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[PATCH] powercap/rapl: reduce ipi calls

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  [PATCH] powercap/rapl: reduce ipi calls Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-12-08 00:10 +0100
    Re: [PATCH] powercap/rapl: reduce ipi calls Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> - 2015-12-08 00:30 +0100
      Re: [PATCH] powercap/rapl: reduce ipi calls Peter Zijlstra <peterz@infradead.org> - 2015-12-08 09:50 +0100

#1286084 — [PATCH] powercap/rapl: reduce ipi calls

Reduce remote CPU calls for MSR access by combining read
modify write into one function.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 drivers/powercap/intel_rapl.c | 91 +++++++++++++++++++++++++++----------------
 1 file changed, 58 insertions(+), 33 deletions(-)

diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
index cc97f08..620c916 100644
--- a/drivers/powercap/intel_rapl.c
+++ b/drivers/powercap/intel_rapl.c
@@ -800,33 +800,43 @@ static int rapl_read_data_raw(struct rapl_domain *rd,
 	return 0;
 }
 
+struct rapl_msr_action {
+	u32 msr;
+	unsigned long long value;
+	int shift;
+	u64 mask;
+};
+
+static void rapl_write_data_cpu(void *info)
+{
+	u64 msr_val;
+	struct rapl_msr_action *ra = (struct rapl_msr_action *)info;
+
+	rdmsrl_safe(ra->msr, &msr_val);
+	msr_val &= ~ra->mask;
+	msr_val |= ra->value << ra->shift;
+	wrmsrl_safe(ra->msr, msr_val);
+}
+
 /* Similar use of primitive info in the read counterpart */
 static int rapl_write_data_raw(struct rapl_domain *rd,
 			enum rapl_primitives prim,
 			unsigned long long value)
 {
-	u64 msr_val;
-	u32 msr;
+
+	struct rapl_msr_action ra;
 	struct rapl_primitive_info *rp = &rpi[prim];
 	int cpu;
 
 	cpu = find_active_cpu_on_package(rd->package_id);
 	if (cpu < 0)
 		return cpu;
-	msr = rd->msrs[rp->id];
-	if (rdmsrl_safe_on_cpu(cpu, msr, &msr_val)) {
-		dev_dbg(&rd->power_zone.dev,
-			"failed to read msr 0x%x on cpu %d\n", msr, cpu);
-		return -EIO;
-	}
-	value = rapl_unit_xlate(rd, rd->package_id, rp->unit, value, 1);
-	msr_val &= ~rp->mask;
-	msr_val |= value << rp->shift;
-	if (wrmsrl_safe_on_cpu(cpu, msr, msr_val)) {
-		dev_dbg(&rd->power_zone.dev,
-			"failed to write msr 0x%x on cpu %d\n", msr, cpu);
-		return -EIO;
-	}
+
+	ra.msr = rd->msrs[rp->id];
+	ra.shift = rp->shift;
+	ra.mask = rp->mask;
+	ra.value = rapl_unit_xlate(rd, rd->package_id, rp->unit, value, 1);
+	smp_call_function_single(cpu, rapl_write_data_cpu, &ra, 1);
 
 	return 0;
 }
@@ -893,6 +903,21 @@ static int rapl_check_unit_atom(struct rapl_package *rp, int cpu)
 	return 0;
 }
 
+static void power_limit_irq_save_cpu(void *info)
+{
+	u32 l, h = 0;
+	struct rapl_package *rp = (struct rapl_package *)info;
+
+	/* save the state of PLN irq mask bit before disabling it */
+	rdmsr_safe(MSR_IA32_PACKAGE_THERM_INTERRUPT, &l, &h);
+	if (!(rp->power_limit_irq & PACKAGE_PLN_INT_SAVED)) {
+		rp->power_limit_irq = l & PACKAGE_THERM_INT_PLN_ENABLE;
+		rp->power_limit_irq |= PACKAGE_PLN_INT_SAVED;
+	}
+	l &= ~PACKAGE_THERM_INT_PLN_ENABLE;
+	wrmsr_safe(MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
+}
+
 
 /* REVISIT:
  * When package power limit is set artificially low by RAPL, LVT
@@ -906,7 +931,6 @@ static int rapl_check_unit_atom(struct rapl_package *rp, int cpu)
 
 static void package_power_limit_irq_save(int package_id)
 {
-	u32 l, h = 0;
 	int cpu;
 	struct rapl_package *rp;
 
@@ -920,20 +944,27 @@ static void package_power_limit_irq_save(int package_id)
 	cpu = find_active_cpu_on_package(package_id);
 	if (cpu < 0)
 		return;
-	/* save the state of PLN irq mask bit before disabling it */
-	rdmsr_safe_on_cpu(cpu, MSR_IA32_PACKAGE_THERM_INTERRUPT, &l, &h);
-	if (!(rp->power_limit_irq & PACKAGE_PLN_INT_SAVED)) {
-		rp->power_limit_irq = l & PACKAGE_THERM_INT_PLN_ENABLE;
-		rp->power_limit_irq |= PACKAGE_PLN_INT_SAVED;
-	}
-	l &= ~PACKAGE_THERM_INT_PLN_ENABLE;
-	wrmsr_on_cpu(cpu, MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
+	smp_call_function_single(cpu, power_limit_irq_save_cpu, rp, 1);
+}
+
+static void power_limit_irq_restore_cpu(void *info)
+{
+	u32 l, h = 0;
+	struct rapl_package *rp = (struct rapl_package *)info;
+
+	rdmsr_safe(MSR_IA32_PACKAGE_THERM_INTERRUPT, &l, &h);
+
+	if (rp->power_limit_irq & PACKAGE_THERM_INT_PLN_ENABLE)
+		l |= PACKAGE_THERM_INT_PLN_ENABLE;
+	else
+		l &= ~PACKAGE_THERM_INT_PLN_ENABLE;
+
+	wrmsr_safe(MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
 }
 
 /* restore per package power limit interrupt enable state */
 static void package_power_limit_irq_restore(int package_id)
 {
-	u32 l, h;
 	int cpu;
 	struct rapl_package *rp;
 
@@ -951,14 +982,8 @@ static void package_power_limit_irq_restore(int package_id)
 	/* irq enable state not saved, nothing to restore */
 	if (!(rp->power_limit_irq & PACKAGE_PLN_INT_SAVED))
 		return;
-	rdmsr_safe_on_cpu(cpu, MSR_IA32_PACKAGE_THERM_INTERRUPT, &l, &h);
-
-	if (rp->power_limit_irq & PACKAGE_THERM_INT_PLN_ENABLE)
-		l |= PACKAGE_THERM_INT_PLN_ENABLE;
-	else
-		l &= ~PACKAGE_THERM_INT_PLN_ENABLE;
 
-	wrmsr_on_cpu(cpu, MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
+	smp_call_function_single(cpu, power_limit_irq_restore_cpu, rp, 1);
 }
 
 static void set_floor_freq_default(struct rapl_domain *rd, bool mode)
-- 
1.9.1

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#1286096

On Mon, 2015-12-07 at 15:01 -0800, Jacob Pan wrote:
> Reduce remote CPU calls for MSR access by combining read
> modify write into one function.
> 
> Suggested-by: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
>  drivers/powercap/intel_rapl.c | 91 +++++++++++++++++++++++++++----------------
>  1 file changed, 58 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
> index cc97f08..620c916 100644
> --- a/drivers/powercap/intel_rapl.c
> +++ b/drivers/powercap/intel_rapl.c
> @@ -800,33 +800,43 @@ static int rapl_read_data_raw(struct rapl_domain *rd,
>  	return 0;
>  }
>  
> +struct rapl_msr_action {
> +	u32 msr;
> +	unsigned long long value;
> +	int shift;
> +	u64 mask;
> +};
> +
> +static void rapl_write_data_cpu(void *info)
> +{
> +	u64 msr_val;
> +	struct rapl_msr_action *ra = (struct rapl_msr_action *)info;
> +
> +	rdmsrl_safe(ra->msr, &msr_val);
> +	msr_val &= ~ra->mask;
> +	msr_val |= ra->value << ra->shift;
> +	wrmsrl_safe(ra->msr, msr_val);
What about adding additional common interface
wrmsrl_safe_update(), so that everyone can use this?

> +}
> +
>  /* Similar use of primitive info in the read counterpart */
>  static int rapl_write_data_raw(struct rapl_domain *rd,
>  			enum rapl_primitives prim,
>  			unsigned long long value)
>  {
> -	u64 msr_val;
> -	u32 msr;
> +
> +	struct rapl_msr_action ra;
>  	struct rapl_primitive_info *rp = &rpi[prim];
>  	int cpu;
>  
>  	cpu = find_active_cpu_on_package(rd->package_id);
>  	if (cpu < 0)
>  		return cpu;
> -	msr = rd->msrs[rp->id];
> -	if (rdmsrl_safe_on_cpu(cpu, msr, &msr_val)) {
> -		dev_dbg(&rd->power_zone.dev,
> -			"failed to read msr 0x%x on cpu %d\n", msr, cpu);
> -		return -EIO;
> -	}
> -	value = rapl_unit_xlate(rd, rd->package_id, rp->unit, value, 1);
> -	msr_val &= ~rp->mask;
> -	msr_val |= value << rp->shift;
> -	if (wrmsrl_safe_on_cpu(cpu, msr, msr_val)) {
> -		dev_dbg(&rd->power_zone.dev,
> -			"failed to write msr 0x%x on cpu %d\n", msr, cpu);
> -		return -EIO;
> -	}
> +
> +	ra.msr = rd->msrs[rp->id];
> +	ra.shift = rp->shift;
> +	ra.mask = rp->mask;
> +	ra.value = rapl_unit_xlate(rd, rd->package_id, rp->unit, value, 1);
> +	smp_call_function_single(cpu, rapl_write_data_cpu, &ra, 1);
>  
>  	return 0;
>  }
> @@ -893,6 +903,21 @@ static int rapl_check_unit_atom(struct rapl_package *rp, int cpu)
>  	return 0;
>  }
>  
> +static void power_limit_irq_save_cpu(void *info)
> +{
> +	u32 l, h = 0;
> +	struct rapl_package *rp = (struct rapl_package *)info;
> +
> +	/* save the state of PLN irq mask bit before disabling it */
> +	rdmsr_safe(MSR_IA32_PACKAGE_THERM_INTERRUPT, &l, &h);
> +	if (!(rp->power_limit_irq & PACKAGE_PLN_INT_SAVED)) {
> +		rp->power_limit_irq = l & PACKAGE_THERM_INT_PLN_ENABLE;
> +		rp->power_limit_irq |= PACKAGE_PLN_INT_SAVED;
> +	}
> +	l &= ~PACKAGE_THERM_INT_PLN_ENABLE;
> +	wrmsr_safe(MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
> +}
> +
>  
>  /* REVISIT:
>   * When package power limit is set artificially low by RAPL, LVT
> @@ -906,7 +931,6 @@ static int rapl_check_unit_atom(struct rapl_package *rp, int cpu)
>  
>  static void package_power_limit_irq_save(int package_id)
>  {
> -	u32 l, h = 0;
>  	int cpu;
>  	struct rapl_package *rp;
>  
> @@ -920,20 +944,27 @@ static void package_power_limit_irq_save(int package_id)
>  	cpu = find_active_cpu_on_package(package_id);
>  	if (cpu < 0)
>  		return;
> -	/* save the state of PLN irq mask bit before disabling it */
> -	rdmsr_safe_on_cpu(cpu, MSR_IA32_PACKAGE_THERM_INTERRUPT, &l, &h);
> -	if (!(rp->power_limit_irq & PACKAGE_PLN_INT_SAVED)) {
> -		rp->power_limit_irq = l & PACKAGE_THERM_INT_PLN_ENABLE;
> -		rp->power_limit_irq |= PACKAGE_PLN_INT_SAVED;
> -	}
> -	l &= ~PACKAGE_THERM_INT_PLN_ENABLE;
> -	wrmsr_on_cpu(cpu, MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
> +	smp_call_function_single(cpu, power_limit_irq_save_cpu, rp, 1);
> +}
> +
> +static void power_limit_irq_restore_cpu(void *info)
> +{
> +	u32 l, h = 0;
> +	struct rapl_package *rp = (struct rapl_package *)info;
> +
> +	rdmsr_safe(MSR_IA32_PACKAGE_THERM_INTERRUPT, &l, &h);
> +
> +	if (rp->power_limit_irq & PACKAGE_THERM_INT_PLN_ENABLE)
> +		l |= PACKAGE_THERM_INT_PLN_ENABLE;
> +	else
> +		l &= ~PACKAGE_THERM_INT_PLN_ENABLE;
> +
> +	wrmsr_safe(MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
>  }
>  
>  /* restore per package power limit interrupt enable state */
>  static void package_power_limit_irq_restore(int package_id)
>  {
> -	u32 l, h;
>  	int cpu;
>  	struct rapl_package *rp;
>  
> @@ -951,14 +982,8 @@ static void package_power_limit_irq_restore(int package_id)
>  	/* irq enable state not saved, nothing to restore */
>  	if (!(rp->power_limit_irq & PACKAGE_PLN_INT_SAVED))
>  		return;
> -	rdmsr_safe_on_cpu(cpu, MSR_IA32_PACKAGE_THERM_INTERRUPT, &l, &h);
> -
> -	if (rp->power_limit_irq & PACKAGE_THERM_INT_PLN_ENABLE)
> -		l |= PACKAGE_THERM_INT_PLN_ENABLE;
> -	else
> -		l &= ~PACKAGE_THERM_INT_PLN_ENABLE;
>  
> -	wrmsr_on_cpu(cpu, MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
> +	smp_call_function_single(cpu, power_limit_irq_restore_cpu, rp, 1);
>  }
>  
>  static void set_floor_freq_default(struct rapl_domain *rd, bool mode)


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#1286330

On Mon, Dec 07, 2015 at 03:23:22PM -0800, Srinivas Pandruvada wrote:
> On Mon, 2015-12-07 at 15:01 -0800, Jacob Pan wrote:
> > +struct rapl_msr_action {
> > +	u32 msr;
> > +	unsigned long long value;
> > +	int shift;
> > +	u64 mask;
> > +};
> > +
> > +static void rapl_write_data_cpu(void *info)
> > +{
> > +	u64 msr_val;
> > +	struct rapl_msr_action *ra = (struct rapl_msr_action *)info;
> > +
> > +	rdmsrl_safe(ra->msr, &msr_val);
> > +	msr_val &= ~ra->mask;
> > +	msr_val |= ra->value << ra->shift;
> > +	wrmsrl_safe(ra->msr, msr_val);
> What about adding additional common interface
> wrmsrl_safe_update(), so that everyone can use this?
> 

In which case you want a return value. Also, instead of the value,shift
pair I would add another u64.

Something like:

struct msr_action {
	u32 msr;
	int ret;
	u64 mask, bits;
};

static void msr_update_function(void *info)
{
	struct msr_action *ma = info;
	int ret = 0;
	u64 val;

	ret = rdmsrl_safe(ma->msr, &val);
	if (ret)
		goto out;

	val &= ma->mask;
	val |= ma->bits;

	ret = wrmsrl_safe(ma->msr, val);

out:
	ma->ret = ret;
}

int rmwmsrl_safe_on_cpu(u32 msr, int cpu, u64 mask, u64 bits)
{
	struct msr_action ma = {
		.msr = msr,
		.mask = mask,
		.bits = bits,
	};
	int ret;

	ret = smp_call_function_single(cpu, msr_update_func, &ma, 1);
	if (!ret)
		ret = ma.ret;

	return ret;
}

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