"Gautham R. Shenoy" <e...@linux.vnet.ibm.com> writes:
> diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
> index 80a676d..5b4b450 100644
> --- a/arch/powerpc/kernel/sysfs.c
> +++ b/arch/powerpc/kernel/sysfs.c
> @@ -19,6 +19,7 @@
> #include <asm/smp.h>
> #include <asm/pmc.h>
> #include <asm/firmware.h>
> +#include <asm/idle.h>
> #include <asm/svm.h>
>
> #include "cacheinfo.h"
> @@ -733,6 +734,42 @@ static void create_svm_file(void)
> }
> #endif /* CONFIG_PPC_SVM */
>
> +static void read_idle_purr(void *val)
> +{
> + u64 *ret = (u64 *)val;
No cast from void* needed.
> +
> + *ret = read_this_idle_purr();
> +}
> +
> +static ssize_t idle_purr_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct cpu *cpu = container_of(dev, struct cpu, dev);
> + u64 val;
> +
> + smp_call_function_single(cpu->dev.id, read_idle_purr, &val, 1);
> + return sprintf(buf, "%llx\n", val);
> +}
> +static DEVICE_ATTR(idle_purr, 0400, idle_purr_show, NULL);
> +
> +static void read_idle_spurr(void *val)
> +{
> + u64 *ret = (u64 *)val;
> +
> + *ret = read_this_idle_spurr();
> +}
> +
> +static ssize_t idle_spurr_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct cpu *cpu = container_of(dev, struct cpu, dev);
> + u64 val;
> +
> + smp_call_function_single(cpu->dev.id, read_idle_spurr, &val, 1);
> + return sprintf(buf, "%llx\n", val);
> +}
> +static DEVICE_ATTR(idle_spurr, 0400, idle_spurr_show, NULL);
It's regrettable that we have to wake up potentially idle CPUs in order
to derive correct idle statistics for them, but I suppose the main user
(lparstat) of these interfaces already is causing this to happen by
polling the existing per-cpu purr and spurr attributes.
So now lparstat will incur at minimum four syscalls and four IPIs per
CPU per polling interval -- one for each of purr, spurr, idle_purr and
idle_spurr. Correct?
At some point it's going to make sense to batch sampling of remote CPUs'
SPRs.
> static int register_cpu_online(unsigned int cpu)
> {
> struct cpu *c = &per_cpu(cpu_devices, cpu);
> @@ -794,10 +831,15 @@ static int register_cpu_online(unsigned int cpu)
> if (!firmware_has_feature(FW_FEATURE_LPAR))
> add_write_permission_dev_attr(&dev_attr_purr);
> device_create_file(s, &dev_attr_purr);
> + if (firmware_has_feature(FW_FEATURE_LPAR))
> + device_create_file(s, &dev_attr_idle_purr);
> }
>
> - if (cpu_has_feature(CPU_FTR_SPURR))
> + if (cpu_has_feature(CPU_FTR_SPURR)) {
> device_create_file(s, &dev_attr_spurr);
> + if (firmware_has_feature(FW_FEATURE_LPAR))
> + device_create_file(s, &dev_attr_idle_spurr);
> + }
>
> if (cpu_has_feature(CPU_FTR_DSCR))
> device_create_file(s, &dev_attr_dscr);
> @@ -879,11 +921,17 @@ static int unregister_cpu_online(unsigned int cpu)
> if (cpu_has_feature(CPU_FTR_MMCRA))
> device_remove_file(s, &dev_attr_mmcra);
>
> - if (cpu_has_feature(CPU_FTR_PURR))
> + if (cpu_has_feature(CPU_FTR_PURR)) {
> device_remove_file(s, &dev_attr_purr);
> + if (firmware_has_feature(FW_FEATURE_LPAR))
> + device_remove_file(s, &dev_attr_idle_purr);
> + }
>
> - if (cpu_has_feature(CPU_FTR_SPURR))
> + if (cpu_has_feature(CPU_FTR_SPURR)) {
> device_remove_file(s, &dev_attr_spurr);
> + if (firmware_has_feature(FW_FEATURE_LPAR))
> + device_remove_file(s, &dev_attr_idle_spurr);
> + }
>
> if (cpu_has_feature(CPU_FTR_DSCR))
> device_remove_file(s, &dev_attr_dscr);
The cpu register/unregister stuff here looks correct.
