From patchwork Thu Aug 18 16:45:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Schneider X-Patchwork-Id: 12947444 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 C40E7C00140 for ; Thu, 18 Aug 2022 16:45:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344992AbiHRQpr (ORCPT ); Thu, 18 Aug 2022 12:45:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344966AbiHRQpj (ORCPT ); Thu, 18 Aug 2022 12:45:39 -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 F0412BC110 for ; Thu, 18 Aug 2022 09:45:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1660841138; 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=GzcKuUPZqXmCm4F6x1IrPdfv2sF4A2KNLjqwjFkS4pPCRpoUFNsRv/AsOB3VOCJRpRsXLS x2PSCpRbk6S7ODKNI61/6q9ZSz6OJPMvCpqPVlEH69ruxi2sBh5FcgIcbhgkyjJVTEwMeL T4rLWvFPbKDUZOWVp1YYwRyTT+QvXVg= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-437-81fzTA6SOjy4o4tGNb2Ciw-1; Thu, 18 Aug 2022 12:45:37 -0400 X-MC-Unique: 81fzTA6SOjy4o4tGNb2Ciw-1 Received: by mail-wr1-f70.google.com with SMTP id d11-20020adfc08b000000b002207555c1f6so296155wrf.7 for ; Thu, 18 Aug 2022 09:45:36 -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=JYJjJE7rzSGoUfjG5EPpO4r8T2j/gQq96a8XKUdLBvYzzHdIhBjGk8JONlB+pUoHVE sMPTvXIsHioufgdSvhBqZKROl4bSXKTiMdGoCwbHeSosXY4zOmz1b9pmF800CAh+qMNt SGQ7FIJ7dz2BzQNPMpKDAw0Wk8zeS7gOafBkIpEPukLfftrCMCcTO1Ui7CGwQprHzs1q b0lTig463m8hajV0GojFZJH79kFl4WaDM8h2dRxA62t2Fjfah4NzWSgsLhKHr5Vc0gPK CEP4qiFDslbaGX+nKxkRQRfGtfDGACNlBiUUEoSYb5CkCqpHFbYFdl/mK6po7uO4sSux SHRQ== X-Gm-Message-State: ACgBeo0qjWoy31fzrQcx3qssqKvUYd3avlea/F5064eAYcwh8dwYtW2c oG9rPcdLMrdxLZgbyQLu7EEmuWPVBRvdq84WxM44F0DGh5TrFB3jptCEwz+V8taDJTyHpOv29Vk dd49/SyLwNsKwyWMwdO2LzcQG6wTxTtn32NJLHMbVntjMpjz8bDay2YjcJlSvVIFawg2D X-Received: by 2002:a5d:63cb:0:b0:21e:b81d:8b0d with SMTP id c11-20020a5d63cb000000b0021eb81d8b0dmr2101122wrw.526.1660841135402; Thu, 18 Aug 2022 09:45:35 -0700 (PDT) X-Google-Smtp-Source: AA6agR7i0NVijGHDSaLCCQYtUON7K5y9O7pv4DOZf3cy/HYjnD2P0jXlg2O08mjKG+P/oEyOridfcQ== X-Received: by 2002:a5d:63cb:0:b0:21e:b81d:8b0d with SMTP id c11-20020a5d63cb000000b0021eb81d8b0dmr2101084wrw.526.1660841135139; Thu, 18 Aug 2022 09:45:35 -0700 (PDT) Received: from vschneid.remote.csb ([185.11.37.247]) by smtp.gmail.com with ESMTPSA id d7-20020a05600c3ac700b003a5ad7f6de2sm2465458wms.15.2022.08.18.09.45.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Aug 2022 09:45:34 -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 v2 4/5] sched/topology: Introduce for_each_numa_hop_cpu() Date: Thu, 18 Aug 2022 17:45:21 +0100 Message-Id: <20220818164522.1087673-2-vschneid@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220818164522.1087673-1-vschneid@redhat.com> References: <20220817175812.671843-1-vschneid@redhat.com> <20220818164522.1087673-1-vschneid@redhat.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@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 */