On 12/17/2015 12:45 AM, Seiichi Ikarashi wrote:
> On 2015-12-15 22:02, Prarit Bhargava wrote:
>> The MSR_PKG_POWER_INFO register (Intel ASDM, section 14.9.3
>> "Package RAPL Domain") provides a maximum time window which the
>> system can support. This window is read-only and is currently
>> not examined when setting the time windows for the package.
>
> I have been having a question here long time.
> Maximum Time Window (bits 53:48) in MSR_PKG_POWER_INFO is only
> 6-bit length even though Time Window for Power Limit #1 (bits 23:17)
> and Time Window for Power Limit #2 (bits 55:49) in MSR_PKG_POWER_LIMIT
> are both 7-bit length, not 6.
While looking at the MSR settings I had exactly the same question! I too would
like to know the answer.
>
> Do Intel guys have an answer for it?
>
>
> The patch itself looks good to me.
> Just minor comments below:
>
>> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
>> index cc97f08..f765b2c 100644
>> --- a/drivers/powercap/intel_rapl.c
>> +++ b/drivers/powercap/intel_rapl.c
>> @@ -493,13 +493,42 @@ static int get_current_power_limit(struct
>> powercap_zone *power_zone, int id,
>> return ret;
>> }
>>
>> +static int get_max_time_window(struct powercap_zone *power_zone, int id,
>
> The 2nd arg "id" is not necessary.
I'll drop this in v2.
>
>> + u64 *data)
>> +{
>> + struct rapl_domain *rd;
>> + int ret = 0;
>> + u64 val;
>> +
>> + get_online_cpus();
>> + rd = power_zone_to_rapl_domain(power_zone);
>> +
>> + if (rapl_read_data_raw(rd, MAX_TIME_WINDOW, true, &val))
>
> rapl_read_data_raw() can return -EINVAL and -ENODEV other than -EIO.
>
>> + ret = -EIO;
>
> Is it OK to limit ret to -EIO here?
AFAICT it seems like it. The only error that can occur here (at least by the
time this code is executed) is that there is a range error. -EIO seems
appropriate.
>
>> + else
>> + *data = val;
>> +
>> + put_online_cpus();
>> + return ret;
>> +}
>> +
>> static int set_time_window(struct powercap_zone *power_zone, int id,
>> u64 window)
>> {
>> struct rapl_domain *rd;
>> int ret = 0;
>> + u64 max_window;
>>
>> get_online_cpus();
>> + ret = get_max_time_window(power_zone, id, &max_window);
>> + if (ret < 0)
>> + goto out;
>> +
>> + if (window > max_window) {
>> + ret = -EINVAL;
>> + goto out;
>> + }
>> +
>> rd = power_zone_to_rapl_domain(power_zone);
>> switch (rd->rpl[id].prim_id) {
>> case PL1_ENABLE:
>> @@ -511,6 +540,7 @@ static int set_time_window(struct powercap_zone
>> *power_zone, int id,
>> default:
>> ret = -EINVAL;
>> }
>> +out:
>> put_online_cpus();
>> return ret;
>> }
>> @@ -590,6 +620,7 @@ static struct powercap_zone_constraint_ops
>> constraint_ops = {
>> .set_time_window_us = set_time_window,
>> .get_time_window_us = get_time_window,
>> .get_max_power_uw = get_max_power,
>> + .get_max_time_window_us = get_max_time_window,
>> .get_name = get_constraint_name,
>> };
>>
>> diff --git a/drivers/powercap/powercap_sys.c
>> b/drivers/powercap/powercap_sys.c
>> index 84419af..7d77b83 100644
>> --- a/drivers/powercap/powercap_sys.c
>> +++ b/drivers/powercap/powercap_sys.c
>> @@ -101,7 +101,7 @@ static ssize_t store_constraint_##_attr(struct device
>> *dev,\
>> int err; \
>> u64 value; \
>> struct powercap_zone *power_zone = to_powercap_zone(dev); \
>> - int id; \
>> + int id, ret; \
>> struct powercap_zone_constraint *pconst;\
>> \
>> if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
>> @@ -113,8 +113,10 @@ static ssize_t store_constraint_##_attr(struct device
>> *dev,\
>> if (err) \
>> return -EINVAL; \
>> if (pconst && pconst->ops && pconst->ops->set_##_attr) { \
>> - if (!pconst->ops->set_##_attr(power_zone, id, value)) \
>> + ret = pconst->ops->set_##_attr(power_zone, id, value); \
>> + if (!ret) \
>> return count; \
>> + return ret; \
>
> An opposite question to above.
> Is it OK not to limit the return value to -EINVAL here?
> Do you want this function to return -EIO or something?
In this case, no, because the define is used by other values. I think that
would limit all erros in the set_* functions to be -EIO.
P.
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