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Date: Mon, 07 Dec 2015 15:23:22 -0800
From: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Linux PM <linux-pm@...r.kernel.org>,
Rafael Wysocki <rafael.j.wysocki@...el.com>,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] powercap/rapl: reduce ipi calls
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@...radead.org>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.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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