From nobody Sat Apr 11 03:55:19 2026 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 B5D53C25B0E for ; Tue, 16 Aug 2022 18:08:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237020AbiHPSIj (ORCPT ); Tue, 16 Aug 2022 14:08:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236965AbiHPSHz (ORCPT ); Tue, 16 Aug 2022 14:07:55 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9630C85AAD for ; Tue, 16 Aug 2022 11:07:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1660673265; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ygl4bsiGppbXjaR+QFxwzenbyEWvTTquS8G3MYyuF5k=; b=feuPUzCzSSIW0VEOdyBD5hBkbKU5K8dZ2PYitRqgcA7CNZZFQCAkSDry4saLUk/Zsa5BAn 4Ivu011wKRP/+5AtsCRIjgyyHDq0GYwy5lweBNxlzKsgxT90y0ACXjivG8eA7Na0/IkJml 5fihCaXOVTE4CZ6ZsvyAHKf/AdpMjwg= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-371-yl8Lui23OHSqTa3N935NeQ-1; Tue, 16 Aug 2022 14:07:44 -0400 X-MC-Unique: yl8Lui23OHSqTa3N935NeQ-1 Received: by mail-wm1-f70.google.com with SMTP id h62-20020a1c2141000000b003a4f57eaeaaso5216610wmh.8 for ; Tue, 16 Aug 2022 11:07:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=Ygl4bsiGppbXjaR+QFxwzenbyEWvTTquS8G3MYyuF5k=; b=G8gmgSLKjRIiafDEiJg70yyGlP0sqS+aQ7KMrUUjPc2CLhbdAsowNU4NHY4oTNsSQ4 Us8PA/0xaF9pIy6HWWDVG93YOG7JqPCj+AZtps6L92AgkOubOK3LLDlBpeHEEIL9lmdX aTOxi/a/OVT2EJqopnihFEcLn5cZnbGgmi7IhPJY6JtK1grH5Fgofd6PLe7uCunoGeTR dwTFFeAxLWrkjOUaLB+H4j198Hrpzn+6dPGUWGyJ2hmYa+Iw9Pnxj9NDSsZffvTNVT0U ROQv/3vjgpUB+D55zBVL7/o18eiwIdqRKsBRsvGNzJgbZf74Pn9NU2epk/M8NuuL6vY9 g8Ag== X-Gm-Message-State: ACgBeo08Cxirza6M0g61u+rhRLQL/dBTm9iuA+QXp7dVN2qZDRfsq9TD ukl/vr+wm2KPe6Cr8b//Zc+hTLl6QyEQwQ1h7xOM649zAr6pbcc+SO8QlX8bpSGz94xwc21pT3G x+DMFNfuaaIz0ioUwSxTh428w X-Received: by 2002:a05:600c:3ac9:b0:3a5:f114:1f8 with SMTP id d9-20020a05600c3ac900b003a5f11401f8mr7308789wms.204.1660673262253; Tue, 16 Aug 2022 11:07:42 -0700 (PDT) X-Google-Smtp-Source: AA6agR48CFk/soei7QbfayAzQBKnIM/T9VknX41x2JuU6hM+hzmZxgjXWFEqwx3WheqBotPeya0UKg== X-Received: by 2002:a05:600c:3ac9:b0:3a5:f114:1f8 with SMTP id d9-20020a05600c3ac900b003a5f11401f8mr7308780wms.204.1660673262069; Tue, 16 Aug 2022 11:07:42 -0700 (PDT) Received: from vschneid.remote.csb ([185.11.37.247]) by smtp.gmail.com with ESMTPSA id o8-20020a05600c4fc800b003a319bd3278sm14694961wmq.40.2022.08.16.11.07.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Aug 2022 11:07:41 -0700 (PDT) From: Valentin Schneider To: netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Saeed Mahameed , Leon Romanovsky , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Yury Norov , Andy Shevchenko , Rasmus Villemoes , Ingo Molnar , Peter Zijlstra , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Mel Gorman , Greg Kroah-Hartman , Barry Song , Heiko Carstens , Tony Luck , Jonathan Cameron , Gal Pressman , Tariq Toukan Subject: [PATCH 4/5] sched/topology: Introduce for_each_numa_hop_cpu() Date: Tue, 16 Aug 2022 19:07:26 +0100 Message-Id: <20220816180727.387807-5-vschneid@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220816180727.387807-1-vschneid@redhat.com> References: <20220816180727.387807-1-vschneid@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The recently introduced sched_numa_hop_mask() exposes cpumasks of CPUs reachable within a given distance budget, but this means each successive cpumask is a superset of the previous one. Code wanting to allocate one item per CPU (e.g. IRQs) at increasing distances would thus need to allocate a temporary cpumask to note which CPUs have already been visited. This can be prevented by leveraging for_each_cpu_andnot() - package all that logic into one ugl^D fancy macro. Signed-off-by: Valentin Schneider --- include/linux/topology.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/include/linux/topology.h b/include/linux/topology.h index 13b82b83e547..6c671dc3252c 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -254,5 +254,42 @@ static inline const struct cpumask *sched_numa_hop_mas= k(int node, int hops) } #endif /* CONFIG_NUMA */ =20 +/** + * for_each_numa_hop_cpu - iterate over CPUs by increasing NUMA distance, + * starting from a given node. + * @cpu: the iteration variable. + * @node: the NUMA node to start the search from. + * + * Requires rcu_lock to be held. + * Careful: this is a double loop, 'break' won't work as expected. + * + * + * Implementation notes: + * + * Providing it is valid, the mask returned by + * sched_numa_hop_mask(node, hops+1) + * is a superset of the one returned by + * sched_numa_hop_mask(node, hops) + * which may not be that useful for drivers that try to spread things out = and + * want to visit a CPU not more than once. + * + * To accommodate for that, we use for_each_cpu_andnot() to iterate over t= he cpus + * of sched_numa_hop_mask(node, hops+1) with the CPUs of + * sched_numa_hop_mask(node, hops) removed, IOW we only iterate over CPUs + * a given distance away (rather than *up to* a given distance). + * + * hops=3D0 forces us to play silly games: we pass cpu_none_mask to + * for_each_cpu_andnot(), which turns it into for_each_cpu(). + */ +#define for_each_numa_hop_cpu(cpu, node) \ + for (struct { const struct cpumask *curr, *prev; int hops; } __v =3D \ + { sched_numa_hop_mask(node, 0), NULL, 0 }; \ + !IS_ERR_OR_NULL(__v.curr); \ + __v.hops++, \ + __v.prev =3D __v.curr, \ + __v.curr =3D sched_numa_hop_mask(node, __v.hops)) \ + for_each_cpu_andnot(cpu, \ + __v.curr, \ + __v.hops ? __v.prev : cpu_none_mask) =20 #endif /* _LINUX_TOPOLOGY_H */ --=20 2.31.1