From patchwork Fri Sep 23 15:55:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Schneider X-Patchwork-Id: 12986724 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 C0EEBECAAD8 for ; Fri, 23 Sep 2022 15:56:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232180AbiIWP4f (ORCPT ); Fri, 23 Sep 2022 11:56:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232550AbiIWP4T (ORCPT ); Fri, 23 Sep 2022 11:56:19 -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 C638D147693 for ; Fri, 23 Sep 2022 08:56:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663948569; 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=+vdqLCntBqaxf8FADpHkJLlOi77ldZqexu1XSAK/G7U=; b=Nqix3/gqX6Den5SbB7mbrnYbYd3jhwGksXezS92QMiXcRDBxCPBbqqjt5lRphWeTEPfxW6 HFB6ysQrKP0FT683sIxzYzlNWwtNS1g63pIJ9aroroY5PsHHR2j4/rd5Oegcc+/gqAR/uZ qpVE4+Scmk6fyGtP3mGIzLEbK83V1K8= 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-301-O1NOXulyPgmpNlfzVP4J6g-1; Fri, 23 Sep 2022 11:56:07 -0400 X-MC-Unique: O1NOXulyPgmpNlfzVP4J6g-1 Received: by mail-wm1-f70.google.com with SMTP id b5-20020a05600c4e0500b003b499f99aceso2921749wmq.1 for ; Fri, 23 Sep 2022 08:56:07 -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 :subject:date; bh=+vdqLCntBqaxf8FADpHkJLlOi77ldZqexu1XSAK/G7U=; b=lCt7bm6d9CbyHMPW8I6HQJlM9TAkwaDoTsHWkA1wFoZ1KLeK+sM7RbWkA9tkgXpsUw jCeiSMsPKBlakUyIn1UU/JAurdxfuCRG5L24qwIKx8WaHj2191vtZ3mo4I+DZmURA5sL IHIAYALRDv7cbk8OnX38q102RVk4OM8C6QGTMNJfL/7taC/RuE1OLgXnSK+hckZ3x4dF YlIQek67INNVYvRdcwqp+ILdNZl3J4kygy0tgHRWV5GPKxnIi+yNDwXNSBiXT1HXLvq+ ErS5A//grJ8JyKQfQEyBZkybw3MgARA/9sxq4ow/U5jJbcXgxNWlnfK0jUcAmR1gv1sZ rFwA== X-Gm-Message-State: ACrzQf0iJb5pr+7KHIDkcKSTFq5BIy8xzmi058+lJxr2J4vLdQnVXpKq 4o3VxMy1HzD44gP+2M1xlyaQxV4yrkJgpz+1sqclrv48l1UccwZw4qf7ms8nyKHqf1EZhPEpQmk PlkIiUOPy4NdRBtcJ1FJxdA== X-Received: by 2002:a7b:c457:0:b0:3b4:689d:b408 with SMTP id l23-20020a7bc457000000b003b4689db408mr13584478wmi.22.1663948566652; Fri, 23 Sep 2022 08:56:06 -0700 (PDT) X-Google-Smtp-Source: AMsMyM7tQjllyoAjaE0hgO29ZvO5RUX4Pw8HfukZFiwY7GUlODEt13p9thEkh19Yx2eyohjKDv4MTg== X-Received: by 2002:a7b:c457:0:b0:3b4:689d:b408 with SMTP id l23-20020a7bc457000000b003b4689db408mr13584449wmi.22.1663948566427; Fri, 23 Sep 2022 08:56:06 -0700 (PDT) Received: from vschneid.remote.csb ([185.11.37.247]) by smtp.gmail.com with ESMTPSA id i7-20020a5d5587000000b0021badf3cb26sm9055429wrv.63.2022.09.23.08.56.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Sep 2022 08:56:05 -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 , Heiko Carstens , Tony Luck , Jonathan Cameron , Gal Pressman , Tariq Toukan , Jesse Brandeburg Subject: [PATCH v4 6/7] sched/topology: Introduce for_each_numa_hop_cpu() Date: Fri, 23 Sep 2022 16:55:41 +0100 Message-Id: <20220923155542.1212814-5-vschneid@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220923132527.1001870-1-vschneid@redhat.com> References: <20220923132527.1001870-1-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 3e91ae6d0ad5..7aa7e6a4c739 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -257,5 +257,42 @@ 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 */