Commit 6909f179 authored by Gautham R. Shenoy's avatar Gautham R. Shenoy Committed by Michael Ellerman
Browse files

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: default avatarGautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1586249263-14048-5-git-send-email-ego@linux.vnet.ibm.com
parent dc8afce5

arch/powerpc/include/asm/idle.h

+32 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/kernel/sysfs.c

+79 −3
Original line number Diff line number Diff line
@@ -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);

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