Re: [Qemu-devel] [RFC 01/48] cpu: introduce run_on_cpu_no_bql

["Alex Bennée" <alex.bennee@linaro.org>]

Emilio G. Cota <cota@braap.org> writes:

> This allows us to queue synchronous CPU work without the BQL.
>
> Will gain a user soon.

This is also in the cpu-lock series right?

>
> Signed-off-by: Emilio G. Cota <cota@braap.org>
> ---
>  include/qom/cpu.h | 13 +++++++++++++
>  cpus-common.c     | 28 ++++++++++++++++++++++------
>  2 files changed, 35 insertions(+), 6 deletions(-)
>
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 204bc94056..863aa2bff1 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -877,6 +877,19 @@ bool cpu_is_stopped(CPUState *cpu);
>   */
>  void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data);
>
> +/**
> + * run_on_cpu_no_bql
> + * @cpu: The vCPU to run on.
> + * @func: The function to be executed.
> + * @data: Data to pass to the function.
> + *
> + * Schedules the function @func for execution on the vCPU @cpu.
> + * This function is run outside the BQL.
> + * See also: run_on_cpu()
> + */
> +void run_on_cpu_no_bql(CPUState *cpu, run_on_cpu_func func,
> +                       run_on_cpu_data data);
> +
>  /**
>   * async_run_on_cpu:
>   * @cpu: The vCPU to run on.
> diff --git a/cpus-common.c b/cpus-common.c
> index cffb2b71ac..b478fc8741 100644
> --- a/cpus-common.c
> +++ b/cpus-common.c
> @@ -144,7 +144,8 @@ static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
>      cpu_mutex_unlock(cpu);
>  }
>
> -void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
> +static void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func,
> +                          run_on_cpu_data data, bool bql)
>  {
>      struct qemu_work_item wi;
>      bool has_bql = qemu_mutex_iothread_locked();
> @@ -152,12 +153,16 @@ void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
>      g_assert(no_cpu_mutex_locked());
>
>      if (qemu_cpu_is_self(cpu)) {
> -        if (has_bql) {
> -            func(cpu, data);
> +        if (bql) {
> +            if (has_bql) {
> +                func(cpu, data);
> +            } else {
> +                qemu_mutex_lock_iothread();
> +                func(cpu, data);
> +                qemu_mutex_unlock_iothread();
> +            }
>          } else {
> -            qemu_mutex_lock_iothread();
>              func(cpu, data);
> -            qemu_mutex_unlock_iothread();
>          }
>          return;
>      }
> @@ -172,7 +177,7 @@ void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
>      wi.done = false;
>      wi.free = false;
>      wi.exclusive = false;
> -    wi.bql = true;
> +    wi.bql = bql;
>
>      cpu_mutex_lock(cpu);
>      queue_work_on_cpu_locked(cpu, &wi);
> @@ -189,6 +194,17 @@ void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
>      }
>  }
>
> +void run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
> +{
> +    do_run_on_cpu(cpu, func, data, true);
> +}
> +
> +void
> +run_on_cpu_no_bql(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
> +{
> +    do_run_on_cpu(cpu, func, data, false);
> +}
> +
>  void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data)
>  {
>      struct qemu_work_item *wi;


--
Alex Bennée