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| author | Stephane Eranian <eranian@google.com> | 2022-03-22 15:15:12 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-04-05 10:24:38 +0200 |
| commit | 2a606a18cd672a16343d146a126721b34cc6adbd (patch) | |
| tree | de6c1658adb954ac20819332cf1e033fd7cb8cf2 | |
| parent | cc37e520a236069c0de0e7ea455082fa11c73b12 (diff) | |
| download | lwn-2a606a18cd672a16343d146a126721b34cc6adbd.tar.gz lwn-2a606a18cd672a16343d146a126721b34cc6adbd.zip | |
ACPI: Add perf low power callback
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
a CPU goes to low power and after it comes 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 on the ACPI code.
Signed-off-by: Stephane Eranian <eranian@google.com>
[peterz: build fix]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220322221517.2510440-9-eranian@google.com
| -rw-r--r-- | drivers/acpi/acpi_pad.c | 7 | ||||
| -rw-r--r-- | drivers/acpi/processor_idle.c | 5 | ||||
| -rw-r--r-- | include/linux/perf_event.h | 6 |
3 files changed, 18 insertions, 0 deletions
diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c index f45979aa2d64..ec0e22a1e25d 100644 --- a/drivers/acpi/acpi_pad.c +++ b/drivers/acpi/acpi_pad.c @@ -17,6 +17,7 @@ #include <linux/tick.h> #include <linux/slab.h> #include <linux/acpi.h> +#include <linux/perf_event.h> #include <asm/mwait.h> #include <xen/xen.h> @@ -164,6 +165,9 @@ 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 +176,9 @@ 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 32b20efff5f8..05dc0e148f02 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -21,6 +21,7 @@ #include <linux/cpuidle.h> #include <linux/cpu.h> #include <linux/minmax.h> +#include <linux/perf_event.h> #include <acpi/processor.h> /* @@ -549,6 +550,8 @@ 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); @@ -559,6 +562,8 @@ 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 a411080d5169..da759560eec5 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1676,4 +1676,10 @@ 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 */ |