[PATCH v2] cpuidle: haltpoll: Add trace points for guest_halt_poll_ns grow/shrink

Eiichi Tsukata posted 1 patch 1 month ago
drivers/cpuidle/governors/haltpoll.c | 15 ++++++++-----
include/trace/events/power.h         | 33 ++++++++++++++++++++++++++++
2 files changed, 43 insertions(+), 5 deletions(-)
[PATCH v2] cpuidle: haltpoll: Add trace points for guest_halt_poll_ns grow/shrink
Posted by Eiichi Tsukata 1 month ago
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         | 33 ++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c
index cb2a96eafc02..a5b6ad32956c 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(smp_processor_id(), 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(smp_processor_id(), val, old);
 	}
 }
 
diff --git a/include/trace/events/power.h b/include/trace/events/power.h
index af5018aa9517..db065af9c3c0 100644
--- a/include/trace/events/power.h
+++ b/include/trace/events/power.h
@@ -500,6 +500,39 @@ 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 cpu_id,
+		 unsigned int new, unsigned int old),
+
+	TP_ARGS(grow, cpu_id, new, old),
+
+	TP_STRUCT__entry(
+		__field(bool, grow)
+		__field(unsigned int, cpu_id)
+		__field(unsigned int, new)
+		__field(unsigned int, old)
+	),
+
+	TP_fast_assign(
+		__entry->grow   = grow;
+		__entry->cpu_id = cpu_id;
+		__entry->new    = new;
+		__entry->old    = old;
+	),
+
+	TP_printk("cpu %u: halt_poll_ns %u (%s %u)",
+		__entry->cpu_id,
+		__entry->new,
+		__entry->grow ? "grow" : "shrink",
+		__entry->old)
+);
+
+#define trace_guest_halt_poll_ns_grow(cpu_id, new, old) \
+	trace_guest_halt_poll_ns(true, cpu_id, new, old)
+#define trace_guest_halt_poll_ns_shrink(cpu_id, new, old) \
+	trace_guest_halt_poll_ns(false, cpu_id, new, old)
 #endif /* _TRACE_POWER_H */
 
 /* This part must be outside protection */
-- 
2.36.1
Re: [PATCH v2] cpuidle: haltpoll: Add trace points for guest_halt_poll_ns grow/shrink
Posted by Marcelo Tosatti 1 month ago
On Mon, May 23, 2022 at 11:53:32PM +0000, Eiichi Tsukata wrote:
> 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         | 33 ++++++++++++++++++++++++++++
>  2 files changed, 43 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c
> index cb2a96eafc02..a5b6ad32956c 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;
>  

Can do it before the assignment:

		trace_guest_halt_poll_ns_grow(val, dev->poll_limit_ns);

>  		dev->poll_limit_ns = val;
> +		trace_guest_halt_poll_ns_grow(smp_processor_id(), 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(smp_processor_id(), val, old);
>  	}
>  }
>  
> diff --git a/include/trace/events/power.h b/include/trace/events/power.h
> index af5018aa9517..db065af9c3c0 100644
> --- a/include/trace/events/power.h
> +++ b/include/trace/events/power.h
> @@ -500,6 +500,39 @@ 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 cpu_id,
> +		 unsigned int new, unsigned int old),
> +
> +	TP_ARGS(grow, cpu_id, new, old),
> +
> +	TP_STRUCT__entry(
> +		__field(bool, grow)
> +		__field(unsigned int, cpu_id)
> +		__field(unsigned int, new)
> +		__field(unsigned int, old)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->grow   = grow;
> +		__entry->cpu_id = cpu_id;
> +		__entry->new    = new;
> +		__entry->old    = old;
> +	),
> +
> +	TP_printk("cpu %u: halt_poll_ns %u (%s %u)",
> +		__entry->cpu_id,
> +		__entry->new,
> +		__entry->grow ? "grow" : "shrink",
> +		__entry->old)
> +);
> +
> +#define trace_guest_halt_poll_ns_grow(cpu_id, new, old) \
> +	trace_guest_halt_poll_ns(true, cpu_id, new, old)
> +#define trace_guest_halt_poll_ns_shrink(cpu_id, new, old) \
> +	trace_guest_halt_poll_ns(false, cpu_id, new, old)
>  #endif /* _TRACE_POWER_H */
>  
>  /* This part must be outside protection */
> -- 
> 2.36.1
> 
>
Re: [PATCH v2] cpuidle: haltpoll: Add trace points for guest_halt_poll_ns grow/shrink
Posted by Eiichi Tsukata 1 month ago
Hi Marcelo

> On May 26, 2022, at 2:31, Marcelo Tosatti <mtosatti@redhat.com> wrote:
> 
> On Mon, May 23, 2022 at 11:53:32PM +0000, Eiichi Tsukata wrote:
>> 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         | 33 ++++++++++++++++++++++++++++
>> 2 files changed, 43 insertions(+), 5 deletions(-)
>> 
>> diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c
>> index cb2a96eafc02..a5b6ad32956c 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;
>> 
> 
> Can do it before the assignment:
> 
> 		trace_guest_halt_poll_ns_grow(val, dev->poll_limit_ns);


Sure. Will fix it in v4.
Thanks

Eiichi
Re: [PATCH v2] cpuidle: haltpoll: Add trace points for guest_halt_poll_ns grow/shrink
Posted by Steven Rostedt 1 month ago
On Mon, 23 May 2022 23:53:32 +0000
Eiichi Tsukata <eiichi.tsukata@nutanix.com> wrote:

> @@ -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(smp_processor_id(), val, old);

Why are you passing in smp_processor_id()?

>  	} 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(smp_processor_id(), val, old);
>  	}
>  }
>  
> diff --git a/include/trace/events/power.h b/include/trace/events/power.h
> index af5018aa9517..db065af9c3c0 100644
> --- a/include/trace/events/power.h
> +++ b/include/trace/events/power.h
> @@ -500,6 +500,39 @@ 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 cpu_id,
> +		 unsigned int new, unsigned int old),
> +
> +	TP_ARGS(grow, cpu_id, new, old),
> +
> +	TP_STRUCT__entry(
> +		__field(bool, grow)
> +		__field(unsigned int, cpu_id)
> +		__field(unsigned int, new)
> +		__field(unsigned int, old)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->grow   = grow;
> +		__entry->cpu_id = cpu_id;

You are wasting space to save the cpu_id, as the trace event already knows
what CPU it occurred on.

 # echo 1 > events/sched/enable
 # cat trace
#           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
#              | |         |   |||||     |         |
         systemd-1       [004] .....    15.872715: ftrace_boot_snapshot: ** Boot snapshot taken **
         systemd-1       [001] .....    22.555418: initcall_start: func=fuse_len_args+0x0/0x30 [fuse]
         systemd-1       [001] .....    22.555425: initcall_finish: func=fuse_len_args+0x0/0x30 [fuse] ret=0
        modprobe-643     [006] .....    26.737355: initcall_start: func=wmidev_evaluate_method+0x46/0x100 [wmi]
        modprobe-643     [006] .....    26.742491: initcall_finish: func=wmidev_evaluate_method+0x46/0x100 [wmi] ret=0

-- Steve



> +		__entry->new    = new;
> +		__entry->old    = old;
> +	),
> +
> +	TP_printk("cpu %u: halt_poll_ns %u (%s %u)",
> +		__entry->cpu_id,
> +		__entry->new,
> +		__entry->grow ? "grow" : "shrink",
> +		__entry->old)
> +);
> +
Re: [PATCH v2] cpuidle: haltpoll: Add trace points for guest_halt_poll_ns grow/shrink
Posted by Eiichi Tsukata 1 month ago
Hi Steven

> On May 26, 2022, at 1:02, Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> On Mon, 23 May 2022 23:53:32 +0000
> Eiichi Tsukata <eiichi.tsukata@nutanix.com> wrote:
> 
>> @@ -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(smp_processor_id(), val, old);
> 
> Why are you passing in smp_processor_id()?
> 
>> 	} 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(smp_processor_id(), val, old);
>> 	}
>> }
>> 
>> diff --git a/include/trace/events/power.h b/include/trace/events/power.h
>> index af5018aa9517..db065af9c3c0 100644
>> --- a/include/trace/events/power.h
>> +++ b/include/trace/events/power.h
>> @@ -500,6 +500,39 @@ 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 cpu_id,
>> +		 unsigned int new, unsigned int old),
>> +
>> +	TP_ARGS(grow, cpu_id, new, old),
>> +
>> +	TP_STRUCT__entry(
>> +		__field(bool, grow)
>> +		__field(unsigned int, cpu_id)
>> +		__field(unsigned int, new)
>> +		__field(unsigned int, old)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->grow   = grow;
>> +		__entry->cpu_id = cpu_id;
> 
> You are wasting space to save the cpu_id, as the trace event already knows
> what CPU it occurred on.
> 
> # echo 1 > events/sched/enable
> # cat trace
> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> #              | |         |   |||||     |         |
>         systemd-1       [004] .....    15.872715: ftrace_boot_snapshot: ** Boot snapshot taken **
>         systemd-1       [001] .....    22.555418: initcall_start: func=fuse_len_args+0x0/0x30 [fuse]
>         systemd-1       [001] .....    22.555425: initcall_finish: func=fuse_len_args+0x0/0x30 [fuse] ret=0
>        modprobe-643     [006] .....    26.737355: initcall_start: func=wmidev_evaluate_method+0x46/0x100 [wmi]
>        modprobe-643     [006] .....    26.742491: initcall_finish: func=wmidev_evaluate_method+0x46/0x100 [wmi] ret=0
> 
> -- Steve

Thanks for your suggestion.
I added cpu_id as there is a similar precedent “trace_cpu_idle” but I think we can remove cpu_id.
Will fix it in v3.

Eiichi