From patchwork Thu Mar 26 19:30:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Robert Foley X-Patchwork-Id: 11460855 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id ECAFA15AB for ; Thu, 26 Mar 2020 19:38:57 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id C367C20714 for ; Thu, 26 Mar 2020 19:38:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="vLtVk9Fr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C367C20714 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:58482 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHYLA-0007zF-Ty for patchwork-qemu-devel@patchwork.kernel.org; Thu, 26 Mar 2020 15:38:56 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58365) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHYJw-0005xv-Rv for qemu-devel@nongnu.org; Thu, 26 Mar 2020 15:37:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jHYJv-0001LV-95 for qemu-devel@nongnu.org; Thu, 26 Mar 2020 15:37:40 -0400 Received: from mail-qt1-x841.google.com ([2607:f8b0:4864:20::841]:43630) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1jHYJv-0001LG-4Q for qemu-devel@nongnu.org; Thu, 26 Mar 2020 15:37:39 -0400 Received: by mail-qt1-x841.google.com with SMTP id a5so6512831qtw.10 for ; Thu, 26 Mar 2020 12:37:39 -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=3hREnc0W2bwPSyTBH3eADGzgCMYeIoOKwLln3BCuEfI=; b=vLtVk9Fr4EjzAz5O9uxawwiQhIfYLsJNgTGeuriHcPeMQB69fnZPRLPQhVyDBhSpJz Y5JQKRQwv13H2lw0tG/YKcu07k2nUKrlfSpdTGvwEFDnDQiAY494J53lEN1c7DYZvCnM 6UL3NP+yUDdFTZ90oPQv24u5oiCL/RFUs1BScZ/Dy1WPYgynyJwWavYOqjR89VHZuPaA Le9NIbH4yYAl2exSbjk2tnC2rmxIOHsiSbsowvOaxhzPsRZxWu3PWqVaMTF8ksE3vEss 0Eb4Onn0/yO1NhXOWVWcH4CAPN0Ip8rk+vlaupV7Y1L5FVo1/0pQdqVbYltzGzneDKaO /8hA== 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=3hREnc0W2bwPSyTBH3eADGzgCMYeIoOKwLln3BCuEfI=; b=p6ZvST2qYltSMJ6+E/V8IVHMbtVscFL08W+e7MESKuNP9ZZ6hkvULbYKFZqcNw7htc /ZrS0W6HmckSC0hrKxqLQB7Tbhh+hKZ0X0vvwuqDfMJqrtOUPO8W8OjKa56g6X6g/7aV 8+JwKZZggYJ+MLbnyYWQflKjaEmMcMTsvKm9QmYK1bj9pBkZIOcyzT6gSAqqEckI9dh8 X0uvLTuiU09lg1Bz5SOm7sXoU6Rj7mhLnINF04eOnA5NObX1mecNZhKAcTl5PjnATHIr 3pyQK8C4wRprwE+vwl+zi8jZcjo/ozkOgJEgEFgDbVRYlQ3sClffdDmFC7sdz3GKoJs9 nvEg== X-Gm-Message-State: ANhLgQ1nccNx8Pl2Oa/Pb00mq9E7gWQAZ3k2oZv73wSvtQ+MO1IhrD6s 4ihhFwmZGtm/l3mYVvbDXvyTD8zy1gaqqA== X-Google-Smtp-Source: ADFU+vvfYlknMD12TI+6gT8txq8TKgskWtMlJoIvJeZPpjo9TNMGFdMrUWM6IV5E0DdUXFhpN10feg== X-Received: by 2002:ac8:2f88:: with SMTP id l8mr10238328qta.139.1585251457982; Thu, 26 Mar 2020 12:37:37 -0700 (PDT) Received: from Rfoley-MA01.hsd1.ma.comcast.net ([2601:199:4480:60c0:fd55:4e67:1038:8302]) by smtp.gmail.com with ESMTPSA id u51sm2161916qth.46.2020.03.26.12.37.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Mar 2020 12:37:37 -0700 (PDT) From: Robert Foley To: qemu-devel@nongnu.org Subject: [PATCH v8 04/74] cpu: make qemu_work_cond per-cpu Date: Thu, 26 Mar 2020 15:30:46 -0400 Message-Id: <20200326193156.4322-5-robert.foley@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200326193156.4322-1-robert.foley@linaro.org> References: <20200326193156.4322-1-robert.foley@linaro.org> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::841 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: richard.henderson@linaro.org, "Emilio G. Cota" , alex.bennee@linaro.org, robert.foley@linaro.org, peter.puhov@linaro.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.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 f75cae23d9..9031c31005 100644 --- a/cpus-common.c +++ b/cpus-common.c @@ -26,7 +26,6 @@ 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. @@ -42,7 +41,6 @@ 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) @@ -105,23 +103,37 @@ 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; } @@ -131,13 +143,34 @@ 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) @@ -303,6 +336,7 @@ 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)) { @@ -320,13 +354,23 @@ 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) { @@ -336,5 +380,5 @@ 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 633734fb5c..e1f3327bbc 100644 --- a/cpus.c +++ b/cpus.c @@ -1191,7 +1191,7 @@ 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 bc0416829a..6594323d77 100644 --- a/hw/core/cpu.c +++ b/hw/core/cpu.c @@ -368,6 +368,7 @@ 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 4521bba7a5..9c3ec715e2 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; @@ -769,12 +771,10 @@ 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: