From patchwork Tue Aug 16 18:07:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Schneider X-Patchwork-Id: 12945182 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 AA48BC2BB41 for ; Tue, 16 Aug 2022 18:08:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236916AbiHPSIX (ORCPT ); Tue, 16 Aug 2022 14:08:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38324 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236941AbiHPSHz (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 0F87C85FE0 for ; Tue, 16 Aug 2022 11:07:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1660673264; 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=J2EZDDOzoQmAGaAOY2K/XyZ904+hprlQYeJVL2Rzf2lYBDktnGRqr225XJNn8rWlS8WikF hC7MgZWnTtA1eUSRGq1PDE03pTzZJoZSghlqT96F/+eFHYnSG5bA4WH/004mw59xjNNvdK v2FIpXGYDe6VFQBEcEKXTcoA8MbreIU= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-625-C3Xrr2QEOCGnI68WGeJppA-1; Tue, 16 Aug 2022 14:07:43 -0400 X-MC-Unique: C3Xrr2QEOCGnI68WGeJppA-1 Received: by mail-wm1-f71.google.com with SMTP id z16-20020a05600c0a1000b003a5c18a66f0so5222977wmp.6 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=mbcjaTNy9G+HqKX51Do97UyFXZBSea3DVg53RdON4X6dF2DnREKxLS7FyACAFs8ijM n9Ay8LCDifzKFAEpROguxOO4NgGJtOZEq1UtD4gpgoTTwNHEYDaVrktvKBXvNly4Gjj8 hznMEfZv2zM+kVrn3wOQZ4W55ngh+5TIe6aDlpwGC1NTdeB+ocX0wPEk1cMhd6Ye00yB y/tDi8tUqWR6UBEtJWAax7gNBd6UwM2JpQqFpJxEbiq3YP4AyGxrfiQ3LXGc9EPzpIcU KZEHZINCodLXjsN70CaHVzhw7T29ERNizbu/4C/km2VtbzSZGpybV9UcYZugwltBJifd OFVg== X-Gm-Message-State: ACgBeo1QnToPY+5aX58X8sw7t8N5Q8vyZvg7oG3AjrVT8QCeQSzP5iOb BB54FHzwZxr2HiGQgChEmmGMMxt2JUdo5YTBsSeL2suhGEz7BBUVZPZnLyaK6nquErtx6WKPlME pEypCdel99KEpRm69fvWlRg== X-Received: by 2002:a05:600c:3ac9:b0:3a5:f114:1f8 with SMTP id d9-20020a05600c3ac900b003a5f11401f8mr7308799wms.204.1660673262254; 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 Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org 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_mask(int node, int hops) } #endif /* CONFIG_NUMA */ +/** + * 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 the 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=0 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 = \ + { sched_numa_hop_mask(node, 0), NULL, 0 }; \ + !IS_ERR_OR_NULL(__v.curr); \ + __v.hops++, \ + __v.prev = __v.curr, \ + __v.curr = sched_numa_hop_mask(node, __v.hops)) \ + for_each_cpu_andnot(cpu, \ + __v.curr, \ + __v.hops ? __v.prev : cpu_none_mask) #endif /* _LINUX_TOPOLOGY_H */