From patchwork Wed Jun 17 21:01:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Robert Foley X-Patchwork-Id: 1311525 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256 header.s=google header.b=Zt4xqudC; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 49nHgF2ZW1z9sSJ for ; Thu, 18 Jun 2020 07:06:33 +1000 (AEST) Received: from localhost ([::1]:42258 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jlfGR-0006VM-23 for incoming@patchwork.ozlabs.org; Wed, 17 Jun 2020 17:06:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36886) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jlfDS-0002dT-2G for qemu-devel@nongnu.org; Wed, 17 Jun 2020 17:03:26 -0400 Received: from mail-qt1-x841.google.com ([2607:f8b0:4864:20::841]:36374) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jlfDO-0008Pv-Co for qemu-devel@nongnu.org; Wed, 17 Jun 2020 17:03:25 -0400 Received: by mail-qt1-x841.google.com with SMTP id w9so2761265qtv.3 for ; Wed, 17 Jun 2020 14:03:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=pQeS3ErQJYe6lUMZTvW4HI5IzahbrklWfBxpVQvJbIg=; b=Zt4xqudCRQ0OUAqxQ8rsAwSTaiB7Ot9EnCA+XPlHCfM1HpEPiuTaGSlQNU0nM6R9Xk zsqX3HrWFtcYLMkGwt1QkSmVLIrKyj3jLzV6YHigqNioDLLu1PIlxhw7KpT7CgIQfxyC gvSWI5KSo3ZoZCU3Y6d9+6H33bnrC51Wp004WhWtTQ+/tHxbajTZsk0NemVmPNI+0NLJ k1cW6nIIXIHSEBbCWywd8U+Ddz9dMdtShANprE9XMWnEjUijiz0ReLu2s3oh0Cmn5vfY MQRHNFPpeVdJQUBsguK3NunKDflIpP0dVdQRwmc++ZxCV65ZXISsPWrIyMLIdXn0SU8L LROg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=pQeS3ErQJYe6lUMZTvW4HI5IzahbrklWfBxpVQvJbIg=; b=oif95DmAGlL9BX/bVxXa33TW7vjm4CEz1jL8ZfxyAdjJDaYg0LSDL2v2OSnv4CEvNt /4ZPp8YKYufo1dQ/OP7+TDEaRBLDFRmLwpJmnrxa1d4h5Cw06NJh7bkEAmACXORJAmHY KzkACe9PMJrtvEkmWDLc3EMHRco836gv8n4y+aiJxTCECD9JlaOqLGHsW54FesJlQEx+ 6qsO8Bq4MCMCLxEvlmzb2enuEZsFNjDb3j4D4mY7QPwpKae+Ucn4jfcBUUVXfUmj63Aq U99yKJUj5C8TlZiN/L+9+YDVuChNlir/VdiPXcDKnXrptkkeKjXd6Q3ojVAMhCqDGNDX gE6g== X-Gm-Message-State: AOAM532r3pmvVFL5/Y9Gajhbsfhfh4Wp1BHTyOMPoUfz+DCUweeFTHti 3OW7knNN3dK949PPkm9vZkrii/1/CVU74g== X-Google-Smtp-Source: ABdhPJwm4Prd7s/y/OVV2BowxMoBKxWpU3jOeN1DGr3xq9PrniQQLBtETI11mggJBHQtC9Aa+9B4oA== X-Received: by 2002:ac8:538b:: with SMTP id x11mr1116947qtp.84.1592427799432; Wed, 17 Jun 2020 14:03:19 -0700 (PDT) Received: from Rfoley-MA01.hsd1.ma.comcast.net ([2601:199:4480:60c0:fc79:714c:9711:2e9c]) by smtp.gmail.com with ESMTPSA id w13sm997245qkb.91.2020.06.17.14.03.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jun 2020 14:03:18 -0700 (PDT) From: Robert Foley To: qemu-devel@nongnu.org Subject: [PATCH v10 03/73] cpu: make qemu_work_cond per-cpu Date: Wed, 17 Jun 2020 17:01:21 -0400 Message-Id: <20200617210231.4393-4-robert.foley@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200617210231.4393-1-robert.foley@linaro.org> References: <20200617210231.4393-1-robert.foley@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::841; envelope-from=robert.foley@linaro.org; helo=mail-qt1-x841.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: robert.foley@linaro.org, Eduardo Habkost , cota@braap.org, Paolo Bonzini , peter.puhov@linaro.org, alex.bennee@linaro.org, Richard Henderson Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: "Emilio G. Cota" This eliminates the need to use the BQL to queue CPU work. While at it, give the per-cpu field a generic name ("cond") since it will soon be used for more than just queueing CPU work. Reviewed-by: Richard Henderson Reviewed-by: Alex Bennée Signed-off-by: Emilio G. Cota Signed-off-by: Robert Foley --- cpus-common.c | 72 ++++++++++++++++++++++++++++++++++--------- cpus.c | 2 +- hw/core/cpu.c | 1 + include/hw/core/cpu.h | 6 ++-- 4 files changed, 63 insertions(+), 18 deletions(-) diff --git a/cpus-common.c b/cpus-common.c index 622430bd33..57d9fc6ea1 100644 --- a/cpus-common.c +++ b/cpus-common.c @@ -27,7 +27,6 @@ static QemuMutex qemu_cpu_list_lock; static QemuCond exclusive_cond; static QemuCond exclusive_resume; -static QemuCond qemu_work_cond; /* >= 1 if a thread is inside start_exclusive/end_exclusive. Written * under qemu_cpu_list_lock, read with atomic operations. @@ -43,7 +42,6 @@ void qemu_init_cpu_list(void) qemu_mutex_init(&qemu_cpu_list_lock); qemu_cond_init(&exclusive_cond); qemu_cond_init(&exclusive_resume); - qemu_cond_init(&qemu_work_cond); } void cpu_list_lock(void) @@ -103,23 +101,37 @@ struct qemu_work_item { bool free, exclusive, done; }; -static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi) +/* Called with the CPU's lock held */ +static void queue_work_on_cpu_locked(CPUState *cpu, struct qemu_work_item *wi) { - qemu_mutex_lock(&cpu->lock); QSIMPLEQ_INSERT_TAIL(&cpu->work_list, wi, node); wi->done = false; - qemu_mutex_unlock(&cpu->lock); qemu_cpu_kick(cpu); } -void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data, - QemuMutex *mutex) +static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi) +{ + cpu_mutex_lock(cpu); + queue_work_on_cpu_locked(cpu, wi); + cpu_mutex_unlock(cpu); +} + +void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data) { struct qemu_work_item wi; + bool has_bql = qemu_mutex_iothread_locked(); + + g_assert(no_cpu_mutex_locked()); if (qemu_cpu_is_self(cpu)) { - func(cpu, data); + if (has_bql) { + func(cpu, data); + } else { + qemu_mutex_lock_iothread(); + func(cpu, data); + qemu_mutex_unlock_iothread(); + } return; } @@ -129,13 +141,34 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data, wi.free = false; wi.exclusive = false; - queue_work_on_cpu(cpu, &wi); + cpu_mutex_lock(cpu); + queue_work_on_cpu_locked(cpu, &wi); + + /* + * We are going to sleep on the CPU lock, so release the BQL. + * + * During the transition to per-CPU locks, we release the BQL _after_ + * having kicked the destination CPU (from queue_work_on_cpu_locked above). + * This makes sure that the enqueued work will be seen by the CPU + * after being woken up from the kick, since the CPU sleeps on the BQL. + * Once we complete the transition to per-CPU locks, we will release + * the BQL earlier in this function. + */ + if (has_bql) { + qemu_mutex_unlock_iothread(); + } + while (!atomic_mb_read(&wi.done)) { CPUState *self_cpu = current_cpu; - qemu_cond_wait(&qemu_work_cond, mutex); + qemu_cond_wait(&cpu->cond, &cpu->lock); current_cpu = self_cpu; } + cpu_mutex_unlock(cpu); + + if (has_bql) { + qemu_mutex_lock_iothread(); + } } void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data) @@ -299,6 +332,7 @@ void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void process_queued_cpu_work(CPUState *cpu) { struct qemu_work_item *wi; + bool has_bql = qemu_mutex_iothread_locked(); qemu_mutex_lock(&cpu->lock); if (QSIMPLEQ_EMPTY(&cpu->work_list)) { @@ -316,13 +350,23 @@ void process_queued_cpu_work(CPUState *cpu) * BQL, so it goes to sleep; start_exclusive() is sleeping too, so * neither CPU can proceed. */ - qemu_mutex_unlock_iothread(); + if (has_bql) { + qemu_mutex_unlock_iothread(); + } start_exclusive(); wi->func(cpu, wi->data); end_exclusive(); - qemu_mutex_lock_iothread(); + if (has_bql) { + qemu_mutex_lock_iothread(); + } } else { - wi->func(cpu, wi->data); + if (has_bql) { + wi->func(cpu, wi->data); + } else { + qemu_mutex_lock_iothread(); + wi->func(cpu, wi->data); + qemu_mutex_unlock_iothread(); + } } qemu_mutex_lock(&cpu->lock); if (wi->free) { @@ -332,5 +376,5 @@ void process_queued_cpu_work(CPUState *cpu) } } qemu_mutex_unlock(&cpu->lock); - qemu_cond_broadcast(&qemu_work_cond); + qemu_cond_broadcast(&cpu->cond); } diff --git a/cpus.c b/cpus.c index ca271411a4..035f41a997 100644 --- a/cpus.c +++ b/cpus.c @@ -1216,7 +1216,7 @@ void qemu_init_cpu_loop(void) void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data) { - do_run_on_cpu(cpu, func, data, &qemu_global_mutex); + do_run_on_cpu(cpu, func, data); } static void qemu_kvm_destroy_vcpu(CPUState *cpu) diff --git a/hw/core/cpu.c b/hw/core/cpu.c index 1cba5b6e69..07251d83df 100644 --- a/hw/core/cpu.c +++ b/hw/core/cpu.c @@ -370,6 +370,7 @@ static void cpu_common_initfn(Object *obj) cpu->nr_threads = 1; qemu_mutex_init(&cpu->lock); + qemu_cond_init(&cpu->cond); QSIMPLEQ_INIT(&cpu->work_list); QTAILQ_INIT(&cpu->breakpoints); QTAILQ_INIT(&cpu->watchpoints); diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h index 4d4006f1fb..ebff239ad3 100644 --- a/include/hw/core/cpu.h +++ b/include/hw/core/cpu.h @@ -333,6 +333,7 @@ struct qemu_work_item; * @kvm_fd: vCPU file descriptor for KVM. * @lock: Lock to prevent multiple access to per-CPU fields. Must be acquired * after the BQL. + * @cond: Condition variable for per-CPU events. * @work_list: List of pending asynchronous work. * @trace_dstate_delayed: Delayed changes to trace_dstate (includes all changes * to @trace_dstate). @@ -378,6 +379,7 @@ struct CPUState { QemuMutex lock; /* fields below protected by @lock */ + QemuCond cond; QSIMPLEQ_HEAD(, qemu_work_item) work_list; CPUAddressSpace *cpu_ases; @@ -774,12 +776,10 @@ bool cpu_is_stopped(CPUState *cpu); * @cpu: The vCPU to run on. * @func: The function to be executed. * @data: Data to pass to the function. - * @mutex: Mutex to release while waiting for @func to run. * * Used internally in the implementation of run_on_cpu. */ -void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data, - QemuMutex *mutex); +void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data); /** * run_on_cpu: