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Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP
From: |
Claudio Fontana |
Subject: |
Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP |
Date: |
Mon, 7 Sep 2020 12:05:58 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 |
Hi Richard,
currently rebasing on top of this one,
just a question, why is the patch not directly using "current_machine"?
Is using MACHINE(qdev_get_machine()) preferrable here?
Thanks,
Claudio
On 9/3/20 11:40 PM, Richard Henderson wrote:
> Do not set parallel_cpus if there is only one cpu instantiated.
> This will allow tcg to use serial code to implement atomics.
>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> softmmu/cpus.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/softmmu/cpus.c b/softmmu/cpus.c
> index a802e899ab..e3b98065c9 100644
> --- a/softmmu/cpus.c
> +++ b/softmmu/cpus.c
> @@ -1895,6 +1895,16 @@ static void qemu_tcg_init_vcpu(CPUState *cpu)
> if (!tcg_region_inited) {
> tcg_region_inited = 1;
> tcg_region_init();
> + /*
> + * If MTTCG, and we will create multiple cpus,
> + * then we will have cpus running in parallel.
> + */
> + if (qemu_tcg_mttcg_enabled()) {
> + MachineState *ms = MACHINE(qdev_get_machine());
MachineState *ms = current_machine;
?
> + if (ms->smp.max_cpus > 1) {
> + parallel_cpus = true;
> + }
> + }
> }
>
> if (qemu_tcg_mttcg_enabled() || !single_tcg_cpu_thread) {
> @@ -1904,7 +1914,6 @@ static void qemu_tcg_init_vcpu(CPUState *cpu)
>
> if (qemu_tcg_mttcg_enabled()) {
> /* create a thread per vCPU with TCG (MTTCG) */
> - parallel_cpus = true;
> snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
> cpu->cpu_index);
>
>
- [PULL 0/5] tcg patch queue, Richard Henderson, 2020/09/03
- [PULL 1/5] cputlb: Make store_helper less fragile to compiler optimizations, Richard Henderson, 2020/09/03
- [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP, Richard Henderson, 2020/09/03
- Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP,
Claudio Fontana <=
- Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP, Philippe Mathieu-Daudé, 2020/09/07
- Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP, Claudio Fontana, 2020/09/07
- Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP, Philippe Mathieu-Daudé, 2020/09/07
- Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP, Claudio Fontana, 2020/09/08
- Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP, Philippe Mathieu-Daudé, 2020/09/08
- Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP, Claudio Fontana, 2020/09/10
- Re: [PULL 3/5] softmmu/cpus: Only set parallel_cpus for SMP, Philippe Mathieu-Daudé, 2020/09/10
[PULL 2/5] tcg: Fix tcg gen for vectorized absolute value, Richard Henderson, 2020/09/03
[PULL 4/5] tcg: Eliminate one store for in-place 128-bit dup_mem, Richard Henderson, 2020/09/03
[PULL 5/5] tcg: Implement 256-bit dup for tcg_gen_gvec_dup_mem, Richard Henderson, 2020/09/03