[PATCH 1/3] x86/mce/therm_throt: remove unused platform_thermal_notify function pointer

[PATCH 1/3] x86/mce/therm_throt: remove unused platform_thermal_notify function pointer

[Jason A. Donenfeld]

A long time ago platform_thermal_notify was added as some generic
mechanism for platform drivers to hook thermal events. It seems as
though this has been entirely superseded, and nothing uses it. Remove
the plumbing for this, since this code runs in an interrupt hot path.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/x86/include/asm/mce.h            |  3 ---
 arch/x86/kernel/cpu/mce/therm_throt.c | 25 -------------------------
 2 files changed, 28 deletions(-)

diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index 4359b955e0b7..ee30cb60ad36 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -257,9 +257,6 @@ extern void (*deferred_error_int_vector)(void);
 
 void intel_init_thermal(struct cpuinfo_x86 *c);
 
-/* Interrupt Handler for core thermal thresholds */
-extern int (*platform_thermal_notify)(__u64 msr_val);
-
 /* Interrupt Handler for package thermal thresholds */
 extern int (*platform_thermal_package_notify)(__u64 msr_val);
 
diff --git a/arch/x86/kernel/cpu/mce/therm_throt.c b/arch/x86/kernel/cpu/mce/therm_throt.c
index f36dc0742085..f904e85eb68f 100644
--- a/arch/x86/kernel/cpu/mce/therm_throt.c
+++ b/arch/x86/kernel/cpu/mce/therm_throt.c
@@ -105,10 +105,6 @@ struct thermal_state {
 	struct _thermal_state pkg_thresh1;
 };
 
-/* Callback to handle core threshold interrupts */
-int (*platform_thermal_notify)(__u64 msr_val);
-EXPORT_SYMBOL(platform_thermal_notify);
-
 /* Callback to handle core package threshold_interrupts */
 int (*platform_thermal_package_notify)(__u64 msr_val);
 EXPORT_SYMBOL_GPL(platform_thermal_package_notify);
@@ -551,24 +547,6 @@ static void notify_package_thresholds(__u64 msr_val)
 		platform_thermal_package_notify(msr_val);
 }
 
-static void notify_thresholds(__u64 msr_val)
-{
-	/* check whether the interrupt handler is defined;
-	 * otherwise simply return
-	 */
-	if (!platform_thermal_notify)
-		return;
-
-	/* lower threshold reached */
-	if ((msr_val & THERM_LOG_THRESHOLD0) &&
-			thresh_event_valid(CORE_LEVEL, 0))
-		platform_thermal_notify(msr_val);
-	/* higher threshold reached */
-	if ((msr_val & THERM_LOG_THRESHOLD1) &&
-			thresh_event_valid(CORE_LEVEL, 1))
-		platform_thermal_notify(msr_val);
-}
-
 /* Thermal transition interrupt handler */
 static void intel_thermal_interrupt(void)
 {
@@ -579,9 +557,6 @@ static void intel_thermal_interrupt(void)
 
 	rdmsrl(MSR_IA32_THERM_STATUS, msr_val);
 
-	/* Check for violation of core thermal thresholds*/
-	notify_thresholds(msr_val);
-
 	therm_throt_process(msr_val & THERM_STATUS_PROCHOT,
 			    THERMAL_THROTTLING_EVENT,
 			    CORE_LEVEL);
-- 
2.26.0

[PATCH 2/3] x86/mce/therm_throt: allow disabling verbose logging

[Jason A. Donenfeld]

There is an enormous amount of fiddly book keeping and an auxiliary
workqueue just for the purpose of ratelimiting and reliably printing
messages regarding thermal events and throttling, which uses CPU in a
rather common interrupt. Add an option to disable this verbose
reporting.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/x86/Kconfig                      | 9 +++++++++
 arch/x86/kernel/cpu/mce/therm_throt.c | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index beea77046f9b..39e7444353af 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1159,6 +1159,15 @@ config X86_THERMAL_VECTOR
 	def_bool y
 	depends on X86_MCE_INTEL
 
+config X86_MCE_THERMAL_VERBOSE
+	bool "Verbose logging for thermal events"
+	depends on X86_THERMAL_VECTOR
+	---help---
+	  Display messages in the kernel log when thermal events are triggered,
+	  such as overheating and throttling. This mostly only uses extra CPU
+	  for ratelimiting and book keeping, so unless you need these logs, it
+	  is safe to say N.
+
 source "arch/x86/events/Kconfig"
 
 config X86_LEGACY_VM86
diff --git a/arch/x86/kernel/cpu/mce/therm_throt.c b/arch/x86/kernel/cpu/mce/therm_throt.c
index f904e85eb68f..6d726190a40a 100644
--- a/arch/x86/kernel/cpu/mce/therm_throt.c
+++ b/arch/x86/kernel/cpu/mce/therm_throt.c
@@ -313,6 +313,9 @@ static void therm_throt_process(bool new_event, int event, int level)
 	u64 now;
 	struct thermal_state *pstate = &per_cpu(thermal_state, this_cpu);
 
+	if (!IS_ENABLED(CONFIG_X86_MCE_THERMAL_VERBOSE))
+		return;
+
 	now = get_jiffies_64();
 	if (level == CORE_LEVEL) {
 		if (event == THERMAL_THROTTLING_EVENT)
-- 
2.26.0

[PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Jason A. Donenfeld]

The thermal IRQ handler uses 1.21% CPU on my system when it's hot from
compiling things. Indeed looking at /proc/interrupts reveals quite a lot
of events coming in. Beyond logging them, the existing drivers on the
system don't appear to do very much that I'm interested in. So, add a
way to disable this entirely so that I can regain precious CPU cycles.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/x86/Kconfig                | 4 ++++
 arch/x86/kernel/cpu/mce/intel.c | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 39e7444353af..3125a11932f2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1157,7 +1157,11 @@ config X86_MCE_INJECT
 
 config X86_THERMAL_VECTOR
 	def_bool y
+	prompt "Machine check thermal vector"
 	depends on X86_MCE_INTEL
+	---help---
+	  Provide support for capturing thermal events, logging them, and
+	  passing them off to other drivers.
 
 config X86_MCE_THERMAL_VERBOSE
 	bool "Verbose logging for thermal events"
diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
index f996ffb887bc..d14f1922fb49 100644
--- a/arch/x86/kernel/cpu/mce/intel.c
+++ b/arch/x86/kernel/cpu/mce/intel.c
@@ -511,7 +511,8 @@ static void intel_ppin_init(struct cpuinfo_x86 *c)
 
 void mce_intel_feature_init(struct cpuinfo_x86 *c)
 {
-	intel_init_thermal(c);
+	if (IS_ENABLED(CONFIG_X86_THERMAL_VECTOR))
+		intel_init_thermal(c);
 	intel_init_cmci();
 	intel_init_lmce();
 	intel_ppin_init(c);
-- 
2.26.0

Re: [PATCH 1/3] x86/mce/therm_throt: remove unused platform_thermal_notify function pointer

[Jason A. Donenfeld]

Hi Srinivas & Co,

Could you have a look at this three part series please? Friendly poke.

Jason

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Srinivas Pandruvada]

On Tue, 2020-04-07 at 00:33 -0600, Jason A. Donenfeld wrote:
> The thermal IRQ handler uses 1.21% CPU on my system when it's hot
> from
> compiling things. Indeed looking at /proc/interrupts reveals quite a
> lot
I am curious why you are hitting threshold frequently?
What is rdmsr 0x1a2


> of events coming in. Beyond logging them, the existing drivers on the
> system don't appear to do very much that I'm interested in. So, add a
> way to disable this entirely so that I can regain precious CPU
> cycles.
It is showing amount of time system is running in a constrained
environment. Lots of real time and HPC folks really care about this.

Thanks,
Srinivas

> 
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>  arch/x86/Kconfig                | 4 ++++
>  arch/x86/kernel/cpu/mce/intel.c | 3 ++-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 39e7444353af..3125a11932f2 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1157,7 +1157,11 @@ config X86_MCE_INJECT
>  
>  config X86_THERMAL_VECTOR
>  	def_bool y
> +	prompt "Machine check thermal vector"
>  	depends on X86_MCE_INTEL
> +	---help---
> +	  Provide support for capturing thermal events, logging them,
> and
> +	  passing them off to other drivers.
>  
>  config X86_MCE_THERMAL_VERBOSE
>  	bool "Verbose logging for thermal events"
> diff --git a/arch/x86/kernel/cpu/mce/intel.c
> b/arch/x86/kernel/cpu/mce/intel.c
> index f996ffb887bc..d14f1922fb49 100644
> --- a/arch/x86/kernel/cpu/mce/intel.c
> +++ b/arch/x86/kernel/cpu/mce/intel.c
> @@ -511,7 +511,8 @@ static void intel_ppin_init(struct cpuinfo_x86
> *c)
>  
>  void mce_intel_feature_init(struct cpuinfo_x86 *c)
>  {
> -	intel_init_thermal(c);
> +	if (IS_ENABLED(CONFIG_X86_THERMAL_VECTOR))
> +		intel_init_thermal(c);
>  	intel_init_cmci();
>  	intel_init_lmce();
>  	intel_ppin_init(c);

Re: [PATCH 1/3] x86/mce/therm_throt: remove unused platform_thermal_notify function pointer

[Srinivas Pandruvada]

On Tue, 2020-04-07 at 00:33 -0600, Jason A. Donenfeld wrote:
> A long time ago platform_thermal_notify was added as some generic
> mechanism for platform drivers to hook thermal events. It seems as
> though this has been entirely superseded, and nothing uses it. Remove
> the plumbing for this, since this code runs in an interrupt hot path.
Good idea.

Thanks,
Srinivas

> 
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>  arch/x86/include/asm/mce.h            |  3 ---
>  arch/x86/kernel/cpu/mce/therm_throt.c | 25 -------------------------
>  2 files changed, 28 deletions(-)
> 
> diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
> index 4359b955e0b7..ee30cb60ad36 100644
> --- a/arch/x86/include/asm/mce.h
> +++ b/arch/x86/include/asm/mce.h
> @@ -257,9 +257,6 @@ extern void (*deferred_error_int_vector)(void);
>  
>  void intel_init_thermal(struct cpuinfo_x86 *c);
>  
> -/* Interrupt Handler for core thermal thresholds */
> -extern int (*platform_thermal_notify)(__u64 msr_val);
> -
>  /* Interrupt Handler for package thermal thresholds */
>  extern int (*platform_thermal_package_notify)(__u64 msr_val);
>  
> diff --git a/arch/x86/kernel/cpu/mce/therm_throt.c
> b/arch/x86/kernel/cpu/mce/therm_throt.c
> index f36dc0742085..f904e85eb68f 100644
> --- a/arch/x86/kernel/cpu/mce/therm_throt.c
> +++ b/arch/x86/kernel/cpu/mce/therm_throt.c
> @@ -105,10 +105,6 @@ struct thermal_state {
>  	struct _thermal_state pkg_thresh1;
>  };
>  
> -/* Callback to handle core threshold interrupts */
> -int (*platform_thermal_notify)(__u64 msr_val);
> -EXPORT_SYMBOL(platform_thermal_notify);
> -
>  /* Callback to handle core package threshold_interrupts */
>  int (*platform_thermal_package_notify)(__u64 msr_val);
>  EXPORT_SYMBOL_GPL(platform_thermal_package_notify);
> @@ -551,24 +547,6 @@ static void notify_package_thresholds(__u64
> msr_val)
>  		platform_thermal_package_notify(msr_val);
>  }
>  
> -static void notify_thresholds(__u64 msr_val)
> -{
> -	/* check whether the interrupt handler is defined;
> -	 * otherwise simply return
> -	 */
> -	if (!platform_thermal_notify)
> -		return;
> -
> -	/* lower threshold reached */
> -	if ((msr_val & THERM_LOG_THRESHOLD0) &&
> -			thresh_event_valid(CORE_LEVEL, 0))
> -		platform_thermal_notify(msr_val);
> -	/* higher threshold reached */
> -	if ((msr_val & THERM_LOG_THRESHOLD1) &&
> -			thresh_event_valid(CORE_LEVEL, 1))
> -		platform_thermal_notify(msr_val);
> -}
> -
>  /* Thermal transition interrupt handler */
>  static void intel_thermal_interrupt(void)
>  {
> @@ -579,9 +557,6 @@ static void intel_thermal_interrupt(void)
>  
>  	rdmsrl(MSR_IA32_THERM_STATUS, msr_val);
>  
> -	/* Check for violation of core thermal thresholds*/
> -	notify_thresholds(msr_val);
> -
>  	therm_throt_process(msr_val & THERM_STATUS_PROCHOT,
>  			    THERMAL_THROTTLING_EVENT,
>  			    CORE_LEVEL);

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Jason A. Donenfeld]

On Mon, Apr 13, 2020 at 9:38 PM Srinivas Pandruvada
<srinivas.pandruvada@linux.intel.com> wrote:
>
> On Tue, 2020-04-07 at 00:33 -0600, Jason A. Donenfeld wrote:
> > The thermal IRQ handler uses 1.21% CPU on my system when it's hot
> > from
> > compiling things. Indeed looking at /proc/interrupts reveals quite a
> > lot
> I am curious why you are hitting threshold frequently?
> What is rdmsr 0x1a2

5640000

> > of events coming in. Beyond logging them, the existing drivers on the
> > system don't appear to do very much that I'm interested in. So, add a
> > way to disable this entirely so that I can regain precious CPU
> > cycles.
> It is showing amount of time system is running in a constrained
> environment. Lots of real time and HPC folks really care about this.

Which is why this patch adds an option, not a full removal or
something. Real time and HPC people can keep their expensive
interrupt. Other people with different varieties of system can disable
it.

Re: [PATCH 1/3] x86/mce/therm_throt: remove unused platform_thermal_notify function pointer

[Jason A. Donenfeld]

On Mon, Apr 13, 2020 at 9:56 PM Srinivas Pandruvada
<srinivas.pandruvada@linux.intel.com> wrote:
>
> On Tue, 2020-04-07 at 00:33 -0600, Jason A. Donenfeld wrote:
> > A long time ago platform_thermal_notify was added as some generic
> > mechanism for platform drivers to hook thermal events. It seems as
> > though this has been entirely superseded, and nothing uses it. Remove
> > the plumbing for this, since this code runs in an interrupt hot path.
> Good idea.

Will you take this into your tree? If not, how do your thermal patches
usually go in? A reviewed-by might be useful in that case.

Jason

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Srinivas Pandruvada]

On Mon, 2020-04-13 at 22:21 -0600, Jason A. Donenfeld wrote:
> On Mon, Apr 13, 2020 at 9:38 PM Srinivas Pandruvada
> <srinivas.pandruvada@linux.intel.com> wrote:
> > On Tue, 2020-04-07 at 00:33 -0600, Jason A. Donenfeld wrote:
> > > The thermal IRQ handler uses 1.21% CPU on my system when it's hot
> > > from
> > > compiling things. Indeed looking at /proc/interrupts reveals
> > > quite a
> > > lot
> > I am curious why you are hitting threshold frequently?
> > What is rdmsr 0x1a2
> 
> 5640000
You are getting too many interrupts at 95C. You should look at your
cooling system. 

> 
> > > of events coming in. Beyond logging them, the existing drivers on
> > > the
> > > system don't appear to do very much that I'm interested in. So,
> > > add a
> > > way to disable this entirely so that I can regain precious CPU
> > > cycles.
> > It is showing amount of time system is running in a constrained
> > environment. Lots of real time and HPC folks really care about
> > this.
> 
> Which is why this patch adds an option, not a full removal or
> something. Real time and HPC people can keep their expensive
> interrupt. Other people with different varieties of system
> disable
> it.
Generally compile time flag is not desirable. If it is what required
then we should have boot time flag something in lines of existing
"int_pln_enable" option.

Thanks,
Srinivas

Re: [PATCH 1/3] x86/mce/therm_throt: remove unused platform_thermal_notify function pointer

[Srinivas Pandruvada]

On Mon, 2020-04-13 at 22:21 -0600, Jason A. Donenfeld wrote:
> On Mon, Apr 13, 2020 at 9:56 PM Srinivas Pandruvada
> <srinivas.pandruvada@linux.intel.com> wrote:
> > On Tue, 2020-04-07 at 00:33 -0600, Jason A. Donenfeld wrote:
> > > A long time ago platform_thermal_notify was added as some generic
> > > mechanism for platform drivers to hook thermal events. It seems
> > > as
> > > though this has been entirely superseded, and nothing uses it.
> > > Remove
> > > the plumbing for this, since this code runs in an interrupt hot
> > > path.
> > Good idea.
> 
> Will you take this into your tree?
I am not the maintainer of this tree. So I don't decide this. I can
just give my opinion.

>  If not, how do your thermal patches
> usually go in? A reviewed-by might be useful in that case.
For this patch:

Reviewed-by: Pandruvada, Srinivas <srinivas.pandruvada@linux.intel.com>

> 
> Jason

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Jason A. Donenfeld]

On Tue, Apr 14, 2020 at 8:45 AM Srinivas Pandruvada
<srinivas.pandruvada@linux.intel.com> wrote:
>
> On Mon, 2020-04-13 at 22:21 -0600, Jason A. Donenfeld wrote:
> > On Mon, Apr 13, 2020 at 9:38 PM Srinivas Pandruvada
> > <srinivas.pandruvada@linux.intel.com> wrote:
> > > On Tue, 2020-04-07 at 00:33 -0600, Jason A. Donenfeld wrote:
> > > > The thermal IRQ handler uses 1.21% CPU on my system when it's hot
> > > > from
> > > > compiling things. Indeed looking at /proc/interrupts reveals
> > > > quite a
> > > > lot
> > > I am curious why you are hitting threshold frequently?
> > > What is rdmsr 0x1a2
> >
> > 5640000
> You are getting too many interrupts at 95C. You should look at your
> cooling system.
>
> >
> > > > of events coming in. Beyond logging them, the existing drivers on
> > > > the
> > > > system don't appear to do very much that I'm interested in. So,
> > > > add a
> > > > way to disable this entirely so that I can regain precious CPU
> > > > cycles.
> > > It is showing amount of time system is running in a constrained
> > > environment. Lots of real time and HPC folks really care about
> > > this.
> >
> > Which is why this patch adds an option, not a full removal or
> > something. Real time and HPC people can keep their expensive
> > interrupt. Other people with different varieties of system
> > disable
> > it.
> Generally compile time flag is not desirable. If it is what required
> then we should have boot time flag something in lines of existing
> "int_pln_enable" option.

Generally it is desirable, and extremely common too. This thermal code
-- which mostly functions to print some messages into kmsg -- is very
verbose. This is not something I want to compile into smaller systems.
This is the reason why kconfig has options in the first place. I'm not
sure yet-another boottime flag makes sense for this.

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Srinivas Pandruvada]

On Tue, 2020-04-14 at 13:41 -0600, Jason A. Donenfeld wrote:
> On Tue, Apr 14, 2020 at 8:45 AM Srinivas Pandruvada
> <srinivas.pandruvada@linux.intel.com> wrote:
> > On Mon, 2020-04-13 at 22:21 -0600, Jason A. Donenfeld wrote:
> > > On Mon, Apr 13, 2020 at 9:38 PM Srinivas Pandruvada
> > > <srinivas.pandruvada@linux.intel.com> wrote:
> > > > On Tue, 2020-04-07 at 00:33 -0600, Jason A. Donenfeld wrote:
> > > > > The thermal IRQ handler uses 1.21% CPU on my system when it's
> > > > > hot
> > > > > from
> > > > > compiling things. Indeed looking at /proc/interrupts reveals
> > > > > quite a
> > > > > lot
> > > > I am curious why you are hitting threshold frequently?
> > > > What is rdmsr 0x1a2
> > > 
> > > 5640000
> > You are getting too many interrupts at 95C. You should look at your
> > cooling system.
> > 
> > > > > of events coming in. Beyond logging them, the existing
> > > > > drivers on
> > > > > the
> > > > > system don't appear to do very much that I'm interested in.
> > > > > So,
> > > > > add a
> > > > > way to disable this entirely so that I can regain precious
> > > > > CPU
> > > > > cycles.
> > > > It is showing amount of time system is running in a constrained
> > > > environment. Lots of real time and HPC folks really care about
> > > > this.
> > > 
> > > Which is why this patch adds an option, not a full removal or
> > > something. Real time and HPC people can keep their expensive
> > > interrupt. Other people with different varieties of system
> > > disable
> > > it.
> > Generally compile time flag is not desirable. If it is what
> > required
> > then we should have boot time flag something in lines of existing
> > "int_pln_enable" option.
> 
> Generally it is desirable, and extremely common too. This thermal
> code
> -- which mostly functions to print some messages into kmsg -- is very
> verbose. This is not something I want to compile into smaller
> systems.
> This is the reason why kconfig has options in the first place. I'm
> not
> sure yet-another boottime flag makes sense for this.

Can you send log which is still showing verbose prints with the latest
kernel? I can see interrupts will still fire.

If it is, then temperature trend is still above 95C and cooling systems
is not in control. In another window, print in loop (with sleep 1)
/sys/class/thermal/thermal_zone*/temp
for the zone for which "type == x86_pkg_temp"

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Jason A. Donenfeld]

On Tue, Apr 14, 2020 at 1:58 PM Srinivas Pandruvada
<srinivas.pandruvada@linux.intel.com> wrote:
>
> On Tue, 2020-04-14 at 13:41 -0600, Jason A. Donenfeld wrote:
> > On Tue, Apr 14, 2020 at 8:45 AM Srinivas Pandruvada
> > <srinivas.pandruvada@linux.intel.com> wrote:
> > > On Mon, 2020-04-13 at 22:21 -0600, Jason A. Donenfeld wrote:
> > > > On Mon, Apr 13, 2020 at 9:38 PM Srinivas Pandruvada
> > > > <srinivas.pandruvada@linux.intel.com> wrote:
> > > > > On Tue, 2020-04-07 at 00:33 -0600, Jason A. Donenfeld wrote:
> > > > > > The thermal IRQ handler uses 1.21% CPU on my system when it's
> > > > > > hot
> > > > > > from
> > > > > > compiling things. Indeed looking at /proc/interrupts reveals
> > > > > > quite a
> > > > > > lot
> > > > > I am curious why you are hitting threshold frequently?
> > > > > What is rdmsr 0x1a2
> > > >
> > > > 5640000
> > > You are getting too many interrupts at 95C. You should look at your
> > > cooling system.
> > >
> > > > > > of events coming in. Beyond logging them, the existing
> > > > > > drivers on
> > > > > > the
> > > > > > system don't appear to do very much that I'm interested in.
> > > > > > So,
> > > > > > add a
> > > > > > way to disable this entirely so that I can regain precious
> > > > > > CPU
> > > > > > cycles.
> > > > > It is showing amount of time system is running in a constrained
> > > > > environment. Lots of real time and HPC folks really care about
> > > > > this.
> > > >
> > > > Which is why this patch adds an option, not a full removal or
> > > > something. Real time and HPC people can keep their expensive
> > > > interrupt. Other people with different varieties of system
> > > > disable
> > > > it.
> > > Generally compile time flag is not desirable. If it is what
> > > required
> > > then we should have boot time flag something in lines of existing
> > > "int_pln_enable" option.
> >
> > Generally it is desirable, and extremely common too. This thermal
> > code
> > -- which mostly functions to print some messages into kmsg -- is very
> > verbose. This is not something I want to compile into smaller
> > systems.
> > This is the reason why kconfig has options in the first place. I'm
> > not
> > sure yet-another boottime flag makes sense for this.
>
> Can you send log which is still showing verbose prints with the latest
> kernel? I can see interrupts will still fire.
>
> If it is, then temperature trend is still above 95C and cooling systems
> is not in control. In another window, print in loop (with sleep 1)
> /sys/class/thermal/thermal_zone*/temp
> for the zone for which "type == x86_pkg_temp"

It sounds like you're interested in debugging the cooling system of my
[brand new Thinkpad P1 gen 2] laptop. I appreciate the concern, but
that's really not the purpose of this patch. The purpose of this patch
is to enable disabling the sizable thermal interrupt code, that does
absolutely nothing for a wide variety of systems that do not want that
code in their kernel. In other words, I don't think the particular
thinkpad cooling aspects have anything to do with the need to add the
trivial Kconfig option to not compile this code. I realize it's your
code and you might really like it, but that doesn't mean everyone
wants it in their kernel image.

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Borislav Petkov]

+ Tony.

On Tue, Apr 14, 2020 at 01:41:08PM -0600, Jason A. Donenfeld wrote:
> Generally it is desirable, and extremely common too. This thermal code
> -- which mostly functions to print some messages into kmsg -- is very
> verbose. This is not something I want to compile into smaller systems.
> This is the reason why kconfig has options in the first place. I'm not
> sure yet-another boottime flag makes sense for this.

I don't mind making the already existing option selectable and leaving
it default y, i.e., keeping the current situation by default. And people
who want to disable it, can then do so.

I do mind to having yet another config option though. No thanks -
they're already too many.

So it should be an all or nothing thing.

Poking quickly at that and drivers/thermal/intel/x86_pkg_temp_thermal.c,
all those things do is report trip points. therm_throt reports how long
the hw throttled due to hitting a trip point, etc.

IINM, of course so please correct me if I'm missing anything.

But if not and this all is only for reporting and doesn't have any
detrimental effects on the hardware when missing from the system, then I
guess we could make CONFIG_X86_THERMAL_VECTOR user-selectable.

Thx.

-- 
Regards/Gruss,
    Boris.

SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Srinivas Pandruvada]

On Tue, 2020-04-14 at 22:23 +0200, Borislav Petkov wrote:
> + Tony.
> 
> On Tue, Apr 14, 2020 at 01:41:08PM -0600, Jason A. Donenfeld wrote:
> > Generally it is desirable, and extremely common too. This thermal
> > code
> > -- which mostly functions to print some messages into kmsg -- is
> > very
> > verbose. This is not something I want to compile into smaller
> > systems.
> > This is the reason why kconfig has options in the first place. I'm
> > not
> > sure yet-another boottime flag makes sense for this.
> 
> I don't mind making the already existing option selectable and
> leaving
> it default y, i.e., keeping the current situation by default. And
> people
> who want to disable it, can then do so.
> 
> I do mind to having yet another config option though. No thanks -
> they're already too many.
> 
> So it should be an all or nothing thing.
> 
> Poking quickly at that and
> drivers/thermal/intel/x86_pkg_temp_thermal.c,
> all those things do is report trip points. therm_throt reports how
> long
> the hw throttled due to hitting a trip point, etc.
> 
> IINM, of course so please correct me if I'm missing anything.
> 
> But if not and this all is only for reporting and doesn't have any
> detrimental effects on the hardware when missing from the system,
> then I
> guess we could make CONFIG_X86_THERMAL_VECTOR user-selectable.

We can make user selectable

These drivers are used for reporting only.
User space can select a trip temperature via x86_pkg_temp and get
notification via uevent to start additional cooling system (additional
fans, liquid coooling etc), so that processor don't have to go self
throttling mode. Self throttling depending on processor series and
firmware can be very aggressive.
In client systems thermald will set a temperature and starts power
control once it reaches passive temperature limit. But it can function
without x86_pkg_temp also, so even if user disables thermal reporting
it can still function.
 
Thanks,
Srinivas


> 
> Thx.
> 

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Jason A. Donenfeld]

On Tue, Apr 14, 2020 at 2:49 PM Srinivas Pandruvada
<srinivas.pandruvada@linux.intel.com> wrote:
>
> On Tue, 2020-04-14 at 22:23 +0200, Borislav Petkov wrote:
> > + Tony.
> >
> > On Tue, Apr 14, 2020 at 01:41:08PM -0600, Jason A. Donenfeld wrote:
> > > Generally it is desirable, and extremely common too. This thermal
> > > code
> > > -- which mostly functions to print some messages into kmsg -- is
> > > very
> > > verbose. This is not something I want to compile into smaller
> > > systems.
> > > This is the reason why kconfig has options in the first place. I'm
> > > not
> > > sure yet-another boottime flag makes sense for this.
> >
> > I don't mind making the already existing option selectable and
> > leaving
> > it default y, i.e., keeping the current situation by default. And
> > people
> > who want to disable it, can then do so.
> >
> > I do mind to having yet another config option though. No thanks -
> > they're already too many.
> >
> > So it should be an all or nothing thing.
> >
> > Poking quickly at that and
> > drivers/thermal/intel/x86_pkg_temp_thermal.c,
> > all those things do is report trip points. therm_throt reports how
> > long
> > the hw throttled due to hitting a trip point, etc.
> >
> > IINM, of course so please correct me if I'm missing anything.
> >
> > But if not and this all is only for reporting and doesn't have any
> > detrimental effects on the hardware when missing from the system,
> > then I
> > guess we could make CONFIG_X86_THERMAL_VECTOR user-selectable.
>
> We can make user selectable
>
> These drivers are used for reporting only.
> User space can select a trip temperature via x86_pkg_temp and get
> notification via uevent to start additional cooling system (additional

I didn't see any uevent stuff. Is this part of out-of-tree modules or
proprietary code that's hooking into those EXPORT_SYMBOL (non-GPL)
exports?

> fans, liquid coooling etc), so that processor don't have to go self
> throttling mode. Self throttling depending on processor series and
> firmware can be very aggressive.
> In client systems thermald will set a temperature and starts power
> control once it reaches passive temperature limit. But it can function
> without x86_pkg_temp also, so even if user disables thermal reporting
> it can still function.

The 2/3 patch may be interesting as well to you. This removes the
expensive work queue management stuff if the option is deselected,
since all those workqueues do is print messages to kmsg, while
retaining the rest of the infra.

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Peter Zijlstra]

On Tue, Apr 07, 2020 at 12:33:45AM -0600, Jason A. Donenfeld wrote:
> The thermal IRQ handler uses 1.21% CPU on my system when it's hot from
> compiling things. Indeed looking at /proc/interrupts reveals quite a lot
> of events coming in. Beyond logging them, the existing drivers on the
> system don't appear to do very much that I'm interested in. So, add a
> way to disable this entirely so that I can regain precious CPU cycles.

Why is this MCE code?!? hysterical raisins?

Anyway, I wonder if this is something we should hook up to
SCHED_THERMAL_PRESSURE, Rafael?

> diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
> index f996ffb887bc..d14f1922fb49 100644
> --- a/arch/x86/kernel/cpu/mce/intel.c
> +++ b/arch/x86/kernel/cpu/mce/intel.c
> @@ -511,7 +511,8 @@ static void intel_ppin_init(struct cpuinfo_x86 *c)
>  
>  void mce_intel_feature_init(struct cpuinfo_x86 *c)
>  {
> -	intel_init_thermal(c);
> +	if (IS_ENABLED(CONFIG_X86_THERMAL_VECTOR))
> +		intel_init_thermal(c);
>  	intel_init_cmci();
>  	intel_init_lmce();
>  	intel_ppin_init(c);
> -- 
> 2.26.0
> 

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Srinivas Pandruvada]

On Tue, 2020-04-14 at 23:40 +0200, Peter Zijlstra wrote:
> On Tue, Apr 07, 2020 at 12:33:45AM -0600, Jason A. Donenfeld wrote:
> > The thermal IRQ handler uses 1.21% CPU on my system when it's hot
> > from
> > compiling things. Indeed looking at /proc/interrupts reveals quite
> > a lot
> > of events coming in. Beyond logging them, the existing drivers on
> > the
> > system don't appear to do very much that I'm interested in. So, add
> > a
> > way to disable this entirely so that I can regain precious CPU
> > cycles.
> 
> Why is this MCE code?!? hysterical raisins?
When this code was developed long time ago, it was also doing mce
logging. But it is no longer doing mce logging, but code is still
there.


> 
> Anyway, I wonder if this is something we should hook up to
> SCHED_THERMAL_PRESSURE, Rafael?
> 
> > diff --git a/arch/x86/kernel/cpu/mce/intel.c
> > b/arch/x86/kernel/cpu/mce/intel.c
> > index f996ffb887bc..d14f1922fb49 100644
> > --- a/arch/x86/kernel/cpu/mce/intel.c
> > +++ b/arch/x86/kernel/cpu/mce/intel.c
> > @@ -511,7 +511,8 @@ static void intel_ppin_init(struct cpuinfo_x86
> > *c)
> >  
> >  void mce_intel_feature_init(struct cpuinfo_x86 *c)
> >  {
> > -	intel_init_thermal(c);
> > +	if (IS_ENABLED(CONFIG_X86_THERMAL_VECTOR))
> > +		intel_init_thermal(c);
> >  	intel_init_cmci();
> >  	intel_init_lmce();
> >  	intel_ppin_init(c);
> > -- 
> > 2.26.0
> > 

Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

[Srinivas Pandruvada]

On Tue, 2020-04-14 at 15:07 -0600, Jason A. Donenfeld wrote:
> On Tue, Apr 14, 2020 at 2:49 PM Srinivas Pandruvada
> <srinivas.pandruvada@linux.intel.com> wrote:
> > On Tue, 2020-04-14 at 22:23 +0200, Borislav Petkov wrote:
> > > + Tony.
> > > 
> > > On Tue, Apr 14, 2020 at 01:41:08PM -0600, Jason A. Donenfeld
> > > wrote:
> > > > Generally it is desirable, and extremely common too. This
> > > > thermal
> > > > code
> > > > -- which mostly functions to print some messages into kmsg --
> > > > is
> > > > very
> > > > verbose. This is not something I want to compile into smaller
> > > > systems.
> > > > This is the reason why kconfig has options in the first place.
> > > > I'm
> > > > not
> > > > sure yet-another boottime flag makes sense for this.
> > > 
> > > I don't mind making the already existing option selectable and
> > > leaving
> > > it default y, i.e., keeping the current situation by default. And
> > > people
> > > who want to disable it, can then do so.
> > > 
> > > I do mind to having yet another config option though. No thanks -
> > > they're already too many.
> > > 
> > > So it should be an all or nothing thing.
> > > 
> > > Poking quickly at that and
> > > drivers/thermal/intel/x86_pkg_temp_thermal.c,
> > > all those things do is report trip points. therm_throt reports
> > > how
> > > long
> > > the hw throttled due to hitting a trip point, etc.
> > > 
> > > IINM, of course so please correct me if I'm missing anything.
> > > 
> > > But if not and this all is only for reporting and doesn't have
> > > any
> > > detrimental effects on the hardware when missing from the system,
> > > then I
> > > guess we could make CONFIG_X86_THERMAL_VECTOR user-selectable.
> > 
> > We can make user selectable
> > 
> > These drivers are used for reporting only.
> > User space can select a trip temperature via x86_pkg_temp and get
> > notification via uevent to start additional cooling system
> > (additional
> 
> I didn't see any uevent stuff. Is this part of out-of-tree modules or
> proprietary code that's hooking into those EXPORT_SYMBOL (non-GPL)
> exports?
This is not out of tree. This is x86_pkg_temp driver as part of thermal
subsystem, and thermal_zone_device_update()  user space governor issues uevent. But those are different modifiable thresholds not the high/low temperature thresholds.


> 
> > fans, liquid coooling etc), so that processor don't have to go self
> > throttling mode. Self throttling depending on processor series and
> > firmware can be very aggressive.
> > In client systems thermald will set a temperature and starts power
> > control once it reaches passive temperature limit. But it can
> > function
> > without x86_pkg_temp also, so even if user disables thermal
> > reporting
> > it can still function.
> 
> The 2/3 patch may be interesting as well to you. This removes the
> expensive work queue management stuff if the option is deselected,
> since all those workqueues do is print messages to kmsg, while
> retaining the rest of the infra.