linux-kernel - Re: [PATCH] cpuidle: Invert CPUIDLE_FLAG_TIME

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Date:	Mon, 17 Nov 2014 13:53:15 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
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Subject: Re: [PATCH] cpuidle: Invert CPUIDLE_FLAG_TIME_VALID logic

On 11/13/2014 03:56 PM, Lorenzo Pieralisi wrote:
> On Wed, Nov 12, 2014 at 03:03:50PM +0000, Daniel Lezcano wrote:
>> The only place where the time is invalid is when the ACPI_CSTATE_FFH entry
>> method is not set. Otherwise for all the drivers, the time can be correctly
>> measured.
>>
>> Instead of duplicating the CPUIDLE_FLAG_TIME_VALID flag in all the drivers
>> for all the states, just invert the logic by replacing it by the flag
>> CPUIDLE_FLAG_TIME_INVALID, hence we can set this flag only for the acpi idle
>> driver, remove the former flag from all the drivers and invert the logic with
>> this flag in the different governor.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>
> Are we sure that ACPI C1 invalid residency time is *still* an issue after
> we moved the residency accounting to the idle core ?

(Cc'ed linux-acpi@)

Hi x86 guys,

any comment on that ?

Thanks in advance

  -- Daniel

> I have a feeling you can remove this flag entirely, but I will let x86
> guys speak for themselves.

[ ... ]

>> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
>> index 17f9ec5..380b4b4 100644
>> --- a/drivers/acpi/processor_idle.c
>> +++ b/drivers/acpi/processor_idle.c
>> @@ -985,8 +985,8 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
>>                  state->flags = 0;
>>                  switch (cx->type) {
>>                          case ACPI_STATE_C1:
>> -                       if (cx->entry_method == ACPI_CSTATE_FFH)
>> -                               state->flags |= CPUIDLE_FLAG_TIME_VALID;
>> +                       if (cx->entry_method != ACPI_CSTATE_FFH)
>> +                               state->flags |= CPUIDLE_FLAG_TIME_INVALID;

[ ... ]


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