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Subject[PATCH v3] cpuidle: haltpoll: Add trace points for guest_halt_poll_ns grow/shrink
Date
Add trace points as are implemented in KVM host halt polling.
This helps tune guest halt polling params.

Signed-off-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com>
---
drivers/cpuidle/governors/haltpoll.c | 15 +++++++++-----
include/trace/events/power.h | 29 ++++++++++++++++++++++++++++
2 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c
index cb2a96eafc02..4c61ff8f460b 100644
--- a/drivers/cpuidle/governors/haltpoll.c
+++ b/drivers/cpuidle/governors/haltpoll.c
@@ -19,6 +19,7 @@
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/kvm_para.h>
+#include <trace/events/power.h>

static unsigned int guest_halt_poll_ns __read_mostly = 200000;
module_param(guest_halt_poll_ns, uint, 0644);
@@ -77,13 +78,16 @@ static int haltpoll_select(struct cpuidle_driver *drv,

static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns)
{
- unsigned int val;
+ unsigned int val, old;

- /* Grow cpu_halt_poll_us if
- * cpu_halt_poll_us < block_ns < guest_halt_poll_us
+ val = dev->poll_limit_ns;
+ old = val;
+
+ /* Grow poll_limit_ns if
+ * poll_limit_ns < block_ns < guest_halt_poll_ns
*/
if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns) {
- val = dev->poll_limit_ns * guest_halt_poll_grow;
+ val *= guest_halt_poll_grow;

if (val < guest_halt_poll_grow_start)
val = guest_halt_poll_grow_start;
@@ -91,16 +95,17 @@ static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns)
val = guest_halt_poll_ns;

dev->poll_limit_ns = val;
+ trace_guest_halt_poll_ns_grow(val, old);
} else if (block_ns > guest_halt_poll_ns &&
guest_halt_poll_allow_shrink) {
unsigned int shrink = guest_halt_poll_shrink;

- val = dev->poll_limit_ns;
if (shrink == 0)
val = 0;
else
val /= shrink;
dev->poll_limit_ns = val;
+ trace_guest_halt_poll_ns_shrink(val, old);
}
}

diff --git a/include/trace/events/power.h b/include/trace/events/power.h
index af5018aa9517..c708521e4ed5 100644
--- a/include/trace/events/power.h
+++ b/include/trace/events/power.h
@@ -500,6 +500,35 @@ DEFINE_EVENT(dev_pm_qos_request, dev_pm_qos_remove_request,

TP_ARGS(name, type, new_value)
);
+
+TRACE_EVENT(guest_halt_poll_ns,
+
+ TP_PROTO(bool grow, unsigned int new, unsigned int old),
+
+ TP_ARGS(grow, new, old),
+
+ TP_STRUCT__entry(
+ __field(bool, grow)
+ __field(unsigned int, new)
+ __field(unsigned int, old)
+ ),
+
+ TP_fast_assign(
+ __entry->grow = grow;
+ __entry->new = new;
+ __entry->old = old;
+ ),
+
+ TP_printk("halt_poll_ns %u (%s %u)",
+ __entry->new,
+ __entry->grow ? "grow" : "shrink",
+ __entry->old)
+);
+
+#define trace_guest_halt_poll_ns_grow(new, old) \
+ trace_guest_halt_poll_ns(true, new, old)
+#define trace_guest_halt_poll_ns_shrink(new, old) \
+ trace_guest_halt_poll_ns(false, new, old)
#endif /* _TRACE_POWER_H */

/* This part must be outside protection */
--
2.36.1
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