Re: [Qemu-devel] [PATCH 02/10] cpus: remove tcg_halt_cond global variable.

[Frederic Konrad <fred.konrad@greensocs.com>]

On 12/08/2015 18:40, Paolo Bonzini wrote:
> From: KONRAD Frederic <fred.konrad@greensocs.com>
>
> This removes tcg_halt_cond global variable.
> We need one QemuCond per virtual cpu for multithread TCG.
>
> Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
> Message-Id: <1439220437-23957-9-git-send-email-fred.konrad@greensocs.com>
> [Keep tcg_halt_cond for bisectability, while making it static. - Paolo]
How does that help bisectability?

Fred
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   cpus.c | 12 +++++-------
>   1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/cpus.c b/cpus.c
> index 9224488..8884278 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -813,7 +813,6 @@ static unsigned iothread_requesting_mutex;
>   static QemuThread io_thread;
>   
>   static QemuThread *tcg_cpu_thread;
> -static QemuCond *tcg_halt_cond;
>   
>   /* cpu creation */
>   static QemuCond qemu_cpu_cond;
> @@ -933,15 +932,13 @@ static void qemu_wait_io_event_common(CPUState *cpu)
>       cpu->thread_kicked = false;
>   }
>   
> -static void qemu_tcg_wait_io_event(void)
> +static void qemu_tcg_wait_io_event(CPUState *cpu)
>   {
> -    CPUState *cpu;
> -
>       while (all_cpu_threads_idle()) {
>          /* Start accounting real time to the virtual clock if the CPUs
>             are idle.  */
>           qemu_clock_warp(QEMU_CLOCK_VIRTUAL);
> -        qemu_cond_wait(tcg_halt_cond, &qemu_global_mutex);
> +        qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex);
>       }
>   
>       while (iothread_requesting_mutex) {
> @@ -1067,7 +1064,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
>   
>       /* wait for initial kick-off after machine start */
>       while (first_cpu->stopped) {
> -        qemu_cond_wait(tcg_halt_cond, &qemu_global_mutex);
> +        qemu_cond_wait(first_cpu->halt_cond, &qemu_global_mutex);
>   
>           /* process any pending work */
>           CPU_FOREACH(cpu) {
> @@ -1088,7 +1085,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
>                   qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
>               }
>           }
> -        qemu_tcg_wait_io_event();
> +        qemu_tcg_wait_io_event(QTAILQ_FIRST(&cpus));
>       }
>   
>       return NULL;
> @@ -1265,6 +1262,7 @@ void resume_all_vcpus(void)
>   static void qemu_tcg_init_vcpu(CPUState *cpu)
>   {
>       char thread_name[VCPU_THREAD_NAME_SIZE];
> +    static QemuCond *tcg_halt_cond;
>   
>       tcg_cpu_address_space_init(cpu, cpu->as);
>