Re: [PATCH 5/8] x86/amd: Detect preferred cores in amd_get_boost_ratio_numerator()
From: Mario Limonciello
Date: Tue Aug 27 2024 - 15:01:05 EST
On 8/27/2024 10:43, Gautham R. Shenoy wrote:
On Mon, Aug 26, 2024 at 04:13:55PM -0500, Mario Limonciello wrote:
From: Mario Limonciello <mario.limonciello@xxxxxxx>
AMD systems that support preferred cores will use "166" as their
numerator for max frequency calculations instead of "255".
Add a function for detecting preferred cores by looking at the
highest perf value on all cores.
If preferred cores are enabled return 166 and if disabled the
value in the highest perf register. As the function will be called
multiple times, cache the values for the boost numerator and if
preferred cores will be enabled in global variables.
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
[..snip..]
/**
* amd_get_boost_ratio_numerator: Get the numerator to use for boost ratio calculation
* @cpu: CPU to get numerator for.
@@ -162,20 +232,19 @@ EXPORT_SYMBOL_GPL(amd_get_highest_perf);
*/
int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator)
{
- struct cpuinfo_x86 *c = &boot_cpu_data;
+ bool prefcore;
+ int ret;
- if (c->x86 == 0x17 && ((c->x86_model >= 0x30 && c->x86_model < 0x40) ||
- (c->x86_model >= 0x70 && c->x86_model < 0x80))) {
- *numerator = 166;
- return 0;
- }
+ ret = amd_detect_prefcore(&prefcore);
+ if (ret)
+ return ret;
- if (c->x86 == 0x19 && ((c->x86_model >= 0x20 && c->x86_model < 0x30) ||
- (c->x86_model >= 0x40 && c->x86_model < 0x70))) {
- *numerator = 166;
+ /* without preferred cores, return the highest perf register value */
+ if (!prefcore) {
+ *numerator = boost_numerator;
return 0;
}
- *numerator = 255;
+ *numerator = CPPC_HIGHEST_PERF_PREFCORE;
Interesting. So even when the user boots a system that supports
preferred-cores with "amd_preferred=disable",
amd_get_boost_ratio_numerator() will return CPPC_HIGHEST_PERF_PREFCORE
as the call prefcore == true here.
I suppose that is as intended, since even though the user may not want
to use the preferred core logic for task-scheduling/load-balancing,
the numerator for the boost-ratio is purely dependent on the h/w
capability.
Is this understanding correct? If so, can this be included as a
comment in the code ?
Yup, you got it all right. I'll fold some of this into the function
comment for v2.
The rest of the patch looks good to me.
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>
--
Thanks and Regards
gautham.
return 0;
}
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index f470b5700db58..ec32c830abc1d 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -807,32 +807,18 @@ static DECLARE_WORK(sched_prefcore_work, amd_pstste_sched_prefcore_workfn);
static void amd_pstate_init_prefcore(struct amd_cpudata *cpudata)
{
- int ret, prio;
- u32 highest_perf;
-
- ret = amd_get_highest_perf(cpudata->cpu, &highest_perf);
- if (ret)
+ /* user disabled or not detected */
+ if (!amd_pstate_prefcore)
return;
cpudata->hw_prefcore = true;
- /* check if CPPC preferred core feature is enabled*/
- if (highest_perf < CPPC_MAX_PERF)
- prio = (int)highest_perf;
- else {
- pr_debug("AMD CPPC preferred core is unsupported!\n");
- cpudata->hw_prefcore = false;
- return;
- }
-
- if (!amd_pstate_prefcore)
- return;
/*
* The priorities can be set regardless of whether or not
* sched_set_itmt_support(true) has been called and it is valid to
* update them at any time after it has been called.
*/
- sched_set_itmt_core_prio(prio, cpudata->cpu);
+ sched_set_itmt_core_prio((int)READ_ONCE(cpudata->highest_perf), cpudata->cpu);
schedule_work(&sched_prefcore_work);
}
@@ -998,12 +984,12 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
cpudata->cpu = policy->cpu;
- amd_pstate_init_prefcore(cpudata);
-
ret = amd_pstate_init_perf(cpudata);
if (ret)
goto free_cpudata1;
+ amd_pstate_init_prefcore(cpudata);
+
ret = amd_pstate_init_freq(cpudata);
if (ret)
goto free_cpudata1;
@@ -1453,12 +1439,12 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
cpudata->cpu = policy->cpu;
cpudata->epp_policy = 0;
- amd_pstate_init_prefcore(cpudata);
-
ret = amd_pstate_init_perf(cpudata);
if (ret)
goto free_cpudata1;
+ amd_pstate_init_prefcore(cpudata);
+
ret = amd_pstate_init_freq(cpudata);
if (ret)
goto free_cpudata1;
@@ -1903,6 +1889,12 @@ static int __init amd_pstate_init(void)
static_call_update(amd_pstate_update_perf, cppc_update_perf);
}
+ if (amd_pstate_prefcore) {
+ ret = amd_detect_prefcore(&amd_pstate_prefcore);
+ if (ret)
+ return ret;
+ }
+
/* enable amd pstate feature */
ret = amd_pstate_enable(true);
if (ret) {
diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
index 2246ce0630362..1d79320a23490 100644
--- a/include/acpi/cppc_acpi.h
+++ b/include/acpi/cppc_acpi.h
@@ -137,10 +137,12 @@ struct cppc_cpudata {
};
#ifdef CONFIG_CPU_SUP_AMD
+extern int amd_detect_prefcore(bool *detected);
extern int amd_get_highest_perf(unsigned int cpu, u32 *highest_perf);
extern int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator);
#else /* !CONFIG_CPU_SUP_AMD */
static inline int amd_get_highest_perf(unsigned int cpu, u32 *highest_perf) { return -ENODEV; }
+static inline int amd_detect_prefcore(bool *detected) { return -ENODEV; }
static inline int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator) { return -ENODEV; }
#endif /* !CONFIG_CPU_SUP_AMD */
--
2.43.0