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-rw-r--r--drivers/oprofile/buffer_sync.c65
-rw-r--r--drivers/oprofile/cpu_buffer.c63
-rw-r--r--drivers/oprofile/cpu_buffer.h71
3 files changed, 114 insertions, 85 deletions
diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c
index 944a5832d9e4..737bd9484822 100644
--- a/drivers/oprofile/buffer_sync.c
+++ b/drivers/oprofile/buffer_sync.c
@@ -268,18 +268,6 @@ lookup_dcookie(struct mm_struct *mm, unsigned long addr, off_t *offset)
return cookie;
}
-static void increment_tail(struct oprofile_cpu_buffer *b)
-{
- unsigned long new_tail = b->tail_pos + 1;
-
- rmb(); /* be sure fifo pointers are synchronized */
-
- if (new_tail < b->buffer_size)
- b->tail_pos = new_tail;
- else
- b->tail_pos = 0;
-}
-
static unsigned long last_cookie = INVALID_COOKIE;
static void add_cpu_switch(int i)
@@ -331,26 +319,25 @@ static void add_trace_begin(void)
#define IBS_FETCH_CODE_SIZE 2
#define IBS_OP_CODE_SIZE 5
-#define IBS_EIP(cpu_buf) ((cpu_buffer_read_entry(cpu_buf))->eip)
-#define IBS_EVENT(cpu_buf) ((cpu_buffer_read_entry(cpu_buf))->event)
/*
* Add IBS fetch and op entries to event buffer
*/
-static void add_ibs_begin(struct oprofile_cpu_buffer *cpu_buf, int code,
- struct mm_struct *mm)
+static void add_ibs_begin(int cpu, int code, struct mm_struct *mm)
{
unsigned long rip;
int i, count;
unsigned long ibs_cookie = 0;
off_t offset;
+ struct op_sample *sample;
- increment_tail(cpu_buf); /* move to RIP entry */
-
- rip = IBS_EIP(cpu_buf);
+ sample = cpu_buffer_read_entry(cpu);
+ if (!sample)
+ goto Error;
+ rip = sample->eip;
#ifdef __LP64__
- rip += IBS_EVENT(cpu_buf) << 32;
+ rip += sample->event << 32;
#endif
if (mm) {
@@ -374,8 +361,8 @@ static void add_ibs_begin(struct oprofile_cpu_buffer *cpu_buf, int code,
add_event_entry(offset); /* Offset from Dcookie */
/* we send the Dcookie offset, but send the raw Linear Add also*/
- add_event_entry(IBS_EIP(cpu_buf));
- add_event_entry(IBS_EVENT(cpu_buf));
+ add_event_entry(sample->eip);
+ add_event_entry(sample->event);
if (code == IBS_FETCH_CODE)
count = IBS_FETCH_CODE_SIZE; /*IBS FETCH is 2 int64s*/
@@ -383,10 +370,17 @@ static void add_ibs_begin(struct oprofile_cpu_buffer *cpu_buf, int code,
count = IBS_OP_CODE_SIZE; /*IBS OP is 5 int64s*/
for (i = 0; i < count; i++) {
- increment_tail(cpu_buf);
- add_event_entry(IBS_EIP(cpu_buf));
- add_event_entry(IBS_EVENT(cpu_buf));
+ sample = cpu_buffer_read_entry(cpu);
+ if (!sample)
+ goto Error;
+ add_event_entry(sample->eip);
+ add_event_entry(sample->event);
}
+
+ return;
+
+Error:
+ return;
}
#endif
@@ -530,33 +524,26 @@ typedef enum {
*/
void sync_buffer(int cpu)
{
- struct oprofile_cpu_buffer *cpu_buf = &per_cpu(cpu_buffer, cpu);
struct mm_struct *mm = NULL;
struct mm_struct *oldmm;
struct task_struct *new;
unsigned long cookie = 0;
int in_kernel = 1;
sync_buffer_state state = sb_buffer_start;
-#ifndef CONFIG_OPROFILE_IBS
unsigned int i;
unsigned long available;
-#endif
mutex_lock(&buffer_mutex);
add_cpu_switch(cpu);
- /* Remember, only we can modify tail_pos */
-
cpu_buffer_reset(cpu);
-#ifndef CONFIG_OPROFILE_IBS
- available = cpu_buffer_entries(cpu_buf);
+ available = cpu_buffer_entries(cpu);
for (i = 0; i < available; ++i) {
-#else
- while (cpu_buffer_entries(cpu_buf)) {
-#endif
- struct op_sample *s = cpu_buffer_read_entry(cpu_buf);
+ struct op_sample *s = cpu_buffer_read_entry(cpu);
+ if (!s)
+ break;
if (is_code(s->eip)) {
switch (s->event) {
@@ -575,11 +562,11 @@ void sync_buffer(int cpu)
#ifdef CONFIG_OPROFILE_IBS
case IBS_FETCH_BEGIN:
state = sb_bt_start;
- add_ibs_begin(cpu_buf, IBS_FETCH_CODE, mm);
+ add_ibs_begin(cpu, IBS_FETCH_CODE, mm);
break;
case IBS_OP_BEGIN:
state = sb_bt_start;
- add_ibs_begin(cpu_buf, IBS_OP_CODE, mm);
+ add_ibs_begin(cpu, IBS_OP_CODE, mm);
break;
#endif
default:
@@ -600,8 +587,6 @@ void sync_buffer(int cpu)
atomic_inc(&oprofile_stats.bt_lost_no_mapping);
}
}
-
- increment_tail(cpu_buf);
}
release_mm(mm);
diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
index 5cf7efe38e67..eb280ec96e24 100644
--- a/drivers/oprofile/cpu_buffer.c
+++ b/drivers/oprofile/cpu_buffer.c
@@ -28,6 +28,25 @@
#include "buffer_sync.h"
#include "oprof.h"
+#define OP_BUFFER_FLAGS 0
+
+/*
+ * Read and write access is using spin locking. Thus, writing to the
+ * buffer by NMI handler (x86) could occur also during critical
+ * sections when reading the buffer. To avoid this, there are 2
+ * buffers for independent read and write access. Read access is in
+ * process context only, write access only in the NMI handler. If the
+ * read buffer runs empty, both buffers are swapped atomically. There
+ * is potentially a small window during swapping where the buffers are
+ * disabled and samples could be lost.
+ *
+ * Using 2 buffers is a little bit overhead, but the solution is clear
+ * and does not require changes in the ring buffer implementation. It
+ * can be changed to a single buffer solution when the ring buffer
+ * access is implemented as non-locking atomic code.
+ */
+struct ring_buffer *op_ring_buffer_read;
+struct ring_buffer *op_ring_buffer_write;
DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
static void wq_sync_buffer(struct work_struct *work);
@@ -37,12 +56,12 @@ static int work_enabled;
void free_cpu_buffers(void)
{
- int i;
-
- for_each_possible_cpu(i) {
- vfree(per_cpu(cpu_buffer, i).buffer);
- per_cpu(cpu_buffer, i).buffer = NULL;
- }
+ if (op_ring_buffer_read)
+ ring_buffer_free(op_ring_buffer_read);
+ op_ring_buffer_read = NULL;
+ if (op_ring_buffer_write)
+ ring_buffer_free(op_ring_buffer_write);
+ op_ring_buffer_write = NULL;
}
unsigned long oprofile_get_cpu_buffer_size(void)
@@ -64,14 +83,16 @@ int alloc_cpu_buffers(void)
unsigned long buffer_size = fs_cpu_buffer_size;
+ op_ring_buffer_read = ring_buffer_alloc(buffer_size, OP_BUFFER_FLAGS);
+ if (!op_ring_buffer_read)
+ goto fail;
+ op_ring_buffer_write = ring_buffer_alloc(buffer_size, OP_BUFFER_FLAGS);
+ if (!op_ring_buffer_write)
+ goto fail;
+
for_each_possible_cpu(i) {
struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
- b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size,
- cpu_to_node(i));
- if (!b->buffer)
- goto fail;
-
b->last_task = NULL;
b->last_is_kernel = -1;
b->tracing = 0;
@@ -140,10 +161,22 @@ static inline void
add_sample(struct oprofile_cpu_buffer *cpu_buf,
unsigned long pc, unsigned long event)
{
- struct op_sample *entry = cpu_buffer_write_entry(cpu_buf);
- entry->eip = pc;
- entry->event = event;
- cpu_buffer_write_commit(cpu_buf);
+ struct op_entry entry;
+
+ if (cpu_buffer_write_entry(&entry))
+ goto Error;
+
+ entry.sample->eip = pc;
+ entry.sample->event = event;
+
+ if (cpu_buffer_write_commit(&entry))
+ goto Error;
+
+ return;
+
+Error:
+ cpu_buf->sample_lost_overflow++;
+ return;
}
static inline void
diff --git a/drivers/oprofile/cpu_buffer.h b/drivers/oprofile/cpu_buffer.h
index 895763f065e9..aacb0f0bc566 100644
--- a/drivers/oprofile/cpu_buffer.h
+++ b/drivers/oprofile/cpu_buffer.h
@@ -15,6 +15,7 @@
#include <linux/workqueue.h>
#include <linux/cache.h>
#include <linux/sched.h>
+#include <linux/ring_buffer.h>
struct task_struct;
@@ -32,6 +33,12 @@ struct op_sample {
unsigned long event;
};
+struct op_entry {
+ struct ring_buffer_event *event;
+ struct op_sample *sample;
+ unsigned long irq_flags;
+};
+
struct oprofile_cpu_buffer {
volatile unsigned long head_pos;
volatile unsigned long tail_pos;
@@ -39,7 +46,6 @@ struct oprofile_cpu_buffer {
struct task_struct *last_task;
int last_is_kernel;
int tracing;
- struct op_sample *buffer;
unsigned long sample_received;
unsigned long sample_lost_overflow;
unsigned long backtrace_aborted;
@@ -48,6 +54,8 @@ struct oprofile_cpu_buffer {
struct delayed_work work;
};
+extern struct ring_buffer *op_ring_buffer_read;
+extern struct ring_buffer *op_ring_buffer_write;
DECLARE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
/*
@@ -64,46 +72,49 @@ static inline void cpu_buffer_reset(int cpu)
cpu_buf->last_task = NULL;
}
-static inline
-struct op_sample *cpu_buffer_write_entry(struct oprofile_cpu_buffer *cpu_buf)
+static inline int cpu_buffer_write_entry(struct op_entry *entry)
{
- return &cpu_buf->buffer[cpu_buf->head_pos];
-}
+ entry->event = ring_buffer_lock_reserve(op_ring_buffer_write,
+ sizeof(struct op_sample),
+ &entry->irq_flags);
+ if (entry->event)
+ entry->sample = ring_buffer_event_data(entry->event);
+ else
+ entry->sample = NULL;
-static inline
-void cpu_buffer_write_commit(struct oprofile_cpu_buffer *b)
-{
- unsigned long new_head = b->head_pos + 1;
+ if (!entry->sample)
+ return -ENOMEM;
- /*
- * Ensure anything written to the slot before we increment is
- * visible
- */
- wmb();
+ return 0;
+}
- if (new_head < b->buffer_size)
- b->head_pos = new_head;
- else
- b->head_pos = 0;
+static inline int cpu_buffer_write_commit(struct op_entry *entry)
+{
+ return ring_buffer_unlock_commit(op_ring_buffer_write, entry->event,
+ entry->irq_flags);
}
-static inline
-struct op_sample *cpu_buffer_read_entry(struct oprofile_cpu_buffer *cpu_buf)
+static inline struct op_sample *cpu_buffer_read_entry(int cpu)
{
- return &cpu_buf->buffer[cpu_buf->tail_pos];
+ struct ring_buffer_event *e;
+ e = ring_buffer_consume(op_ring_buffer_read, cpu, NULL);
+ if (e)
+ return ring_buffer_event_data(e);
+ if (ring_buffer_swap_cpu(op_ring_buffer_read,
+ op_ring_buffer_write,
+ cpu))
+ return NULL;
+ e = ring_buffer_consume(op_ring_buffer_read, cpu, NULL);
+ if (e)
+ return ring_buffer_event_data(e);
+ return NULL;
}
/* "acquire" as many cpu buffer slots as we can */
-static inline
-unsigned long cpu_buffer_entries(struct oprofile_cpu_buffer *b)
+static inline unsigned long cpu_buffer_entries(int cpu)
{
- unsigned long head = b->head_pos;
- unsigned long tail = b->tail_pos;
-
- if (head >= tail)
- return head - tail;
-
- return head + (b->buffer_size - tail);
+ return ring_buffer_entries_cpu(op_ring_buffer_read, cpu)
+ + ring_buffer_entries_cpu(op_ring_buffer_write, cpu);
}
/* transient events for the CPU buffer -> event buffer */
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