From: Robert Foley <robert.foley@linaro.org> To: qemu-devel@nongnu.org Cc: richard.henderson@linaro.org, "Emilio G. Cota" <cota@braap.org>, alex.bennee@linaro.org, robert.foley@linaro.org, peter.puhov@linaro.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> (raw) In-Reply-To: <20200326193156.4322-1-robert.foley@linaro.org> From: "Emilio G. Cota" <cota@braap.org> 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 <richard.henderson@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Robert Foley <robert.foley@linaro.org> --- 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: -- 2.17.1
next prev parent reply index Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-26 19:30 [PATCH v8 00/74] per-CPU locks Robert Foley 2020-03-26 19:30 ` [PATCH v8 01/74] cpu: convert queued work to a QSIMPLEQ Robert Foley 2020-03-26 19:30 ` [PATCH v8 02/74] cpu: rename cpu->work_mutex to cpu->lock Robert Foley 2020-05-11 14:48 ` Alex Bennée 2020-05-11 16:33 ` Robert Foley 2020-03-26 19:30 ` [PATCH v8 03/74] cpu: introduce cpu_mutex_lock/unlock Robert Foley 2020-05-11 10:24 ` Alex Bennée 2020-05-11 16:09 ` Robert Foley 2020-03-26 19:30 ` Robert Foley [this message] 2020-03-26 19:30 ` [PATCH v8 05/74] cpu: move run_on_cpu to cpus-common Robert Foley 2020-03-26 19:30 ` [PATCH v8 06/74] cpu: introduce process_queued_cpu_work_locked Robert Foley 2020-03-26 19:30 ` [PATCH v8 07/74] cpu: make per-CPU locks an alias of the BQL in TCG rr mode Robert Foley 2020-03-26 19:30 ` [PATCH v8 08/74] tcg-runtime: define helper_cpu_halted_set Robert Foley 2020-03-26 19:30 ` [PATCH v8 09/74] ppc: convert to helper_cpu_halted_set Robert Foley 2020-03-26 19:30 ` [PATCH v8 10/74] cris: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 11/74] hppa: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 12/74] m68k: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 13/74] alpha: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 14/74] microblaze: " Robert Foley 2020-03-26 19:30 ` [PATCH v8 15/74] cpu: define cpu_halted helpers Robert Foley 2020-03-26 19:30 ` [PATCH v8 16/74] tcg-runtime: convert to cpu_halted_set Robert Foley 2020-03-26 19:30 ` [PATCH v8 17/74] hw/semihosting: " Robert Foley 2020-05-11 10:25 ` Alex Bennée 2020-03-26 19:31 ` [PATCH v8 18/74] arm: convert to cpu_halted Robert Foley 2020-03-26 19:31 ` [PATCH v8 19/74] ppc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 20/74] sh4: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 21/74] i386: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 22/74] lm32: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 23/74] m68k: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 24/74] mips: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 25/74] riscv: " Robert Foley 2020-05-11 10:40 ` Alex Bennée 2020-05-11 16:13 ` Robert Foley 2020-03-26 19:31 ` [PATCH v8 26/74] s390x: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 27/74] sparc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 28/74] xtensa: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 29/74] gdbstub: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 30/74] openrisc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 31/74] cpu-exec: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 32/74] cpu: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 33/74] cpu: define cpu_interrupt_request helpers Robert Foley 2020-03-26 19:31 ` [PATCH v8 34/74] ppc: use cpu_reset_interrupt Robert Foley 2020-03-26 19:31 ` [PATCH v8 35/74] exec: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 36/74] i386: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 37/74] s390x: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 38/74] openrisc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 39/74] arm: convert to cpu_interrupt_request Robert Foley 2020-03-26 19:31 ` [PATCH v8 40/74] i386: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 41/74] i386/kvm: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 42/74] i386/hax-all: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 43/74] i386/whpx-all: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 44/74] i386/hvf: convert to cpu_request_interrupt Robert Foley 2020-03-26 19:31 ` [PATCH v8 45/74] ppc: convert to cpu_interrupt_request Robert Foley 2020-03-26 19:31 ` [PATCH v8 46/74] sh4: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 47/74] cris: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 48/74] hppa: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 49/74] lm32: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 50/74] m68k: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 51/74] mips: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 52/74] nios: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 53/74] s390x: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 54/74] alpha: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 55/74] moxie: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 56/74] sparc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 57/74] openrisc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 58/74] unicore32: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 59/74] microblaze: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 60/74] accel/tcg: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 61/74] cpu: convert to interrupt_request Robert Foley 2020-03-26 19:31 ` [PATCH v8 62/74] cpu: call .cpu_has_work with the CPU lock held Robert Foley 2020-03-26 19:31 ` [PATCH v8 63/74] cpu: introduce cpu_has_work_with_iothread_lock Robert Foley 2020-03-26 19:31 ` [PATCH v8 64/74] ppc: convert to cpu_has_work_with_iothread_lock Robert Foley 2020-03-26 19:31 ` [PATCH v8 65/74] mips: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 66/74] s390x: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 67/74] riscv: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 68/74] sparc: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 69/74] xtensa: " Robert Foley 2020-03-26 19:31 ` [PATCH v8 70/74] cpu: rename all_cpu_threads_idle to qemu_tcg_rr_all_cpu_threads_idle Robert Foley 2020-03-26 19:31 ` [PATCH v8 71/74] cpu: protect CPU state with cpu->lock instead of the BQL Robert Foley 2020-03-26 19:31 ` [PATCH v8 72/74] cpus-common: release BQL earlier in run_on_cpu Robert Foley 2020-03-26 19:31 ` [PATCH v8 73/74] cpu: add async_run_on_cpu_no_bql Robert Foley 2020-03-26 19:31 ` [PATCH v8 74/74] cputlb: queue async flush jobs without the BQL Robert Foley 2020-05-12 16:27 ` Alex Bennée 2020-05-12 19:26 ` Robert Foley 2020-05-18 13:46 ` Robert Foley 2020-05-20 4:46 ` Emilio G. Cota 2020-05-20 15:01 ` Robert Foley 2020-05-21 14:17 ` Robert Foley 2020-05-12 18:38 ` Alex Bennée 2020-03-26 22:58 ` [PATCH v8 00/74] per-CPU locks Aleksandar Markovic 2020-03-27 9:39 ` Alex Bennée 2020-03-27 9:50 ` Aleksandar Markovic 2020-03-27 10:24 ` Aleksandar Markovic 2020-03-27 17:21 ` Robert Foley 2020-03-27 5:14 ` Emilio G. Cota 2020-03-27 10:59 ` Philippe Mathieu-Daudé 2020-03-30 8:57 ` Stefan Hajnoczi 2020-03-27 18:23 ` Alex Bennée 2020-03-27 18:30 ` Robert Foley 2020-05-12 16:29 ` Alex Bennée
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