Hi Srinivas,
On Sat, Dec 24 2022, srinivas pandruvada wrote:
> On Fri, 2022-12-23 at 10:10 -0800, srinivas pandruvada wrote:
>> Hi Pratyush,
>>
>> On Thu, 2022-12-22 at 11:39 +0100, Pratyush Yadav wrote:
>> >
>> > Hi Srinivas,
>> >
>> > On Wed, Dec 21 2022, srinivas pandruvada wrote:
>> > > On Wed, 2022-12-21 at 16:52 +0100, Pratyush Yadav wrote:
>> > > > When a processor is brought offline and online again, it is
>> > > > unable to
>> > > > use Turbo mode because the _PSS table does not contain the whole
>> > > > turbo
>> > > > frequency range, but only +1 MHz above the max non-turbo
>> > > > frequency.
>> > > > This
>> > > > causes problems when ACPI processor driver tries to set frequency
>> > > > constraints. See patch 2 for more details.
>> > > >
>> I can reproduce on a Broadwell server platform. But not on a client
>> system with acpi_ppc usage.
>>
>> Need to check what change broke this.
>
> When PPC limits enforcement changed to PM QOS, this broke. Previously
> acpi_processor_get_platform_limit() was not enforcing any limits. It
> was just setting variable. So any update done after
> acpi_register_performance_state() call to pr->performance-
>>states[ppc].core_frequency, was effective.
>
> We don't really need to call
> ret = freq_qos_update_request(&pr->perflib_req,
> pr->performance->states[ppc].core_frequency *
> 1000);
>
> if the PPC is not changed. When PPC is changed, this gets called again,
> so then we can call the above function to update cpufreq limit.
>
> The below change fixed for me.
Right. Should I re-roll my patches with your diff below then? Or do you
think my patches should be good to merge as-is?
>
> diff --git a/drivers/acpi/processor_perflib.c
> b/drivers/acpi/processor_perflib.c
> index 757a98f6d7a2..c6ced89c00dd 100644
> --- a/drivers/acpi/processor_perflib.c
> +++ b/drivers/acpi/processor_perflib.c
> @@ -75,6 +75,11 @@ static int acpi_processor_get_platform_limit(struct
> acpi_processor *pr)
> pr_debug("CPU %d: _PPC is %d - frequency %s limited\n", pr->id,
> (int)ppc, ppc ? "" : "not");
>
> + if (ppc == pr->performance_platform_limit) {
> + pr_debug("CPU %d: _PPC is %d - frequency not
> changed\n", pr->id, ppc);
> + return 0;
> + }
> +
> pr->performance_platform_limit = (int)ppc;
>
> if (ppc >= pr->performance->state_count ||
>
--
Regards,
Pratyush Yadav
Amazon Development Center Germany GmbH
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10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
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