From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58628) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gDJFR-0004UK-4z for qemu-devel@nongnu.org; Thu, 18 Oct 2018 21:06:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gDJFN-0002my-1P for qemu-devel@nongnu.org; Thu, 18 Oct 2018 21:06:40 -0400 Received: from out5-smtp.messagingengine.com ([66.111.4.29]:52709) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gDJFM-0002aO-6T for qemu-devel@nongnu.org; Thu, 18 Oct 2018 21:06:36 -0400 From: "Emilio G. Cota" Date: Thu, 18 Oct 2018 21:05:33 -0400 Message-Id: <20181019010625.25294-5-cota@braap.org> In-Reply-To: <20181019010625.25294-1-cota@braap.org> References: <20181019010625.25294-1-cota@braap.org> Subject: [Qemu-devel] [RFC v3 04/56] cpu: make qemu_work_cond per-cpu List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Peter Crosthwaite , Richard Henderson 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. Cc: Peter Crosthwaite Cc: Richard Henderson Signed-off-by: Emilio G. Cota --- include/qom/cpu.h | 6 +++--- cpus-common.c | 48 ++++++++++++++++++++++++++++++++++------------- cpus.c | 2 +- qom/cpu.c | 1 + 4 files changed, 40 insertions(+), 17 deletions(-) diff --git a/include/qom/cpu.h b/include/qom/cpu.h index 1292e7aa33..82937881ef 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -316,6 +316,7 @@ struct qemu_work_item; * @mem_io_vaddr: Target virtual address at which the memory was accessed. * @kvm_fd: vCPU file descriptor for KVM. * @lock: Lock to prevent multiple access to per-CPU fields. + * @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). @@ -358,6 +359,7 @@ struct CPUState { QemuMutex lock; /* fields below protected by @lock */ + QemuCond cond; QSIMPLEQ_HEAD(, qemu_work_item) work_list; CPUAddressSpace *cpu_ases; @@ -762,12 +764,10 @@ 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: diff --git a/cpus-common.c b/cpus-common.c index 2913294cb7..2881707c35 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) @@ -113,39 +111,52 @@ 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; + g_assert(qemu_mutex_iothread_locked()); + if (qemu_cpu_is_self(cpu)) { func(cpu, data); return; } + qemu_mutex_unlock_iothread(); + wi.func = func; wi.data = data; wi.done = false; wi.free = false; wi.exclusive = false; - queue_work_on_cpu(cpu, &wi); + cpu_mutex_lock(cpu); + queue_work_on_cpu_locked(cpu, &wi); 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); + + qemu_mutex_lock_iothread(); } void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data) @@ -307,6 +318,7 @@ 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)) { @@ -324,13 +336,23 @@ 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) { @@ -340,5 +362,5 @@ 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 a190651653..e844335386 100644 --- a/cpus.c +++ b/cpus.c @@ -1236,7 +1236,7 @@ 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/qom/cpu.c b/qom/cpu.c index d0758c907d..bb031a3a6a 100644 --- a/qom/cpu.c +++ b/qom/cpu.c @@ -373,6 +373,7 @@ 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); -- 2.17.1