The following commit has been merged into the perf/core branch of tip:
Commit-ID: 2a606a18cd672a16343d146a126721b34cc6adbd
Gitweb: https://git.kernel.org/tip/2a606a18cd672a16343d146a126721b34cc6adbd
Author: Stephane Eranian <eranian@xxxxxxxxxx>
AuthorDate: Tue, 22 Mar 2022 15:15:12 -07:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 05 Apr 2022 10:24:38 +02:00
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@xxxxxxxxxx>
[peterz: build fix]
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220322221517.2510440-9-eranian@xxxxxxxxxx
---
drivers/acpi/acpi_pad.c | 7 +++++++
drivers/acpi/processor_idle.c | 5 +++++
include/linux/perf_event.h | 6 ++++++
3 files changed, 18 insertions(+)
diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
index f45979a..ec0e22a 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 32b20ef..05dc0e1 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 a411080..da75956 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 */
|