On Friday, January 15, 2016 11:04:13 AM Jacob Pan wrote:
> Reduce remote CPU calls for MSR access by combining read
> modify write into one function. Also optimize search for active CPU on
> package such that remote CPU is not used if the current CPU is already
> on the target package.
>
> Suggested-by: Peter Zijlstra <pet...@infradead.org>
> Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com>
I'm wondering if there are any comments on this one?
> ---
> drivers/powercap/intel_rapl.c | 122
> ++++++++++++++++++++++++++++++------------
> 1 file changed, 87 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
> index 48747c2..2dcd95f 100644
> --- a/drivers/powercap/intel_rapl.c
> +++ b/drivers/powercap/intel_rapl.c
> @@ -133,6 +133,12 @@ struct rapl_domain_data {
> unsigned long timestamp;
> };
>
> +struct msrl_action {
> + u32 msr_no;
> + u64 clear_mask;
> + u64 set_mask;
> + int err;
> +};
>
> #define DOMAIN_STATE_INACTIVE BIT(0)
> #define DOMAIN_STATE_POWER_LIMIT_SET BIT(1)
> @@ -263,7 +269,11 @@ static struct rapl_package *find_package_by_id(int id)
> /* caller to ensure CPU hotplug lock is held */
> static int find_active_cpu_on_package(int package_id)
> {
> - int i;
> + /* try to avoid remote cpu call, use raw since we are preemptible */
> + int i = raw_smp_processor_id();
> +
> + if (topology_physical_package_id(i) == package_id)
> + return i;
>
> for_each_online_cpu(i) {
> if (topology_physical_package_id(i) == package_id)
> @@ -800,35 +810,62 @@ static int rapl_read_data_raw(struct rapl_domain *rd,
> return 0;
> }
>
> +
> +static int msrl_update_safe(u32 msr_no, u64 clear_mask, u64 set_mask)
> +{
> + int err;
> + u64 val;
> +
> + err = rdmsrl_safe(msr_no, &val);
> + if (err)
> + goto out;
> +
> + val &= ~clear_mask;
> + val |= set_mask;
> +
> + err = wrmsrl_safe(msr_no, val);
> +
> +out:
> + return err;
> +}
> +
> +static void msrl_update_func(void *info)
> +{
> + struct msrl_action *ma = info;
> +
> + ma->err = msrl_update_safe(ma->msr_no, ma->clear_mask, ma->set_mask);
> +}
> +
> /* 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_primitive_info *rp = &rpi[prim];
> int cpu;
> + u64 bits;
> + struct msrl_action ma;
> + int ret;
>
> 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;
> - }
>
> - return 0;
> + bits = rapl_unit_xlate(rd, rd->package_id, rp->unit, value, 1);
> + bits |= bits << rp->shift;
> + memset(&ma, 0, sizeof(ma));
> +
> + ma.msr_no = rd->msrs[rp->id];
> + ma.clear_mask = rp->mask;
> + ma.set_mask = bits;
> +
> + ret = smp_call_function_single(cpu, msrl_update_func, &ma, 1);
> + if (ret)
> + WARN_ON_ONCE(ret);
> + else
> + ret = ma.err;
> +
> + return ret;
> }
>
> /*
> @@ -893,6 +930,21 @@ 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 +958,6 @@ 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 +971,27 @@ 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 +1009,8 @@ 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)
>
