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Date: Wed, 26 Feb 2014 09:08:46 +0800
From: Lan Tianyu <tianyu.lan@...el.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
CC: tj@...nel.org, jolsa@...hat.com, oleg@...hat.com, lenb@...nel.org,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI/Processor: Rework processor throttling with work_on_cpu()
On 2014年02月26日 09:23, Rafael J. Wysocki wrote:
> On Friday, February 21, 2014 01:35:45 PM Lan Tianyu wrote:
>> acpi_processor_set_throttling() uses set_cpus_allowed_ptr() to make
>> sure struct acpi_processor->acpi_processor_set_throttling() callback
>> run on associated cpu. But the function maybe called in a worker which
>> has been bound to a cpu. The patch is to replace set_cpus_allowed_ptr()
>> with work_on_cpu().
>>
>> Signed-off-by: Lan Tianyu <tianyu.lan@...el.com>
>> ---
>> drivers/acpi/processor_throttling.c | 70 +++++++++++++++++--------------------
>> 1 file changed, 33 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
>> index 28baa05..2db105a 100644
>> --- a/drivers/acpi/processor_throttling.c
>> +++ b/drivers/acpi/processor_throttling.c
>> @@ -56,6 +56,12 @@ struct throttling_tstate {
>> int target_state; /* target T-state */
>> };
>>
>> +struct acpi_processor_throttling_arg {
>> + struct acpi_processor *pr;
>> + int target_state;
>> + bool force;
>> +};
>> +
>> #define THROTTLING_PRECHANGE (1)
>> #define THROTTLING_POSTCHANGE (2)
>>
>> @@ -1060,16 +1066,25 @@ static int acpi_processor_set_throttling_ptc(struct acpi_processor *pr,
>> return 0;
>> }
>>
>> +static long acpi_processor_throttling_fn(void *data)
>> +{
>> + struct acpi_processor_throttling_arg *arg = data;
>> + struct acpi_processor *pr = arg->pr;
>> + struct acpi_processor_throttling *p_throttling = &pr->throttling;
>> +
>> + return p_throttling->acpi_processor_set_throttling(pr,
>> + arg->target_state, arg->force);
>
> What about doing
>
> return pr->throttling.acpi_processor_set_throttling(...);
>
> directly without using the extra p_throttling pointer?
This is better. I will update soon.
>
>> +}
>> +
>> int acpi_processor_set_throttling(struct acpi_processor *pr,
>> int state, bool force)
>> {
>> - cpumask_var_t saved_mask;
>> int ret = 0;
>> unsigned int i;
>> struct acpi_processor *match_pr;
>> struct acpi_processor_throttling *p_throttling;
>> + struct acpi_processor_throttling_arg arg;
>> struct throttling_tstate t_state;
>> - cpumask_var_t online_throttling_cpus;
>>
>> if (!pr)
>> return -EINVAL;
>> @@ -1080,14 +1095,6 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
>> if ((state < 0) || (state > (pr->throttling.state_count - 1)))
>> return -EINVAL;
>>
>> - if (!alloc_cpumask_var(&saved_mask, GFP_KERNEL))
>> - return -ENOMEM;
>> -
>> - if (!alloc_cpumask_var(&online_throttling_cpus, GFP_KERNEL)) {
>> - free_cpumask_var(saved_mask);
>> - return -ENOMEM;
>> - }
>> -
>> if (cpu_is_offline(pr->id)) {
>> /*
>> * the cpu pointed by pr->id is offline. Unnecessary to change
>> @@ -1096,17 +1103,15 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
>> return -ENODEV;
>> }
>>
>> - cpumask_copy(saved_mask, ¤t->cpus_allowed);
>> t_state.target_state = state;
>> p_throttling = &(pr->throttling);
>> - cpumask_and(online_throttling_cpus, cpu_online_mask,
>> - p_throttling->shared_cpu_map);
>> +
>> /*
>> * The throttling notifier will be called for every
>> * affected cpu in order to get one proper T-state.
>> * The notifier event is THROTTLING_PRECHANGE.
>> */
>> - for_each_cpu(i, online_throttling_cpus) {
>> + for_each_cpu_and(i, cpu_online_mask, p_throttling->shared_cpu_map) {
>> t_state.cpu = i;
>> acpi_processor_throttling_notifier(THROTTLING_PRECHANGE,
>> &t_state);
>> @@ -1118,21 +1123,18 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
>> * it can be called only for the cpu pointed by pr.
>> */
>> if (p_throttling->shared_type == DOMAIN_COORD_TYPE_SW_ANY) {
>> - /* FIXME: use work_on_cpu() */
>> - if (set_cpus_allowed_ptr(current, cpumask_of(pr->id))) {
>> - /* Can't migrate to the pr->id CPU. Exit */
>> - ret = -ENODEV;
>> - goto exit;
>> - }
>> - ret = p_throttling->acpi_processor_set_throttling(pr,
>> - t_state.target_state, force);
>> + arg.pr = pr;
>> + arg.target_state = state;
>> + arg.force = force;
>> + ret = work_on_cpu(pr->id, acpi_processor_throttling_fn, &arg);
>> } else {
>> /*
>> * When the T-state coordination is SW_ALL or HW_ALL,
>> * it is necessary to set T-state for every affected
>> * cpus.
>> */
>> - for_each_cpu(i, online_throttling_cpus) {
>> + for_each_cpu_and(i, cpu_online_mask,
>> + p_throttling->shared_cpu_map) {
>> match_pr = per_cpu(processors, i);
>> /*
>> * If the pointer is invalid, we will report the
>> @@ -1153,13 +1155,12 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
>> "on CPU %d\n", i));
>> continue;
>> }
>> - t_state.cpu = i;
>> - /* FIXME: use work_on_cpu() */
>> - if (set_cpus_allowed_ptr(current, cpumask_of(i)))
>> - continue;
>> - ret = match_pr->throttling.
>> - acpi_processor_set_throttling(
>> - match_pr, t_state.target_state, force);
>> +
>> + arg.pr = match_pr;
>> + arg.target_state = state;
>> + arg.force = force;
>> + ret = work_on_cpu(pr->id, acpi_processor_throttling_fn,
>> + &arg);
>> }
>> }
>> /*
>> @@ -1168,17 +1169,12 @@ int acpi_processor_set_throttling(struct acpi_processor *pr,
>> * affected cpu to update the T-states.
>> * The notifier event is THROTTLING_POSTCHANGE
>> */
>> - for_each_cpu(i, online_throttling_cpus) {
>> + for_each_cpu_and(i, cpu_online_mask, p_throttling->shared_cpu_map) {
>> t_state.cpu = i;
>> acpi_processor_throttling_notifier(THROTTLING_POSTCHANGE,
>> &t_state);
>> }
>> - /* restore the previous state */
>> - /* FIXME: use work_on_cpu() */
>> - set_cpus_allowed_ptr(current, saved_mask);
>> -exit:
>> - free_cpumask_var(online_throttling_cpus);
>> - free_cpumask_var(saved_mask);
>> +
>> return ret;
>> }
>>
>>
>
--
Best regards
Tianyu Lan
--
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