hops) > + return cpu_online_mask; > + > + return ERR_PTR(-EOPNOTSUPP); > +} > +#endif /* CONFIG_NUMA */ > + > > #endif /* _LINUX_TOPOLOGY_H */ > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c > index 8739c2a5a54e..ee77706603c0 100644 > --- a/kernel/sched/topology.c > +++ b/kernel/sched/topology.c > @@ -2067,6 +2067,37 @@ int sched_numa_find_closest(const struct cpumask *cpus, int cpu) > return found; > } > > +/** > + * sched_numa_hop_mask() - Get the cpumask of CPUs at most @hops hops away. > + * @node: The node to count hops from. > + * @hops: Include CPUs up to that many hops away. 0 means local node. > + * > + * Requires rcu_lock to be held. Returned cpumask is only valid within that > + * read-side section, copy it if required beyond that. > + * > + * Note that not all hops are equal in distance; see sched_init_numa() for how > + * distances and masks are handled. > + * > + * Also note that this is a reflection of sched_domains_numa_masks, which may change > + * during the lifetime of the system (offline nodes are taken out of the masks). > + */ > +const struct cpumask *sched_numa_hop_mask(int node, int hops) > +{ > + struct cpumask ***masks = rcu_dereference(sched_domains_numa_masks); > + > + if (node == NUMA_NO_NODE && !hops) > + return cpu_online_mask; > + > + if (node >= nr_node_ids || hops >= sched_domains_numa_levels) > + return ERR_PTR(-EINVAL); This looks like a sanity check. If so, it should go before the snippet above, so that client code would behave consistently. > + > + if (!masks) > + return NULL; In (node == NUMA_NO_NODE && !hops) case you return online cpus. Here you return NULL just to convert it to cpu_online_mask in the caller. This looks inconsistent. So, together with the above comment, this makes me feel that you'd do it like this: const struct cpumask *sched_numa_hop_mask(int node, int hops) { struct cpumask ***masks; if (node >= nr_node_ids || hops >= sched_domains_numa_levels) { #ifdef CONFIG_SCHED_DEBUG pr_err(...); #endif return ERR_PTR(-EINVAL); } if (node == NUMA_NO_NODE && !hops) return cpu_online_mask; /* or NULL */ masks = rcu_dereference(sched_domains_numa_masks); if (!masks) return cpu_online_mask; /* or NULL */ return masks[hops][node]; }