Messages in this thread Patch in this message | | | Date | Tue, 30 Nov 2021 17:02:12 -0800 | Subject | [PATCH v3 08/13] ACPI: add perf low power callback | From | Stephane Eranian <> |
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This patch add an optional callback needed by some PMU features, e.g., AMD BRS, to give a chance to the perf_events code to change its state before going to low power and after coming back.
The callback is void when the PERF_NEEDS_LOPWR_CB flag is not set. This flag must be set in arch specific perf_event.h header whenever needed. When not set, there is no impact of the ACPI code.
Signed-off-by: Stephane Eranian <eranian@google.com> --- drivers/acpi/acpi_pad.c | 6 ++++++ drivers/acpi/processor_idle.c | 5 +++++ include/linux/perf_event.h | 6 ++++++ 3 files changed, 17 insertions(+)
diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c index f45979aa2d64..a306a07a60b5 100644 --- a/drivers/acpi/acpi_pad.c +++ b/drivers/acpi/acpi_pad.c @@ -164,6 +164,9 @@ static int power_saving_thread(void *data) tsc_marked_unstable = 1; } local_irq_disable(); + + perf_lopwr_cb(true); + tick_broadcast_enable(); tick_broadcast_enter(); stop_critical_timings(); @@ -172,6 +175,9 @@ static int power_saving_thread(void *data) start_critical_timings(); tick_broadcast_exit(); + + perf_lopwr_cb(false); + local_irq_enable(); if (time_before(expire_time, jiffies)) { diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 76ef1bcc8848..7a3a613ae5ed 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -20,6 +20,7 @@ #include <linux/tick.h> #include <linux/cpuidle.h> #include <linux/cpu.h> +#include <linux/perf_event.h> #include <acpi/processor.h> /* @@ -546,6 +547,8 @@ static void wait_for_freeze(void) */ static void __cpuidle acpi_idle_do_entry(struct acpi_processor_cx *cx) { + perf_lopwr_cb(true); + if (cx->entry_method == ACPI_CSTATE_FFH) { /* Call into architectural FFH based C-state */ acpi_processor_ffh_cstate_enter(cx); @@ -556,6 +559,8 @@ static void __cpuidle acpi_idle_do_entry(struct acpi_processor_cx *cx) inb(cx->address); wait_for_freeze(); } + + perf_lopwr_cb(false); } /** diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index bbe02c80244b..f9760873e145 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1674,4 +1674,10 @@ typedef int (perf_snapshot_branch_stack_t)(struct perf_branch_entry *entries, unsigned int cnt); DECLARE_STATIC_CALL(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t); +#ifndef PERF_NEEDS_LOPWR_CB +static inline void perf_lopwr_cb(bool mode) +{ +} +#endif + #endif /* _LINUX_PERF_EVENT_H */ -- 2.34.0.rc2.393.gf8c9666880-goog
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