On 11/27/19 5:31 PM, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" <e...@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.
The patch looks good to me, with a minor file mode nit pick mentioned below.
>
> Signed-off-by: Gautham R. Shenoy <e...@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);
per cpu purr/spurr sysfs file is created with file mode 0400. Using
DEVICE_ATTR_RO for their idle_* variants will create sysfs files with 0444 as
their file mode, you should probably use DEVICE_ATTR() with file mode 0400 to
have consist permission for both variants.
--
Kamalesh
