On 2014年08月22日 16:33, Lan Tianyu wrote:
> In the current world, all nonboot cpus are enabled serially during system
> resume. System resume sequence is that boot cpu enables nonboot cpu one by
> one and then resume devices. Before resuming devices, there are few tasks
> assigned to nonboot cpus after they are brought up. This waste cpu usage.
>
> To accelerate S3, this patches allows boot cpu to go forward to resume
> devices after bringing up one nonboot cpu. The nonboot cpu will be in
> charge of bringing up other cpus. This makes enabling cpu2~x parallel
> with resuming devices.
>
> Signed-off-by: Lan Tianyu <tianyu....@intel.com>
> ---
> Change since V1:
> Remove PM_PARALLEL_CPU_UP_FOR_SUSPEND kernel config and make
> paralleling cpu as default behaviour. Add error handling for
> failure of the first frozen cpu online.
>
> So far, I just tested the patch on the Intel machines. It's better
> to test it on the others Arch platforms. Appreciate a lot if some
> one can help test it.
>
Hi All:
Any comments on this patch? Thanks.
> kernel/cpu.c | 70
> +++++++++++++++++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 58 insertions(+), 12 deletions(-)
>
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index a343bde..9bc8497 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -551,8 +551,42 @@ void __weak arch_enable_nonboot_cpus_end(void)
> {
> }
>
> +static int _cpu_up_with_trace(int cpu)
> +{
> + int error;
> +
> + trace_suspend_resume(TPS("CPU_ON"), cpu, true);
> + error = _cpu_up(cpu, 1);
> + trace_suspend_resume(TPS("CPU_ON"), cpu, false);
> + if (error) {
> + pr_warn("Error taking CPU%d up: %d\n", cpu, error);
> + return error;
> + }
> +
> + pr_info("CPU%d is up\n", cpu);
> + return 0;
> +}
> +
> +static int async_enable_nonboot_cpus(void *data)
> +{
> + int cpu;
> +
> + cpu_maps_update_begin();
> + arch_enable_nonboot_cpus_begin();
> +
> + for_each_cpu(cpu, frozen_cpus) {
> + _cpu_up_with_trace(cpu);
> + }
> +
> + arch_enable_nonboot_cpus_end();
> + cpumask_clear(frozen_cpus);
> + cpu_maps_update_done();
> + return 0;
> +}
> +
> void __ref enable_nonboot_cpus(void)
> {
> + struct task_struct *tsk;
> int cpu, error;
>
> /* Allow everyone to use the CPU hotplug again */
> @@ -563,22 +597,34 @@ void __ref enable_nonboot_cpus(void)
>
> pr_info("Enabling non-boot CPUs ...\n");
>
> - arch_enable_nonboot_cpus_begin();
> + cpu = cpumask_first(frozen_cpus);
> + cpumask_clear_cpu(cpu, frozen_cpus);
>
> - for_each_cpu(cpu, frozen_cpus) {
> - trace_suspend_resume(TPS("CPU_ON"), cpu, true);
> - error = _cpu_up(cpu, 1);
> - trace_suspend_resume(TPS("CPU_ON"), cpu, false);
> - if (!error) {
> - pr_info("CPU%d is up\n", cpu);
> - continue;
> + error = _cpu_up_with_trace(cpu);
> + if (cpumask_empty(frozen_cpus))
> + goto out;
> +
> + if (error) {
> + /*
> + * If fail to bring up the first frozen cpus,
> + * enable the rest frozen cpus on the boot cpu.
> + */
> + arch_enable_nonboot_cpus_begin();
> + for_each_cpu(cpu, frozen_cpus) {
> + _cpu_up_with_trace(cpu);
> }
> - pr_warn("Error taking CPU%d up: %d\n", cpu, error);
> - }
> + arch_enable_nonboot_cpus_end();
>
> - arch_enable_nonboot_cpus_end();
> + } else {
> + tsk = kthread_create_on_cpu(async_enable_nonboot_cpus,
> + NULL, cpu, "async-enable-nonboot-cpus");
> + if (IS_ERR(tsk)) {
> + pr_err("Failed to create async enable nonboot cpus
> thread.\n");
> + goto out;
> + }
>
> - cpumask_clear(frozen_cpus);
> + kthread_unpark(tsk);
> + }
> out:
> cpu_maps_update_done();
> }
>
--
Best regards
Tianyu Lan
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