Commit 37886f6a authored by Steven Rostedt's avatar Steven Rostedt
Browse files

ring-buffer: add api to allow a tracer to change clock source



This patch adds a new function called ring_buffer_set_clock that
allows a tracer to assign its own clock source to the buffer.
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent 6adaad14
......@@ -118,8 +118,11 @@ unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
u64 ring_buffer_time_stamp(int cpu);
void ring_buffer_normalize_time_stamp(int cpu, u64 *ts);
u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
int cpu, u64 *ts);
void ring_buffer_set_clock(struct ring_buffer *buffer,
u64 (*clock)(void));
size_t ring_buffer_page_len(void *page);
......
......@@ -180,29 +180,6 @@ EXPORT_SYMBOL_GPL(tracing_is_on);
#include "trace.h"
/* Up this if you want to test the TIME_EXTENTS and normalization */
#define DEBUG_SHIFT 0
u64 ring_buffer_time_stamp(int cpu)
{
u64 time;
preempt_disable_notrace();
/* shift to debug/test normalization and TIME_EXTENTS */
time = trace_clock_local() << DEBUG_SHIFT;
preempt_enable_no_resched_notrace();
return time;
}
EXPORT_SYMBOL_GPL(ring_buffer_time_stamp);
void ring_buffer_normalize_time_stamp(int cpu, u64 *ts)
{
/* Just stupid testing the normalize function and deltas */
*ts >>= DEBUG_SHIFT;
}
EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp);
#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array))
#define RB_ALIGNMENT 4U
#define RB_MAX_SMALL_DATA 28
......@@ -374,6 +351,7 @@ struct ring_buffer {
#ifdef CONFIG_HOTPLUG_CPU
struct notifier_block cpu_notify;
#endif
u64 (*clock)(void);
};
struct ring_buffer_iter {
......@@ -394,6 +372,30 @@ struct ring_buffer_iter {
_____ret; \
})
/* Up this if you want to test the TIME_EXTENTS and normalization */
#define DEBUG_SHIFT 0
u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu)
{
u64 time;
preempt_disable_notrace();
/* shift to debug/test normalization and TIME_EXTENTS */
time = buffer->clock() << DEBUG_SHIFT;
preempt_enable_no_resched_notrace();
return time;
}
EXPORT_SYMBOL_GPL(ring_buffer_time_stamp);
void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
int cpu, u64 *ts)
{
/* Just stupid testing the normalize function and deltas */
*ts >>= DEBUG_SHIFT;
}
EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp);
/**
* check_pages - integrity check of buffer pages
* @cpu_buffer: CPU buffer with pages to test
......@@ -569,6 +571,7 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags)
buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);
buffer->flags = flags;
buffer->clock = trace_clock_local;
/* need at least two pages */
if (buffer->pages == 1)
......@@ -645,6 +648,12 @@ ring_buffer_free(struct ring_buffer *buffer)
}
EXPORT_SYMBOL_GPL(ring_buffer_free);
void ring_buffer_set_clock(struct ring_buffer *buffer,
u64 (*clock)(void))
{
buffer->clock = clock;
}
static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer);
static void
......@@ -1191,7 +1200,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
cpu_buffer->tail_page = next_page;
/* reread the time stamp */
*ts = ring_buffer_time_stamp(cpu_buffer->cpu);
*ts = ring_buffer_time_stamp(buffer, cpu_buffer->cpu);
cpu_buffer->tail_page->page->time_stamp = *ts;
}
......@@ -1334,7 +1343,7 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000))
return NULL;
ts = ring_buffer_time_stamp(cpu_buffer->cpu);
ts = ring_buffer_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu);
/*
* Only the first commit can update the timestamp.
......@@ -2051,7 +2060,8 @@ rb_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
case RINGBUF_TYPE_DATA:
if (ts) {
*ts = cpu_buffer->read_stamp + event->time_delta;
ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts);
ring_buffer_normalize_time_stamp(buffer,
cpu_buffer->cpu, ts);
}
return event;
......@@ -2112,7 +2122,8 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
case RINGBUF_TYPE_DATA:
if (ts) {
*ts = iter->read_stamp + event->time_delta;
ring_buffer_normalize_time_stamp(cpu_buffer->cpu, ts);
ring_buffer_normalize_time_stamp(buffer,
cpu_buffer->cpu, ts);
}
return event;
......
......@@ -155,13 +155,6 @@ ns2usecs(cycle_t nsec)
return nsec;
}
cycle_t ftrace_now(int cpu)
{
u64 ts = ring_buffer_time_stamp(cpu);
ring_buffer_normalize_time_stamp(cpu, &ts);
return ts;
}
/*
* The global_trace is the descriptor that holds the tracing
* buffers for the live tracing. For each CPU, it contains
......@@ -178,6 +171,20 @@ static struct trace_array global_trace;
static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
cycle_t ftrace_now(int cpu)
{
u64 ts;
/* Early boot up does not have a buffer yet */
if (!global_trace.buffer)
return trace_clock_local();
ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
return ts;
}
/*
* The max_tr is used to snapshot the global_trace when a maximum
* latency is reached. Some tracers will use this to store a maximum
......
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