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powerpc/sysfs: Show idle_purr and idle_spurr for every CPU 

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 "purr" and "spurr". This patch adds support for exposing
the idle PURR and SPURR ticks via new per-cpu sysfs files named
"idle_purr" and "idle_spurr".

This patch also adds helper functions to accurately read the values of
idle_purr and idle_spurr especially from an interrupt context between
when the interrupt has occurred between the pseries_idle_prolog() and
pseries_idle_epilog(). This will ensure that the idle purr/spurr
values corresponding to the latest idle period is accounted for before
these values are read.

Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1586249263-14048-5-git-send-email-ego@linux.vnet.ibm.com
This commit is contained in:
Gautham R. Shenoy 2020-04-07 14:17:42 +05:30 committed by Michael Ellerman
parent dc8afce5f4
commit 6909f179ca
2 changed files with 111 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
arch/powerpc/include/asm/idle.h
View File

@ -57,5 +57,37 @@ static inline void pseries_idle_epilog(void)
ppc64_runlatch_on();
}
static inline u64 read_this_idle_purr(void)
{
/*
* If we are reading from an idle context, update the
* idle-purr cycles corresponding to the last idle period.
* Since the idle context is not yet over, take a fresh
* snapshot of the idle-purr.
*/
if (unlikely(get_lppaca()->idle == 1)) {
update_idle_purr_accounting();
snapshot_purr_idle_entry();
}
return be64_to_cpu(get_lppaca()->wait_state_cycles);
}
static inline u64 read_this_idle_spurr(void)
{
/*
* If we are reading from an idle context, update the
* idle-spurr cycles corresponding to the last idle period.
* Since the idle context is not yet over, take a fresh
* snapshot of the idle-spurr.
*/
if (get_lppaca()->idle == 1) {
update_idle_spurr_accounting();
snapshot_spurr_idle_entry();
}
return *this_cpu_ptr(&idle_spurr_cycles);
}
#endif /* CONFIG_PPC_PSERIES */
#endif

82
arch/powerpc/kernel/sysfs.c
View File

@ -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"
@ -760,6 +761,74 @@ static void create_svm_file(void)
}
#endif /* CONFIG_PPC_SVM */
#ifdef CONFIG_PPC_PSERIES
static void read_idle_purr(void *val)
{
u64 *ret = val;
*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 create_idle_purr_file(struct device *s)
{
if (firmware_has_feature(FW_FEATURE_LPAR))
device_create_file(s, &dev_attr_idle_purr);
}
static void remove_idle_purr_file(struct device *s)
{
if (firmware_has_feature(FW_FEATURE_LPAR))
device_remove_file(s, &dev_attr_idle_purr);
}
static void read_idle_spurr(void *val)
{
u64 *ret = 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);
static void create_idle_spurr_file(struct device *s)
{
if (firmware_has_feature(FW_FEATURE_LPAR))
device_create_file(s, &dev_attr_idle_spurr);
}
static void remove_idle_spurr_file(struct device *s)
{
if (firmware_has_feature(FW_FEATURE_LPAR))
device_remove_file(s, &dev_attr_idle_spurr);
}
#else /* CONFIG_PPC_PSERIES */
#define create_idle_purr_file(s)
#define remove_idle_purr_file(s)
#define create_idle_spurr_file(s)
#define remove_idle_spurr_file(s)
#endif /* CONFIG_PPC_PSERIES */
static int register_cpu_online(unsigned int cpu)
{
struct cpu *c = &per_cpu(cpu_devices, cpu);
@ -823,10 +892,13 @@ 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);
create_idle_purr_file(s);
}
if (cpu_has_feature(CPU_FTR_SPURR))
if (cpu_has_feature(CPU_FTR_SPURR)) {
device_create_file(s, &dev_attr_spurr);
create_idle_spurr_file(s);
}
if (cpu_has_feature(CPU_FTR_DSCR))
device_create_file(s, &dev_attr_dscr);
@ -910,11 +982,15 @@ static int unregister_cpu_online(unsigned int cpu)
device_remove_file(s, &dev_attr_mmcra);
#endif /* CONFIG_PMU_SYSFS */
if (cpu_has_feature(CPU_FTR_PURR))
if (cpu_has_feature(CPU_FTR_PURR)) {
device_remove_file(s, &dev_attr_purr);
remove_idle_purr_file(s);
}
if (cpu_has_feature(CPU_FTR_SPURR))
if (cpu_has_feature(CPU_FTR_SPURR)) {
device_remove_file(s, &dev_attr_spurr);
remove_idle_spurr_file(s);
}
if (cpu_has_feature(CPU_FTR_DSCR))
device_remove_file(s, &dev_attr_dscr);