From 6909f179ca7a73f243dca7c829facca1cc1d4ff5 Mon Sep 17 00:00:00 2001

From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>

Date: Tue, 7 Apr 2020 14:17:42 +0530

Subject: [PATCH] powerpc/sysfs: Show idle_purr and idle_spurr for every CPU

References: PED-3947 bsc#1210544 ltc#202303

Patch-mainline: v5.8-rc1

Git-commit: 6909f179ca7a73f243dca7c829facca1cc1d4ff5

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

Acked-by: Michal Suchanek <msuchanek@suse.de>

---

 arch/powerpc/include/asm/idle.h | 32 +++++++++++++

 arch/powerpc/kernel/sysfs.c     | 82 +++++++++++++++++++++++++++++++--

 2 files changed, 111 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/idle.h b/arch/powerpc/include/asm/idle.h

index 0efb25071d87..accd1f50085a 100644

--- a/arch/powerpc/include/asm/idle.h

+++ b/arch/powerpc/include/asm/idle.h

@@ -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

diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c

--- 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 "cacheinfo.h"

@@ -760,6 +761,74 @@ static void create_svm_file(void)

 #endif /* HAS_PPC_PMC_PA6T */

 #endif /* HAS_PPC_PMC_CLASSIC */

+#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)

 	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);

+		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);

-- 

2.40.0