diff options
| -rw-r--r-- | drivers/oprofile/buffer_sync.c | 65 | ||||
| -rw-r--r-- | drivers/oprofile/cpu_buffer.c | 63 | ||||
| -rw-r--r-- | drivers/oprofile/cpu_buffer.h | 71 |
3 files changed, 114 insertions, 85 deletions
diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c index 944a583..737bd94 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 5cf7efe..eb280ec 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 895763f..aacb0f0 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 */ |
