From patchwork Thu Mar 30 22:43:40 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Dai X-Patchwork-Id: 668782 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 64D73C77B6D for ; Thu, 30 Mar 2023 22:45:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231250AbjC3WpA (ORCPT ); Thu, 30 Mar 2023 18:45:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230509AbjC3Wod (ORCPT ); Thu, 30 Mar 2023 18:44:33 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 53DD811E9E for ; Thu, 30 Mar 2023 15:44:29 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5463f2d3223so28669887b3.14 for ; Thu, 30 Mar 2023 15:44:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680216269; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=mcnJNCHDCGQ7Pzom/y/MQEMC0VEcznZRpNuHkAP16dM=; b=h+fWFQgFgIewRQ/oEBbhup3NdEkI7VTVNsuOE+DEbbkPezfcqmPxt821KjIEBRuQbG l0zjD5y2da69givEVl5sGT/LrKzZ3TjBHss675g7X6otDgYpfdh+qN2+RTa4QLDKNv9g PDcFoEuUC2taY6ePkBcT1Z7N0RA9q3bwXricL/gDzEv4dXafQDmGXlIKBeyXeR2sEz8o E9FH3ufwR/fPbEciGQgLYG6zQkSaBSw0BtOfmnkR4YfxaB7/7EETD5gleyNZwM9ywyrO n+i0UKoKt4E+CXqxkN8hBn0e4jSHrCNiFCw+gjvKmBdlUar6F84Pyzh3o9haY+aKhz2B Wi9w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680216269; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=mcnJNCHDCGQ7Pzom/y/MQEMC0VEcznZRpNuHkAP16dM=; b=R5Z9o+96WCgj2trDRVLp/Z0P5WABwdgDo66fLFFMemn2XsGIIvpYOVktn+BPOudSnZ YAe0ciTzOvmeK1V6gcaORvk5F0ul0AibAhIbgUArO0AJe36sOZAjtfRgxWzk+6yvp/ke KsghAT+kv0Af+QAWJezObEVmsqKEyCmWvmCWYj/t4Q8Dmd3cyRnIY2+ZM9Ct7QsYc7Ap oXxyV3IzlL3D4qSDo/yO80GzcNOB8hqnr/MFN3PC+AQMpXvnM+kW4r96bPKO1Z/2ZX26 XcnPBp70F6G/504I0doVPupDFaYNdYq8Ce3S6bzHzzjb/nqbYlf5XDM1VSV7lSN9HQoN Y29Q== X-Gm-Message-State: AAQBX9e1XXivlNFPO8HvqASjAUbfLF1z84w7DhkdER/n/iL+viWhEsX6 l7XAuv3+dUhCGyv+EGy26htOlqOCfmHj X-Google-Smtp-Source: AKy350bH+FT4rO63l4r7xqHnuPynxVbMsgCzCxhntsgRkI9CjhoZf4Ra9qEtMvcWq32MGU3qdNWQmk0U4T9r X-Received: from davidai2.mtv.corp.google.com ([2620:15c:211:201:c162:24e8:ec5e:d520]) (user=davidai job=sendgmr) by 2002:a25:c58f:0:b0:b7d:87f:ce3e with SMTP id v137-20020a25c58f000000b00b7d087fce3emr8231840ybe.6.1680216269063; Thu, 30 Mar 2023 15:44:29 -0700 (PDT) Date: Thu, 30 Mar 2023 15:43:40 -0700 In-Reply-To: <20230330224348.1006691-1-davidai@google.com> Mime-Version: 1.0 References: <20230330224348.1006691-1-davidai@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog Message-ID: <20230330224348.1006691-6-davidai@google.com> Subject: [RFC PATCH 5/6] dt-bindings: cpufreq: add bindings for virtual kvm cpufreq From: David Dai To: "Rafael J. Wysocki" , Viresh Kumar , Rob Herring , Krzysztof Kozlowski , David Dai Cc: Saravana Kannan , kernel-team@android.com, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Add devicetree bindings for a virtual kvm cpufreq driver. Co-developed-by: Saravana Kannan Signed-off-by: Saravana Kannan Signed-off-by: David Dai --- .../bindings/cpufreq/cpufreq-virtual-kvm.yaml | 39 +++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 Documentation/devicetree/bindings/cpufreq/cpufreq-virtual-kvm.yaml diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-virtual-kvm.yaml b/Documentation/devicetree/bindings/cpufreq/cpufreq-virtual-kvm.yaml new file mode 100644 index 000000000000..31e64558a7f1 --- /dev/null +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-virtual-kvm.yaml @@ -0,0 +1,39 @@ +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/cpufreq/cpufreq-virtual-kvm.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Virtual KVM CPUFreq + +maintainers: + - David Dai + +description: | + + KVM CPUFreq is a virtualized driver in guest kernels that sends utilization + of its vCPUs as a hint to the host. The host uses hint to schedule vCPU + threads and select CPU frequency. It enables accurate Per-Entity Load + Tracking for tasks running in the guest by querying host CPU frequency + unless a virtualized FIE exists(Like AMUs). + +properties: + compatible: + const: virtual,kvm-cpufreq + +required: + - compatible + +additionalProperties: false + +examples: + - | + { + #address-cells = <2>; + #size-cells = <2>; + + cpufreq { + compatible = "virtual,kvm-cpufreq"; + }; + + }; From patchwork Thu Mar 30 22:43:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Dai X-Patchwork-Id: 669586 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 D2CCCC7619A for ; Thu, 30 Mar 2023 22:45:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231179AbjC3WpP (ORCPT ); Thu, 30 Mar 2023 18:45:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230250AbjC3Wok (ORCPT ); Thu, 30 Mar 2023 18:44:40 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0EE6113FB for ; Thu, 30 Mar 2023 15:44:34 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id b124-20020a253482000000b00b72947f6a54so20285662yba.14 for ; Thu, 30 Mar 2023 15:44:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680216274; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=PafzZUjsN+AldhPHNYx1ZKiIIku0MB5EoRgnFO5S24A=; b=IKo+uYXFFOMVUkZCYD9QMyvEzy1K5F2Pc9DdKpm5zjml0/VAGJUaLqqMWkx5eqevIY dFPCOU0wSNRnXquMJxQGOpdJihyAhn9Wqz/DZRA8h8eZZlflCfxVOo0BLAZxHkF6KQno ODtLcGtCtxingBlMnCwD+pBF0PySDATkGjxGl5tf6QtSVZDGX/yjLbR/rPR3GEgGA8L4 ENcw1nZtvF2tW2qjsprDMsEIrbTGDXrU1qEcikQoszEXgxUXOxY8fqPN8rBKcF8L9Zld n4jp4Mx0M90/W/506LqL6MYLmvBH25YiUD8PRR8t0m/lQpg06cHUDmRR9aUCuuiQjCVV QVXQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680216274; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=PafzZUjsN+AldhPHNYx1ZKiIIku0MB5EoRgnFO5S24A=; b=jWkrUEoHgY3J8uLdf0SmmZc68iGRp4qbSpm+nTXY5LVAWo6CaOglQp/Jq1c+lQi9NY ogtEeilveBztuff1S05qP4BxClwQOSL0i/3Hi2eps90NJLyrh2YF56G4QEraqGoCUpD9 VNO8LLNtnvrvXvWhKAQWjjD0WYUBtDWWpIJ1R/2xM889wp5PkOP2PIHKFk9jVv2mpiI3 CkOJl0kA2y3Hdngh8hYXqQlL7tgba6CKIkLJpRdzVovCFCB2Chb8i7Lp/j0FIV+ZUnt7 2f+NOVM9qQduWZrRzHfz6efwppognpE84S/Pl0Nbmx//2Nh79Ewb8cw90gNkRq2LgW7a ZqUg== X-Gm-Message-State: AAQBX9eRbpE/kTSrW7d/Wpc2RZphFRe15FnMLIgU8rjzDGGBGwjnII75 FQ7g3SUVPp9DeAH7h167UeUX5frE2AFO X-Google-Smtp-Source: AKy350YE+XR9BlmvWUfrlL4ZhH75skUxtvf6Y6Jcl33IrYOudgql0YBgTSgHkhTSUkWj1dRNbRJzCn45A6sz X-Received: from davidai2.mtv.corp.google.com ([2620:15c:211:201:c162:24e8:ec5e:d520]) (user=davidai job=sendgmr) by 2002:a81:ad05:0:b0:545:fff5:b639 with SMTP id l5-20020a81ad05000000b00545fff5b639mr7392338ywh.1.1680216273889; Thu, 30 Mar 2023 15:44:33 -0700 (PDT) Date: Thu, 30 Mar 2023 15:43:41 -0700 In-Reply-To: <20230330224348.1006691-1-davidai@google.com> Mime-Version: 1.0 References: <20230330224348.1006691-1-davidai@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog Message-ID: <20230330224348.1006691-7-davidai@google.com> Subject: [RFC PATCH 6/6] cpufreq: add kvm-cpufreq driver From: David Dai To: "Rafael J. Wysocki" , Viresh Kumar , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider Cc: David Dai , Saravana Kannan , kernel-team@android.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Introduce a virtualized cpufreq driver for guest kernels to improve performance and power of workloads within VMs. This driver does two main things: 1. Sends utilization of vCPUs as a hint to the host. The host uses the hint to schedule the vCPU threads and decide physical CPU frequency. 2. If a VM does not support a virtualized FIE(like AMUs), it uses hypercalls to update the guest's frequency scaling factor periodically by querying the host CPU frequency. This enables accurate Per-Entity Load Tracking for tasks running in the guest. Note that because the host already employs a rate_limit_us, we set the transition_delay_us of the cpufreq policy to a miniscule value(1) to avoid any additional delays between when the runqueue's util change and a frequency response on the host. Co-developed-by: Saravana Kannan Signed-off-by: Saravana Kannan Signed-off-by: David Dai --- drivers/cpufreq/Kconfig | 13 ++ drivers/cpufreq/Makefile | 1 + drivers/cpufreq/kvm-cpufreq.c | 245 ++++++++++++++++++++++++++++++++++ include/linux/sched.h | 1 + kernel/sched/core.c | 6 + 5 files changed, 266 insertions(+) create mode 100644 drivers/cpufreq/kvm-cpufreq.c diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig index 2c839bd2b051..0ef9d5be7c4d 100644 --- a/drivers/cpufreq/Kconfig +++ b/drivers/cpufreq/Kconfig @@ -217,6 +217,19 @@ config CPUFREQ_DT If in doubt, say N. +config CPUFREQ_KVM + tristate "KVM cpufreq driver" + help + This adds a virtualized KVM cpufreq driver for guest kernels that + uses hypercalls to communicate with the host. It sends utilization + updates to the host and gets used to schedule vCPU threads and + select CPU frequency. If a VM does not support a virtualized FIE + such as AMUs, it updates the frequency scaling factor by polling + host CPU frequency to enable accurate Per-Entity Load Tracking + for tasks running in the guest. + + If in doubt, say N. + config CPUFREQ_DT_PLATDEV bool help diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile index ef8510774913..179ea8d45135 100644 --- a/drivers/cpufreq/Makefile +++ b/drivers/cpufreq/Makefile @@ -16,6 +16,7 @@ obj-$(CONFIG_CPU_FREQ_GOV_ATTR_SET) += cpufreq_governor_attr_set.o obj-$(CONFIG_CPUFREQ_DT) += cpufreq-dt.o obj-$(CONFIG_CPUFREQ_DT_PLATDEV) += cpufreq-dt-platdev.o +obj-$(CONFIG_CPUFREQ_KVM) += kvm-cpufreq.o # Traces CFLAGS_amd-pstate-trace.o := -I$(src) diff --git a/drivers/cpufreq/kvm-cpufreq.c b/drivers/cpufreq/kvm-cpufreq.c new file mode 100644 index 000000000000..1542c9ac4119 --- /dev/null +++ b/drivers/cpufreq/kvm-cpufreq.c @@ -0,0 +1,245 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2023 Google LLC + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static void kvm_scale_freq_tick(void) +{ + unsigned long scale, cur_freq, max_freq; + struct arm_smccc_res hvc_res; + + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_GET_CUR_CPUFREQ_FUNC_ID, + 0, &hvc_res); + + cur_freq = hvc_res.a0; + max_freq = cpufreq_get_hw_max_freq(task_cpu(current)); + scale = (cur_freq << SCHED_CAPACITY_SHIFT) / max_freq; + + this_cpu_write(arch_freq_scale, (unsigned long)scale); +} + +static struct scale_freq_data kvm_sfd = { + .source = SCALE_FREQ_SOURCE_ARCH, + .set_freq_scale = kvm_scale_freq_tick, +}; + +struct remote_data { + int ret; + struct cpufreq_frequency_table *table; +}; + +static void remote_get_freqtbl_num_entries(void *data) +{ + struct arm_smccc_res hvc_res; + u32 freq = 1UL; + int *idx = data; + + while (freq != CPUFREQ_TABLE_END) { + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_GET_CPUFREQ_TBL_FUNC_ID, + *idx, &hvc_res); + if (hvc_res.a0) { + *idx = -ENODEV; + return; + } + freq = hvc_res.a1; + (*idx)++; + } +} + +static int kvm_cpufreq_get_freqtbl_num_entries(int cpu) +{ + int num_entries = 0; + + smp_call_function_single(cpu, remote_get_freqtbl_num_entries, &num_entries, true); + return num_entries; +} + +static void remote_populate_freqtbl(void *data) +{ + struct arm_smccc_res hvc_res; + struct remote_data *freq_data = data; + struct cpufreq_frequency_table *pos; + struct cpufreq_frequency_table *table = freq_data->table; + int idx; + + cpufreq_for_each_entry_idx(pos, table, idx) { + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_GET_CPUFREQ_TBL_FUNC_ID, + idx, &hvc_res); + if (hvc_res.a0) { + freq_data->ret = -ENODEV; + return; + } + pos->frequency = hvc_res.a1; + } + freq_data->ret = 0; +} + +static int kvm_cpufreq_populate_freqtbl(struct cpufreq_frequency_table *table, int cpu) +{ + struct remote_data freq_data; + + freq_data.table = table; + smp_call_function_single(cpu, remote_populate_freqtbl, &freq_data, true); + return freq_data.ret; +} + +static unsigned int kvm_cpufreq_setutil_hyp(struct cpufreq_policy *policy) +{ + struct arm_smccc_res hvc_res; + u32 util = sched_cpu_util_freq(policy->cpu); + u32 cap = arch_scale_cpu_capacity(policy->cpu); + u32 threshold = cap - (cap >> 2); + + if (util > threshold) + util = (cap + threshold) >> 1; + + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_UTIL_HINT_FUNC_ID, + util, &hvc_res); + + return hvc_res.a0; +} + +static unsigned int kvm_cpufreq_fast_switch(struct cpufreq_policy *policy, + unsigned int target_freq) +{ + kvm_cpufreq_setutil_hyp(policy); + return target_freq; +} + +static int kvm_cpufreq_target_index(struct cpufreq_policy *policy, + unsigned int index) +{ + return kvm_cpufreq_setutil_hyp(policy); +} + +static const struct of_device_id kvm_cpufreq_match[] = { + { .compatible = "virtual,kvm-cpufreq"}, + {} +}; +MODULE_DEVICE_TABLE(of, kvm_cpufreq_match); + +static int kvm_cpufreq_cpu_init(struct cpufreq_policy *policy) +{ + struct device *cpu_dev; + struct cpufreq_frequency_table *table; + int num_entries; + + cpu_dev = get_cpu_device(policy->cpu); + if (!cpu_dev) { + pr_err("%s: failed to get cpu%d device\n", __func__, + policy->cpu); + return -ENODEV; + } + + num_entries = kvm_cpufreq_get_freqtbl_num_entries(policy->cpu); + if (num_entries == -ENODEV) + return -ENODEV; + + table = kcalloc(num_entries, sizeof(*table), GFP_KERNEL); + if (!table) + return -ENOMEM; + + table[num_entries-1].frequency = CPUFREQ_TABLE_END; + + if (kvm_cpufreq_populate_freqtbl(table, policy->cpu)) + return -ENODEV; + + policy->freq_table = table; + policy->dvfs_possible_from_any_cpu = false; + policy->fast_switch_possible = true; + policy->transition_delay_us = 1; + + /* + * Only takes effect if another FIE source such as AMUs + * have not been registered. + */ + topology_set_scale_freq_source(&kvm_sfd, policy->cpus); + + return 0; +} + +static int kvm_cpufreq_cpu_exit(struct cpufreq_policy *policy) +{ + kfree(policy->freq_table); + return 0; +} + +static int kvm_cpufreq_online(struct cpufreq_policy *policy) +{ + /* Nothing to restore. */ + return 0; +} + +static int kvm_cpufreq_offline(struct cpufreq_policy *policy) +{ + /* Dummy offline() to avoid exit() being called and freeing resources. */ + return 0; +} + +static struct cpufreq_driver cpufreq_kvm_driver = { + .name = "kvm-cpufreq", + .init = kvm_cpufreq_cpu_init, + .exit = kvm_cpufreq_cpu_exit, + .online = kvm_cpufreq_online, + .offline = kvm_cpufreq_offline, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = kvm_cpufreq_target_index, + .fast_switch = kvm_cpufreq_fast_switch, + .attr = cpufreq_generic_attr, +}; + +static int kvm_cpufreq_driver_probe(struct platform_device *pdev) +{ + int ret; + + ret = cpufreq_register_driver(&cpufreq_kvm_driver); + if (ret) { + dev_err(&pdev->dev, "KVM CPUFreq driver failed to register: %d\n", ret); + return ret; + } + + dev_dbg(&pdev->dev, "KVM CPUFreq driver initialized\n"); + return 0; +} + +static int kvm_cpufreq_driver_remove(struct platform_device *pdev) +{ + cpufreq_unregister_driver(&cpufreq_kvm_driver); + return 0; +} + +static struct platform_driver kvm_cpufreq_driver = { + .probe = kvm_cpufreq_driver_probe, + .remove = kvm_cpufreq_driver_remove, + .driver = { + .name = "kvm-cpufreq", + .of_match_table = kvm_cpufreq_match, + }, +}; + +static int __init kvm_cpufreq_init(void) +{ + return platform_driver_register(&kvm_cpufreq_driver); +} +postcore_initcall(kvm_cpufreq_init); + +static void __exit kvm_cpufreq_exit(void) +{ + platform_driver_unregister(&kvm_cpufreq_driver); +} +module_exit(kvm_cpufreq_exit); + +MODULE_DESCRIPTION("KVM cpufreq driver"); +MODULE_LICENSE("GPL"); diff --git a/include/linux/sched.h b/include/linux/sched.h index d8c346fcdf52..bd38aa32a57c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2303,6 +2303,7 @@ static inline bool owner_on_cpu(struct task_struct *owner) /* Returns effective CPU energy utilization, as seen by the scheduler */ unsigned long sched_cpu_util(int cpu); +unsigned long sched_cpu_util_freq(int cpu); #endif /* CONFIG_SMP */ #ifdef CONFIG_RSEQ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7700ef5610c1..dd46f4cc629b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7421,6 +7421,12 @@ unsigned long sched_cpu_util(int cpu) { return effective_cpu_util(cpu, cpu_util_cfs(cpu), ENERGY_UTIL, NULL); } + +unsigned long sched_cpu_util_freq(int cpu) +{ + return effective_cpu_util(cpu, cpu_util_cfs(cpu), FREQUENCY_UTIL, NULL); +} + #endif /* CONFIG_SMP */ /**