On 04/04/2018 12:34, Alex Bennée wrote:
>
> Paolo Bonzini <pbonz...@redhat.com> writes:
>
>> Except for round-robin TCG, every other accelerator is using more or
>> less the same code around qemu_wait_io_event_common. The exception
>> is HAX, which also has to eat the dummy APC that is queued by
>> qemu_cpu_kick_thread.
>>
>> We can add the SleepEx call to qemu_wait_io_event under "if
>> (!tcg_enabled())", since that is the condition that is used in
>> qemu_cpu_kick_thread, and unify the function for KVM, HAX, HVF and
>> multi-threaded TCG. Single-threaded TCG code can also be simplified
>> since it is only used in the round-robin, sleep-if-all-CPUs-idle case.
>>
>> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
>
> I had trouble applying this patch but the change seems sane to me
>
> Acked-by: Alex Bennée <alex.ben...@linaro.org>
Isn't this commit db08b687cdd5319286665aabd34f82665630416f?
Paolo
>> ---
>> cpus.c | 49 +++++++++++++++++--------------------------------
>> 1 file changed, 17 insertions(+), 32 deletions(-)
>>
>> diff --git a/cpus.c b/cpus.c
>> index 440b9291f5..3b6c9879ec 100644
>> --- a/cpus.c
>> +++ b/cpus.c
>> @@ -911,7 +911,8 @@ static void kick_tcg_thread(void *opaque)
>>
>> static void start_tcg_kick_timer(void)
>> {
>> - if (!mttcg_enabled && !tcg_kick_vcpu_timer && CPU_NEXT(first_cpu)) {
>> + assert(!mttcg_enabled);
>> + if (!tcg_kick_vcpu_timer && CPU_NEXT(first_cpu)) {
>> tcg_kick_vcpu_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
>> kick_tcg_thread, NULL);
>> timer_mod(tcg_kick_vcpu_timer, qemu_tcg_next_kick());
>> @@ -920,6 +921,7 @@ static void start_tcg_kick_timer(void)
>>
>> static void stop_tcg_kick_timer(void)
>> {
>> + assert(!mttcg_enabled);
>> if (tcg_kick_vcpu_timer) {
>> timer_del(tcg_kick_vcpu_timer);
>> tcg_kick_vcpu_timer = NULL;
>> @@ -1154,18 +1156,9 @@ static void qemu_wait_io_event_common(CPUState *cpu)
>> process_queued_cpu_work(cpu);
>> }
>>
>> -static bool qemu_tcg_should_sleep(CPUState *cpu)
>> +static void qemu_tcg_rr_wait_io_event(CPUState *cpu)
>> {
>> - if (mttcg_enabled) {
>> - return cpu_thread_is_idle(cpu);
>> - } else {
>> - return all_cpu_threads_idle();
>> - }
>> -}
>> -
>> -static void qemu_tcg_wait_io_event(CPUState *cpu)
>> -{
>> - while (qemu_tcg_should_sleep(cpu)) {
>> + while (all_cpu_threads_idle()) {
>> stop_tcg_kick_timer();
>> qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex);
>> }
>> @@ -1175,20 +1168,18 @@ static void qemu_tcg_wait_io_event(CPUState *cpu)
>> qemu_wait_io_event_common(cpu);
>> }
>>
>> -static void qemu_kvm_wait_io_event(CPUState *cpu)
>> +static void qemu_wait_io_event(CPUState *cpu)
>> {
>> while (cpu_thread_is_idle(cpu)) {
>> qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex);
>> }
>>
>> - qemu_wait_io_event_common(cpu);
>> -}
>> -
>> -static void qemu_hvf_wait_io_event(CPUState *cpu)
>> -{
>> - while (cpu_thread_is_idle(cpu)) {
>> - qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex);
>> +#ifdef _WIN32
>> + /* Eat dummy APC queued by qemu_cpu_kick_thread. */
>> + if (!tcg_enabled()) {
>> + SleepEx(0, TRUE);
>> }
>> +#endif
>> qemu_wait_io_event_common(cpu);
>> }
>>
>> @@ -1224,7 +1215,7 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
>> cpu_handle_guest_debug(cpu);
>> }
>> }
>> - qemu_kvm_wait_io_event(cpu);
>> + qemu_wait_io_event(cpu);
>> } while (!cpu->unplug || cpu_can_run(cpu));
>>
>> qemu_kvm_destroy_vcpu(cpu);
>> @@ -1270,7 +1261,7 @@ static void *qemu_dummy_cpu_thread_fn(void *arg)
>> exit(1);
>> }
>> qemu_mutex_lock_iothread();
>> - qemu_wait_io_event_common(cpu);
>> + qemu_wait_io_event(cpu);
>> }
>>
>> return NULL;
>> @@ -1487,7 +1478,7 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg)
>> atomic_mb_set(&cpu->exit_request, 0);
>> }
>>
>> - qemu_tcg_wait_io_event(cpu ? cpu : QTAILQ_FIRST(&cpus));
>> + qemu_tcg_rr_wait_io_event(cpu ? cpu : QTAILQ_FIRST(&cpus));
>> deal_with_unplugged_cpus();
>> }
>>
>> @@ -1518,13 +1509,7 @@ static void *qemu_hax_cpu_thread_fn(void *arg)
>> }
>> }
>>
>> - while (cpu_thread_is_idle(cpu)) {
>> - qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex);
>> - }
>> -#ifdef _WIN32
>> - SleepEx(0, TRUE);
>> -#endif
>> - qemu_wait_io_event_common(cpu);
>> + qemu_wait_io_event(cpu);
>> }
>> return NULL;
>> }
>> @@ -1561,7 +1546,7 @@ static void *qemu_hvf_cpu_thread_fn(void *arg)
>> cpu_handle_guest_debug(cpu);
>> }
>> }
>> - qemu_hvf_wait_io_event(cpu);
>> + qemu_wait_io_event(cpu);
>> } while (!cpu->unplug || cpu_can_run(cpu));
>>
>> hvf_vcpu_destroy(cpu);
>> @@ -1640,7 +1625,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
>> }
>>
>> atomic_mb_set(&cpu->exit_request, 0);
>> - qemu_tcg_wait_io_event(cpu);
>> + qemu_wait_io_event(cpu);
>> }
>>
>> return NULL;
>
>
> --
> Alex Bennée
>
