[PATCH v1 1/4] KVM: stats: Support linear and logarithmic histogram statistics

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Add new types of KVM stats, linear and logarithmic histogram.
Histogram are very useful for observing the value distribution
of time or size related stats.

Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
---
 arch/arm64/kvm/guest.c    |  4 ---
 arch/mips/kvm/mips.c      |  4 ---
 arch/powerpc/kvm/book3s.c |  4 ---
 arch/powerpc/kvm/booke.c  |  4 ---
 arch/s390/kvm/kvm-s390.c  |  4 ---
 arch/x86/kvm/x86.c        |  4 ---
 include/linux/kvm_host.h  | 53 ++++++++++++++++++++++++++++-----------
 include/linux/kvm_types.h | 16 ++++++++++++
 include/uapi/linux/kvm.h  | 11 +++++---
 virt/kvm/binary_stats.c   | 36 ++++++++++++++++++++++++++
 10 files changed, 98 insertions(+), 42 deletions(-)

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 1512a8007a78..cb44d8756fa7 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -31,8 +31,6 @@
 const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	KVM_GENERIC_VM_STATS()
 };
-static_assert(ARRAY_SIZE(kvm_vm_stats_desc) ==
-		sizeof(struct kvm_vm_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vm_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
@@ -52,8 +50,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
 	STATS_DESC_COUNTER(VCPU, mmio_exit_kernel),
 	STATS_DESC_COUNTER(VCPU, exits)
 };
-static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) ==
-		sizeof(struct kvm_vcpu_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vcpu_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index af9dd029a4e1..75c6f264c626 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -41,8 +41,6 @@
 const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	KVM_GENERIC_VM_STATS()
 };
-static_assert(ARRAY_SIZE(kvm_vm_stats_desc) ==
-		sizeof(struct kvm_vm_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vm_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
@@ -85,8 +83,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
 	STATS_DESC_COUNTER(VCPU, vz_cpucfg_exits),
 #endif
 };
-static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) ==
-		sizeof(struct kvm_vcpu_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vcpu_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 79833f78d1da..5cc6e90095b0 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -43,8 +43,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	STATS_DESC_ICOUNTER(VM, num_2M_pages),
 	STATS_DESC_ICOUNTER(VM, num_1G_pages)
 };
-static_assert(ARRAY_SIZE(kvm_vm_stats_desc) ==
-		sizeof(struct kvm_vm_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vm_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
@@ -88,8 +86,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
 	STATS_DESC_COUNTER(VCPU, pthru_host),
 	STATS_DESC_COUNTER(VCPU, pthru_bad_aff)
 };
-static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) ==
-		sizeof(struct kvm_vcpu_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vcpu_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 551b30d84aee..5ed6c235e059 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -41,8 +41,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	STATS_DESC_ICOUNTER(VM, num_2M_pages),
 	STATS_DESC_ICOUNTER(VM, num_1G_pages)
 };
-static_assert(ARRAY_SIZE(kvm_vm_stats_desc) ==
-		sizeof(struct kvm_vm_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vm_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
@@ -79,8 +77,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
 	STATS_DESC_COUNTER(VCPU, pthru_host),
 	STATS_DESC_COUNTER(VCPU, pthru_bad_aff)
 };
-static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) ==
-		sizeof(struct kvm_vcpu_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vcpu_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 1695f0ced5ba..7610d33d319b 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -66,8 +66,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	STATS_DESC_COUNTER(VM, inject_service_signal),
 	STATS_DESC_COUNTER(VM, inject_virtio)
 };
-static_assert(ARRAY_SIZE(kvm_vm_stats_desc) ==
-		sizeof(struct kvm_vm_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vm_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
@@ -174,8 +172,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
 	STATS_DESC_COUNTER(VCPU, diagnose_other),
 	STATS_DESC_COUNTER(VCPU, pfault_sync)
 };
-static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) ==
-		sizeof(struct kvm_vcpu_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vcpu_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8166ad113fb2..b94a80ad5b8d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -239,8 +239,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	STATS_DESC_ICOUNTER(VM, nx_lpage_splits),
 	STATS_DESC_PCOUNTER(VM, max_mmu_page_hash_collisions)
 };
-static_assert(ARRAY_SIZE(kvm_vm_stats_desc) ==
-		sizeof(struct kvm_vm_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vm_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
@@ -280,8 +278,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
 	STATS_DESC_COUNTER(VCPU, directed_yield_successful),
 	STATS_DESC_ICOUNTER(VCPU, guest_mode)
 };
-static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) ==
-		sizeof(struct kvm_vcpu_stat) / sizeof(u64));
 
 const struct kvm_stats_header kvm_vcpu_stats_header = {
 	.name_size = KVM_STATS_NAME_SIZE,
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ae7735b490b4..356af173114d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1273,56 +1273,66 @@ struct _kvm_stats_desc {
 	char name[KVM_STATS_NAME_SIZE];
 };
 
-#define STATS_DESC_COMMON(type, unit, base, exp)			       \
+#define STATS_DESC_COMMON(type, unit, base, exp, sz, param)		       \
 	.flags = type | unit | base |					       \
 		 BUILD_BUG_ON_ZERO(type & ~KVM_STATS_TYPE_MASK) |	       \
 		 BUILD_BUG_ON_ZERO(unit & ~KVM_STATS_UNIT_MASK) |	       \
 		 BUILD_BUG_ON_ZERO(base & ~KVM_STATS_BASE_MASK),	       \
 	.exponent = exp,						       \
-	.size = 1
+	.size = sz,							       \
+	.hist_param = param
 
-#define VM_GENERIC_STATS_DESC(stat, type, unit, base, exp)		       \
+#define VM_GENERIC_STATS_DESC(stat, type, unit, base, exp, sz, param)	       \
 	{								       \
 		{							       \
-			STATS_DESC_COMMON(type, unit, base, exp),	       \
+			STATS_DESC_COMMON(type, unit, base, exp, sz, param),   \
 			.offset = offsetof(struct kvm_vm_stat, generic.stat)   \
 		},							       \
 		.name = #stat,						       \
 	}
-#define VCPU_GENERIC_STATS_DESC(stat, type, unit, base, exp)		       \
+#define VCPU_GENERIC_STATS_DESC(stat, type, unit, base, exp, sz, param)	       \
 	{								       \
 		{							       \
-			STATS_DESC_COMMON(type, unit, base, exp),	       \
+			STATS_DESC_COMMON(type, unit, base, exp, sz, param),   \
 			.offset = offsetof(struct kvm_vcpu_stat, generic.stat) \
 		},							       \
 		.name = #stat,						       \
 	}
-#define VM_STATS_DESC(stat, type, unit, base, exp)			       \
+#define VM_STATS_DESC(stat, type, unit, base, exp, sz, param)		       \
 	{								       \
 		{							       \
-			STATS_DESC_COMMON(type, unit, base, exp),	       \
+			STATS_DESC_COMMON(type, unit, base, exp, sz, param),   \
 			.offset = offsetof(struct kvm_vm_stat, stat)	       \
 		},							       \
 		.name = #stat,						       \
 	}
-#define VCPU_STATS_DESC(stat, type, unit, base, exp)			       \
+#define VCPU_STATS_DESC(stat, type, unit, base, exp, sz, param)		       \
 	{								       \
 		{							       \
-			STATS_DESC_COMMON(type, unit, base, exp),	       \
+			STATS_DESC_COMMON(type, unit, base, exp, sz, param),   \
 			.offset = offsetof(struct kvm_vcpu_stat, stat)	       \
 		},							       \
 		.name = #stat,						       \
 	}
 /* SCOPE: VM, VM_GENERIC, VCPU, VCPU_GENERIC */
-#define STATS_DESC(SCOPE, stat, type, unit, base, exp)			       \
-	SCOPE##_STATS_DESC(stat, type, unit, base, exp)
+#define STATS_DESC(SCOPE, stat, type, unit, base, exp, sz, param)	       \
+	SCOPE##_STATS_DESC(stat, type, unit, base, exp, sz, param)
 
 #define STATS_DESC_CUMULATIVE(SCOPE, name, unit, base, exponent)	       \
-	STATS_DESC(SCOPE, name, KVM_STATS_TYPE_CUMULATIVE, unit, base, exponent)
+	STATS_DESC(SCOPE, name, KVM_STATS_TYPE_CUMULATIVE,		       \
+		unit, base, exponent, 1, 0)
 #define STATS_DESC_INSTANT(SCOPE, name, unit, base, exponent)		       \
-	STATS_DESC(SCOPE, name, KVM_STATS_TYPE_INSTANT, unit, base, exponent)
+	STATS_DESC(SCOPE, name, KVM_STATS_TYPE_INSTANT,			       \
+		unit, base, exponent, 1, 0)
 #define STATS_DESC_PEAK(SCOPE, name, unit, base, exponent)		       \
-	STATS_DESC(SCOPE, name, KVM_STATS_TYPE_PEAK, unit, base, exponent)
+	STATS_DESC(SCOPE, name, KVM_STATS_TYPE_PEAK,			       \
+		unit, base, exponent, 1, 0)
+#define STATS_DESC_LINEAR_HIST(SCOPE, name, unit, base, exponent, sz, param)   \
+	STATS_DESC(SCOPE, name, KVM_STATS_TYPE_LINEAR_HIST,		       \
+		unit, base, exponent, sz, param)
+#define STATS_DESC_LOG_HIST(SCOPE, name, unit, base, exponent, sz, param)      \
+	STATS_DESC(SCOPE, name, KVM_STATS_TYPE_LOG_HIST,		       \
+		unit, base, exponent, sz, param)
 
 /* Cumulative counter, read/write */
 #define STATS_DESC_COUNTER(SCOPE, name)					       \
@@ -1341,6 +1351,14 @@ struct _kvm_stats_desc {
 #define STATS_DESC_TIME_NSEC(SCOPE, name)				       \
 	STATS_DESC_CUMULATIVE(SCOPE, name, KVM_STATS_UNIT_SECONDS,	       \
 		KVM_STATS_BASE_POW10, -9)
+/* Linear histogram for time in nanosecond */
+#define STATS_DESC_LINHIST_TIME_NSEC(SCOPE, name, sz, bucket_size)	       \
+	STATS_DESC_LINEAR_HIST(SCOPE, name, KVM_STATS_UNIT_SECONDS,	       \
+		KVM_STATS_BASE_POW10, -9, sz, bucket_size)
+/* Logarithmic histogram for time in nanosecond */
+#define STATS_DESC_LOGHIST_TIME_NSEC(SCOPE, name, sz)			       \
+	STATS_DESC_LOG_HIST(SCOPE, name, KVM_STATS_UNIT_SECONDS,	       \
+		KVM_STATS_BASE_POW10, -9, sz, LOGHIST_BASE_2)
 
 #define KVM_GENERIC_VM_STATS()						       \
 	STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush)
@@ -1354,10 +1372,15 @@ struct _kvm_stats_desc {
 	STATS_DESC_TIME_NSEC(VCPU_GENERIC, halt_poll_fail_ns)
 
 extern struct dentry *kvm_debugfs_dir;
+
 ssize_t kvm_stats_read(char *id, const struct kvm_stats_header *header,
 		       const struct _kvm_stats_desc *desc,
 		       void *stats, size_t size_stats,
 		       char __user *user_buffer, size_t size, loff_t *offset);
+void kvm_stats_linear_hist_update(u64 *data, size_t size,
+				  u64 value, size_t bucket_size);
+void kvm_stats_log_hist_update(u64 *data, size_t size, u64 value);
+
 extern const struct kvm_stats_header kvm_vm_stats_header;
 extern const struct _kvm_stats_desc kvm_vm_stats_desc[];
 extern const struct kvm_stats_header kvm_vcpu_stats_header;
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index ed6a985c5680..cc88cd676775 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -76,6 +76,22 @@ struct kvm_mmu_memory_cache {
 };
 #endif
 
+/* Constants used for histogram stats */
+#define LINHIST_SIZE_SMALL		10
+#define LINHIST_SIZE_MEDIUM		20
+#define LINHIST_SIZE_LARGE		50
+#define LINHIST_SIZE_XLARGE		100
+#define LINHIST_BUCKET_SIZE_SMALL	10
+#define LINHIST_BUCKET_SIZE_MEDIUM	100
+#define LINHIST_BUCKET_SIZE_LARGE	1000
+#define LINHIST_BUCKET_SIZE_XLARGE	10000
+
+#define LOGHIST_SIZE_SMALL		8
+#define LOGHIST_SIZE_MEDIUM		16
+#define LOGHIST_SIZE_LARGE		32
+#define LOGHIST_SIZE_XLARGE		64
+#define LOGHIST_BASE_2			2
+
 struct kvm_vm_stat_generic {
 	u64 remote_tlb_flush;
 };
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 68c9e6d8bbda..ff34a471d9ef 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1963,7 +1963,9 @@ struct kvm_stats_header {
 #define KVM_STATS_TYPE_CUMULATIVE	(0x0 << KVM_STATS_TYPE_SHIFT)
 #define KVM_STATS_TYPE_INSTANT		(0x1 << KVM_STATS_TYPE_SHIFT)
 #define KVM_STATS_TYPE_PEAK		(0x2 << KVM_STATS_TYPE_SHIFT)
-#define KVM_STATS_TYPE_MAX		KVM_STATS_TYPE_PEAK
+#define KVM_STATS_TYPE_LINEAR_HIST	(0x3 << KVM_STATS_TYPE_SHIFT)
+#define KVM_STATS_TYPE_LOG_HIST		(0x4 << KVM_STATS_TYPE_SHIFT)
+#define KVM_STATS_TYPE_MAX		KVM_STATS_TYPE_LOG_HIST
 
 #define KVM_STATS_UNIT_SHIFT		4
 #define KVM_STATS_UNIT_MASK		(0xF << KVM_STATS_UNIT_SHIFT)
@@ -1987,7 +1989,10 @@ struct kvm_stats_header {
  *        Every data item is of type __u64.
  * @offset: The offset of the stats to the start of stat structure in
  *          struture kvm or kvm_vcpu.
- * @unused: Unused field for future usage. Always 0 for now.
+ * @hist_param: A parameter value used for histogram stats. For linear
+ *              histogram stats, it indicates the size of the bucket;
+ *              For logarithmic histogram stats, it indicates the base
+ *              of the logarithm. Only base of 2 is supported.
  * @name: The name string for the stats. Its size is indicated by the
  *        &kvm_stats_header->name_size.
  */
@@ -1996,7 +2001,7 @@ struct kvm_stats_desc {
 	__s16 exponent;
 	__u16 size;
 	__u32 offset;
-	__u32 unused;
+	__u32 hist_param;
 	char name[];
 };
 
diff --git a/virt/kvm/binary_stats.c b/virt/kvm/binary_stats.c
index e609d428811a..6eead6979a7f 100644
--- a/virt/kvm/binary_stats.c
+++ b/virt/kvm/binary_stats.c
@@ -144,3 +144,39 @@ ssize_t kvm_stats_read(char *id, const struct kvm_stats_header *header,
 	*offset = pos;
 	return len;
 }
+
+/**
+ * kvm_stats_linear_hist_update() - Update bucket value for linear histogram
+ * statistics data.
+ *
+ * @data: start address of the stats data
+ * @size: the number of bucket of the stats data
+ * @value: the new value used to update the linear histogram's bucket
+ * @bucket_size: the size (width) of a bucket
+ */
+void kvm_stats_linear_hist_update(u64 *data, size_t size,
+				  u64 value, size_t bucket_size)
+{
+	size_t index = value / bucket_size;
+
+	if (index >= size)
+		index = size - 1;
+	++data[index];
+}
+
+/**
+ * kvm_stats_log_hist_update() - Update bucket value for logarithmic histogram
+ * statistics data.
+ *
+ * @data: start address of the stats data
+ * @size: the number of bucket of the stats data
+ * @value: the new value used to update the logarithmic histogram's bucket
+ */
+void kvm_stats_log_hist_update(u64 *data, size_t size, u64 value)
+{
+	size_t index = fls64(value);
+
+	if (index >= size)
+		index = size - 1;
+	++data[index];
+}
-- 
2.32.0.93.g670b81a890-goog




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