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SubjectRe: [PATCH 2/3] powerpc/sysfs: Show idle_purr and idle_spurr for every CPU
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Le 27/11/2019 à 13:01, Gautham R. Shenoy a écrit :
> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
>
> On Pseries LPARs, to calculate utilization, we need to know the
> [S]PURR ticks when the CPUs were busy or idle.
>
> The total PURR and SPURR ticks are already exposed via the per-cpu
> sysfs files /sys/devices/system/cpu/cpuX/purr and
> /sys/devices/system/cpu/cpuX/spurr.
>
> This patch adds support for exposing the idle PURR and SPURR ticks via
> /sys/devices/system/cpu/cpuX/idle_purr and
> /sys/devices/system/cpu/cpuX/idle_spurr.

Might be a candid question, but I see in arch/powerpc/kernel/time.c that
PURR/SPURR are already taken into account by the kernel to calculate
utilisation when CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is selected.

As far as I understand, you are wanting to expose this to userland to
redo the calculation there. What is wrong with the values reported by
the kernel ?

Christophe

>
> Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> ---
> arch/powerpc/kernel/sysfs.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
> index 80a676d..42ade55 100644
> --- a/arch/powerpc/kernel/sysfs.c
> +++ b/arch/powerpc/kernel/sysfs.c
> @@ -1044,6 +1044,36 @@ static ssize_t show_physical_id(struct device *dev,
> }
> static DEVICE_ATTR(physical_id, 0444, show_physical_id, NULL);
>
> +static ssize_t idle_purr_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct cpu *cpu = container_of(dev, struct cpu, dev);
> + unsigned int cpuid = cpu->dev.id;
> + struct lppaca *cpu_lppaca_ptr = paca_ptrs[cpuid]->lppaca_ptr;
> + u64 idle_purr_cycles = be64_to_cpu(cpu_lppaca_ptr->wait_state_cycles);
> +
> + return sprintf(buf, "%llx\n", idle_purr_cycles);
> +}
> +static DEVICE_ATTR_RO(idle_purr);
> +
> +DECLARE_PER_CPU(u64, idle_spurr_cycles);
> +static ssize_t idle_spurr_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct cpu *cpu = container_of(dev, struct cpu, dev);
> + unsigned int cpuid = cpu->dev.id;
> + u64 *idle_spurr_cycles_ptr = per_cpu_ptr(&idle_spurr_cycles, cpuid);
> +
> + return sprintf(buf, "%llx\n", *idle_spurr_cycles_ptr);
> +}
> +static DEVICE_ATTR_RO(idle_spurr);
> +
> +static void create_idle_purr_spurr_sysfs_entry(struct device *cpudev)
> +{
> + device_create_file(cpudev, &dev_attr_idle_purr);
> + device_create_file(cpudev, &dev_attr_idle_spurr);
> +}
> +
> static int __init topology_init(void)
> {
> int cpu, r;
> @@ -1067,6 +1097,8 @@ static int __init topology_init(void)
> register_cpu(c, cpu);
>
> device_create_file(&c->dev, &dev_attr_physical_id);
> + if (firmware_has_feature(FW_FEATURE_SPLPAR))
> + create_idle_purr_spurr_sysfs_entry(&c->dev);
> }
> }
> r = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "powerpc/topology:online",
>

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