From patchwork Thu Oct 20 21:59:59 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tim Chen X-Patchwork-Id: 9387663 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9A74E607D0 for ; Thu, 20 Oct 2016 22:02:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7A3A729CAF for ; Thu, 20 Oct 2016 22:02:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6CC3F29CBA; Thu, 20 Oct 2016 22:02:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 946D229CB2 for ; Thu, 20 Oct 2016 22:02:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933059AbcJTWBE (ORCPT ); Thu, 20 Oct 2016 18:01:04 -0400 Received: from mga03.intel.com ([134.134.136.65]:58664 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757188AbcJTWBA (ORCPT ); Thu, 20 Oct 2016 18:01:00 -0400 Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga103.jf.intel.com with ESMTP; 20 Oct 2016 15:00:59 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,521,1473145200"; d="scan'208";a="21915335" Received: from skl-02.jf.intel.com ([10.23.236.208]) by fmsmga005.fm.intel.com with ESMTP; 20 Oct 2016 15:00:58 -0700 From: Tim Chen To: rjw@rjwysocki.net, tglx@linutronix.de, mingo@redhat.com, bp@suse.de Cc: Tim Chen , x86@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, peterz@infradead.org, jolsa@redhat.com, Srinivas Pandruvada Subject: [PATCH v6 5/9] x86/sysctl: Add sysctl for ITMT scheduling feature Date: Thu, 20 Oct 2016 14:59:59 -0700 Message-Id: X-Mailer: git-send-email 2.5.5 In-Reply-To: References: In-Reply-To: References: Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Intel Turbo Boost Max Technology 3.0 (ITMT) feature allows some cores to be boosted to higher turbo frequency than others. Add /proc/sys/kernel/sched_itmt_enabled so operator can enable/disable scheduling of tasks that favor cores with higher turbo boost frequency potential. By default, system that is ITMT capable and single socket has this feature turned on. It is more likely to be lightly loaded and operates in Turbo range. When there is a change in the ITMT scheduling operation desired, a rebuild of the sched domain is initiated so the scheduler can set up sched domains with appropriate flag to enable/disable ITMT scheduling operations. Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Srinivas Pandruvada --- arch/x86/include/asm/topology.h | 7 ++- arch/x86/kernel/itmt.c | 110 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 114 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index a73fb80..46ebdd1 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -155,23 +155,26 @@ extern bool x86_topology_update; #include DECLARE_PER_CPU_READ_MOSTLY(int, sched_core_priority); +extern unsigned int __read_mostly sysctl_sched_itmt_enabled; /* Interface to set priority of a cpu */ void sched_set_itmt_core_prio(int prio, int core_cpu); /* Interface to notify scheduler that system supports ITMT */ -void sched_set_itmt_support(void); +int sched_set_itmt_support(void); /* Interface to notify scheduler that system revokes ITMT support */ void sched_clear_itmt_support(void); #else /* CONFIG_SCHED_ITMT */ +#define sysctl_sched_itmt_enabled 0 static inline void sched_set_itmt_core_prio(int prio, int core_cpu) { } -static inline void sched_set_itmt_support(void) +static inline int sched_set_itmt_support(void) { + return 0; } static inline void sched_clear_itmt_support(void) { diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c index 63c9b3e..e999e6e 100644 --- a/arch/x86/kernel/itmt.c +++ b/arch/x86/kernel/itmt.c @@ -34,6 +34,67 @@ DEFINE_PER_CPU_READ_MOSTLY(int, sched_core_priority); /* Boolean to track if system has ITMT capabilities */ static bool __read_mostly sched_itmt_capable; +/* + * Boolean to control whether we want to move processes to cpu capable + * of higher turbo frequency for cpus supporting Intel Turbo Boost Max + * Technology 3.0. + * + * It can be set via /proc/sys/kernel/sched_itmt_enabled + */ +unsigned int __read_mostly sysctl_sched_itmt_enabled; + +static int sched_itmt_update_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + int ret; + unsigned int old_sysctl; + + mutex_lock(&itmt_update_mutex); + + if (!sched_itmt_capable) { + mutex_unlock(&itmt_update_mutex); + return -EINVAL; + } + + old_sysctl = sysctl_sched_itmt_enabled; + ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + + if (!ret && write && old_sysctl != sysctl_sched_itmt_enabled) { + x86_topology_update = true; + rebuild_sched_domains(); + } + + mutex_unlock(&itmt_update_mutex); + + return ret; +} + +static unsigned int zero; +static unsigned int one = 1; +static struct ctl_table itmt_kern_table[] = { + { + .procname = "sched_itmt_enabled", + .data = &sysctl_sched_itmt_enabled, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = sched_itmt_update_handler, + .extra1 = &zero, + .extra2 = &one, + }, + {} +}; + +static struct ctl_table itmt_root_table[] = { + { + .procname = "kernel", + .mode = 0555, + .child = itmt_kern_table, + }, + {} +}; + +static struct ctl_table_header *itmt_sysctl_header; + /** * sched_set_itmt_support() - Indicate platform supports ITMT * @@ -45,14 +106,44 @@ static bool __read_mostly sched_itmt_capable; * * This must be done only after sched_set_itmt_core_prio * has been called to set the cpus' priorities. + * It must not be called with cpu hot plug lock + * held as we need to acquire the lock to rebuild sched domains + * later. + * + * Return: 0 on success */ -void sched_set_itmt_support(void) +int sched_set_itmt_support(void) { mutex_lock(&itmt_update_mutex); + if (sched_itmt_capable) { + mutex_unlock(&itmt_update_mutex); + return 0; + } + + itmt_sysctl_header = register_sysctl_table(itmt_root_table); + if (!itmt_sysctl_header) { + mutex_unlock(&itmt_update_mutex); + return -ENOMEM; + } + sched_itmt_capable = true; + /* + * ITMT capability automatically enables ITMT + * scheduling for small systems (single node). + */ + if (topology_num_packages() == 1) + sysctl_sched_itmt_enabled = 1; + + if (sysctl_sched_itmt_enabled) { + x86_topology_update = true; + rebuild_sched_domains(); + } + mutex_unlock(&itmt_update_mutex); + + return 0; } /** @@ -61,13 +152,30 @@ void sched_set_itmt_support(void) * This function is used by the OS to indicate that it has * revoked the platform's support of ITMT feature. * + * It must not be called with cpu hot plug lock + * held as we need to acquire the lock to rebuild sched domains + * later. */ void sched_clear_itmt_support(void) { mutex_lock(&itmt_update_mutex); + if (!sched_itmt_capable) { + mutex_unlock(&itmt_update_mutex); + return; + } sched_itmt_capable = false; + if (itmt_sysctl_header) + unregister_sysctl_table(itmt_sysctl_header); + + if (sysctl_sched_itmt_enabled) { + /* disable sched_itmt if we are no longer ITMT capable */ + sysctl_sched_itmt_enabled = 0; + x86_topology_update = true; + rebuild_sched_domains(); + } + mutex_unlock(&itmt_update_mutex); }