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SubjectRe: [PATCH 2/2] intel_pstate: Set core to min P state during core offline
On 03/18/2014 10:52 PM, dirk.brandewie@gmail.com wrote:
> From: Dirk Brandewie <dirk.j.brandewie@intel.com>
>
> Change to use ->exit_prepare() callback to do clean up during CPU

->stop()

> hotplug. The requested P state for an offline core will be used by the
> hardware coordination function to select the package P state. If the
> core is under load when it is offlined it will fix the package P state
> floor to the requested P state of offline core.
>
> Reported-by: Patrick Marlier <patrick.marlier@gmail.com>
> Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
> ---
> drivers/cpufreq/intel_pstate.c | 20 +++++++++++++-------
> 1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 2cd36b9..e9092fd 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -447,7 +447,7 @@ static void core_set_pstate(struct cpudata *cpudata, int pstate)
> if (limits.no_turbo)
> val |= (u64)1 << 32;
>
> - wrmsrl(MSR_IA32_PERF_CTL, val);
> + wrmsrl_on_cpu(cpudata->cpu, MSR_IA32_PERF_CTL, val);
> }
>
> static struct cpu_defaults core_params = {
> @@ -773,16 +773,22 @@ static int intel_pstate_verify_policy(struct cpufreq_policy *policy)
> return 0;
> }
>
> -static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
> +static int intel_pstate_cpu_stop(struct cpufreq_policy *policy)
> {
> - int cpu = policy->cpu;
> + int cpu_num = policy->cpu;
> + struct cpudata *cpu = all_cpu_data[cpu_num];
> +
> + pr_info("intel_pstate CPU %d exiting\n", cpu_num);
> +
> + del_timer(&all_cpu_data[cpu_num]->timer);
> + intel_pstate_set_pstate(cpu, cpu->pstate.min_pstate);
> + kfree(all_cpu_data[cpu_num]);
> + all_cpu_data[cpu_num] = NULL;
>

I think it should be relatively simple to keep the intel_pstate_set_pstate()
here inside ->stop() and move the rest of the code to ->exit().

Regards,
Srivatsa S. Bhat

> - del_timer(&all_cpu_data[cpu]->timer);
> - kfree(all_cpu_data[cpu]);
> - all_cpu_data[cpu] = NULL;
> return 0;
> }
>
> +
> static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
> {
> struct cpudata *cpu;
> @@ -818,7 +824,7 @@ static struct cpufreq_driver intel_pstate_driver = {
> .setpolicy = intel_pstate_set_policy,
> .get = intel_pstate_get,
> .init = intel_pstate_cpu_init,
> - .exit = intel_pstate_cpu_exit,
> + .stop = intel_pstate_cpu_stop,
> .name = "intel_pstate",
> };
>



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