From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4614FC433E0 for ; Mon, 1 Jun 2020 09:53:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27D5F2077D for ; Mon, 1 Jun 2020 09:53:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726159AbgFAJwa (ORCPT ); Mon, 1 Jun 2020 05:52:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726066AbgFAJwY (ORCPT ); Mon, 1 Jun 2020 05:52:24 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6D62C08C5C0; Mon, 1 Jun 2020 02:52:23 -0700 (PDT) Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jfh7E-0003f2-Jw; Mon, 01 Jun 2020 11:52:20 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 3CBB31C0244; Mon, 1 Jun 2020 11:52:20 +0200 (CEST) Date: Mon, 01 Jun 2020 09:52:20 -0000 From: "tip-bot2 for Peter Zijlstra" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] smp: Optimize send_call_function_single_ipi() Cc: "Peter Zijlstra (Intel)" , Ingo Molnar , x86 , LKML In-Reply-To: <20200526161907.953304789@infradead.org> References: <20200526161907.953304789@infradead.org> MIME-Version: 1.0 Message-ID: <159100514006.17951.5633093083657745774.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: b2a02fc43a1f40ef4eb2fb2b06357382608d4d84 Gitweb: https://git.kernel.org/tip/b2a02fc43a1f40ef4eb2fb2b06357382608d4d84 Author: Peter Zijlstra AuthorDate: Tue, 26 May 2020 18:11:01 +02:00 Committer: Ingo Molnar CommitterDate: Thu, 28 May 2020 10:54:15 +02:00 smp: Optimize send_call_function_single_ipi() Just like the ttwu_queue_remote() IPI, make use of _TIF_POLLING_NRFLAG to avoid sending IPIs to idle CPUs. [ mingo: Fix UP build bug. ] Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200526161907.953304789@infradead.org --- kernel/sched/core.c | 10 ++++++++++ kernel/sched/idle.c | 5 +++++ kernel/sched/sched.h | 7 ++++--- kernel/smp.c | 16 +++++++++++++++- 4 files changed, 34 insertions(+), 4 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2cacc1e..fa0d499 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2296,6 +2296,16 @@ static void wake_csd_func(void *info) sched_ttwu_pending(); } +void send_call_function_single_ipi(int cpu) +{ + struct rq *rq = cpu_rq(cpu); + + if (!set_nr_if_polling(rq->idle)) + arch_send_call_function_single_ipi(cpu); + else + trace_sched_wake_idle_without_ipi(cpu); +} + /* * Queue a task on the target CPUs wake_list and wake the CPU via IPI if * necessary. The wakee CPU on receipt of the IPI will queue the task diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index b743bf3..387fd75 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -289,6 +289,11 @@ static void do_idle(void) */ smp_mb__after_atomic(); + /* + * RCU relies on this call to be done outside of an RCU read-side + * critical section. + */ + flush_smp_call_function_from_idle(); sched_ttwu_pending(); schedule_idle(); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 3c163cb..75b0629 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1506,11 +1506,12 @@ static inline void unregister_sched_domain_sysctl(void) } #endif -#else +extern void flush_smp_call_function_from_idle(void); +#else /* !CONFIG_SMP: */ +static inline void flush_smp_call_function_from_idle(void) { } static inline void sched_ttwu_pending(void) { } - -#endif /* CONFIG_SMP */ +#endif #include "stats.h" #include "autogroup.h" diff --git a/kernel/smp.c b/kernel/smp.c index f720e38..9f11813 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -135,6 +135,8 @@ static __always_inline void csd_unlock(call_single_data_t *csd) static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data); +extern void send_call_function_single_ipi(int cpu); + /* * Insert a previously allocated call_single_data_t element * for execution on the given CPU. data must already have @@ -178,7 +180,7 @@ static int generic_exec_single(int cpu, call_single_data_t *csd, * equipped to do the right thing... */ if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) - arch_send_call_function_single_ipi(cpu); + send_call_function_single_ipi(cpu); return 0; } @@ -278,6 +280,18 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline) } } +void flush_smp_call_function_from_idle(void) +{ + unsigned long flags; + + if (llist_empty(this_cpu_ptr(&call_single_queue))) + return; + + local_irq_save(flags); + flush_smp_call_function_queue(true); + local_irq_restore(flags); +} + /* * smp_call_function_single - Run a function on a specific CPU * @func: The function to run. This must be fast and non-blocking.