From patchwork Tue Mar 28 19:57:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13191500 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 87E82C761A6 for ; Tue, 28 Mar 2023 19:58:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229844AbjC1T6v (ORCPT ); Tue, 28 Mar 2023 15:58:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42944 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229749AbjC1T6o (ORCPT ); Tue, 28 Mar 2023 15:58:44 -0400 Received: from mail-wr1-x430.google.com (mail-wr1-x430.google.com [IPv6:2a00:1450:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4C0340C7 for ; Tue, 28 Mar 2023 12:58:07 -0700 (PDT) Received: by mail-wr1-x430.google.com with SMTP id d17so13391345wrb.11 for ; Tue, 28 Mar 2023 12:58:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1680033486; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=bAkcK9PzxRDXKfC6w4H8Cy8JdU/8fLLXDQn0J84D/Q4=; b=brv1zXiAmPh91aE9DjrwGIwaZCqLhuvVSUYlRm0V3wR7uEEO1zHVL025Y1YIIYZiat pUB8v5LNzBgwFFuuF3/fAKGDzC+mIbKI6KjByKrIwOimDShFX33xBmwE5/8LUVsNBNoX AZ7eDARNreOKVYr0zxRJIZgTARIchcvEoVso2Q5dAEWC7mp/nM8yObn0/3t0xPpFubhc OSHWuRVlzVQB9Ix8KSIr0ej4xjcbc6IsctflpnmbFM2HAyxH5SG3R0KkvUKj8AtCzBUt 64OGHO/C/OkRi7qKR0lWy3qMQZgKqIqijf4J+6VfGUZ88OZZPWC3VspC+F5K7RUr5RwA jd8Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680033486; 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:message-id:reply-to; bh=bAkcK9PzxRDXKfC6w4H8Cy8JdU/8fLLXDQn0J84D/Q4=; b=jR3Iy+1ZK/NqyxdQpr0GrKzp0UEWRizbThGiX9XYtINP2whSL6QAMSfx/egdnjGWmQ CZeZW30GXNJuzTjngZ9NJkMITAmi0pZY0GG5cX4U9kEB4rp8szf4V+SEtkOQhR18YAkF 112Tngs6NgT/+WJ1nnAAAjZZzCDb/um33+EcoSNkXcvLIPROGrGXELKBFN3BSiTmAZsQ cXhY1Y3kY4kl5twb/lZoVqunJij9xdRGkjZHxJQSk/dTLShKJpqUPI1MA+CG/ODKhjFr oM1LgfKGcL4No+P56TbwLyaL5HLTjnyLaXM2vPMdo3JkDkqcHmrmTBYli+trGlStLLkZ K1/A== X-Gm-Message-State: AAQBX9d0bDdt3fBsNWFJa2EroI8imO5H98uQQI1N0sd02Ef2UH5RUbE5 +WabqmvTkX4ZQx6i1Ew5OJuBTA== X-Google-Smtp-Source: AKy350b0sqZML6UggFbY6k1sToHWoQVpdKzomiPn9RGxAnCWYkTkvqqG8QpnuZfgKmjwoe0QILN/hA== X-Received: by 2002:adf:e405:0:b0:2cc:1935:1ae8 with SMTP id g5-20020adfe405000000b002cc19351ae8mr12975394wrm.47.1680033486292; Tue, 28 Mar 2023 12:58:06 -0700 (PDT) Received: from usaari01.cust.communityfibre.co.uk ([2a02:6b6a:b566:0:8445:3123:91d7:959d]) by smtp.gmail.com with ESMTPSA id z6-20020a056000110600b002c557f82e27sm28248386wrw.99.2023.03.28.12.58.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Mar 2023 12:58:05 -0700 (PDT) From: Usama Arif To: dwmw2@infradead.org, tglx@linutronix.de, kim.phillips@amd.com, brgerst@gmail.com Cc: piotrgorski@cachyos.org, oleksandr@natalenko.name, arjan@linux.intel.com, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com, paulmck@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com, thomas.lendacky@amd.com, seanjc@google.com, pmenzel@molgen.mpg.de, fam.zheng@bytedance.com, punit.agrawal@bytedance.com, simon.evans@bytedance.com, liangma@liangbit.com, gpiccoli@igalia.com, David Woodhouse , Usama Arif Subject: [PATCH v17 6/8] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel Date: Tue, 28 Mar 2023 20:57:56 +0100 Message-Id: <20230328195758.1049469-7-usama.arif@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230328195758.1049469-1-usama.arif@bytedance.com> References: <20230328195758.1049469-1-usama.arif@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: David Woodhouse When the APs can find their own APIC ID without assistance, perform the AP bringup in parallel. Register a CPUHP_BP_PARALLEL_STARTUP stage "x86/cpu:kick" which just calls do_boot_cpu() to deliver INIT/SIPI/SIPI to each AP in turn before the normal native_cpu_up() does the rest of the hand-holding. The APs will then take turns through the real mode code (which has its own bitlock for exclusion) until they make it to their own stack, then proceed through the first few lines of start_secondary() and execute these parts in parallel: start_secondary() -> cr4_init() -> (some 32-bit only stuff so not in the parallel cases) -> cpu_init_secondary() -> cpu_init_exception_handling() -> cpu_init() -> wait_for_master_cpu() At this point they wait for the BSP to set their bit in cpu_callout_mask (from do_wait_cpu_initialized()), and release them to continue through the rest of cpu_init() and beyond. This reduces the time taken for bringup on my 28-thread Haswell system from about 120ms to 80ms. On a socket 96-thread Skylake it takes the bringup time from 500ms to 100ms. Signed-off-by: David Woodhouse Signed-off-by: Usama Arif Tested-by: Paul E. McKenney Tested-by: Kim Phillips Tested-by: Oleksandr Natalenko Tested-by: Guilherme G. Piccoli --- arch/x86/kernel/smpboot.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 45f3d08321fe..0003f5e1740c 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -57,6 +57,7 @@ #include #include #include +#include #include #include @@ -993,7 +994,8 @@ static void announce_cpu(int cpu, int apicid) node_width = num_digits(num_possible_nodes()) + 1; /* + '#' */ if (cpu == 1) - printk(KERN_INFO "x86: Booting SMP configuration:\n"); + printk(KERN_INFO "x86: Booting SMP configuration in %s:\n", + do_parallel_bringup ? "parallel" : "series"); if (system_state < SYSTEM_RUNNING) { if (node != current_node) { @@ -1326,9 +1328,12 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) { int ret; - ret = do_cpu_up(cpu, tidle); - if (ret) - goto out; + /* If parallel AP bringup isn't enabled, perform the first steps now. */ + if (!do_parallel_bringup) { + ret = do_cpu_up(cpu, tidle); + if (ret) + goto out; + } ret = do_wait_cpu_initialized(cpu); if (ret) @@ -1348,6 +1353,12 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) return ret; } +/* Bringup step one: Send INIT/SIPI to the target AP */ +static int native_cpu_kick(unsigned int cpu) +{ + return do_cpu_up(cpu, idle_thread_get(cpu)); +} + /** * arch_disable_smp_support() - disables SMP support for x86 at runtime */ @@ -1516,6 +1527,8 @@ static bool prepare_parallel_bringup(void) smpboot_control = STARTUP_APICID_CPUID_01; } + cpuhp_setup_state_nocalls(CPUHP_BP_PARALLEL_STARTUP, "x86/cpu:kick", + native_cpu_kick, NULL); return true; }