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ftrace: add logic to record overruns

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This patch sets up the infrastructure to record overruns of the tracing
buffer.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Steven Rostedt 2008-05-12 21:21:01 +02:00 committed by Thomas Gleixner
parent 72b59d67f8
commit 53d0aa7730
2 changed files with 16 additions and 6 deletions
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16
kernel/trace/trace.c
View File

@ -609,6 +609,7 @@ void unregister_tracer(struct tracer *type)
void tracing_reset(struct trace_array_cpu *data)
{
data->trace_idx = 0;
data->overrun = 0;
data->trace_head = data->trace_tail = head_page(data);
data->trace_head_idx = 0;
data->trace_tail_idx = 0;
@ -750,6 +751,7 @@ tracing_get_trace_entry(struct trace_array *tr, struct trace_array_cpu *data)
if (data->trace_head == data->trace_tail &&
idx_next == data->trace_tail_idx) {
/* overrun */
data->overrun++;
data->trace_tail_idx++;
if (data->trace_tail_idx >= ENTRIES_PER_PAGE) {
data->trace_tail =
@ -2353,8 +2355,6 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
{
struct trace_iterator *iter = filp->private_data;
struct trace_array_cpu *data;
struct trace_array *tr = iter->tr;
struct tracer *tracer = iter->trace;
static cpumask_t mask;
static int start;
unsigned long flags;
@ -2433,10 +2433,11 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
if (cnt >= PAGE_SIZE)
cnt = PAGE_SIZE - 1;
memset(iter, 0, sizeof(*iter));
iter->tr = tr;
iter->trace = tracer;
/* reset all but tr, trace, and overruns */
iter->pos = -1;
memset(&iter->seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
/*
* We need to stop all tracing on all CPUS to read the
@ -2465,6 +2466,11 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
for_each_cpu_mask(cpu, mask) {
data = iter->tr->data[cpu];
__raw_spin_lock(&data->lock);
if (data->overrun > iter->last_overrun[cpu])
iter->overrun[cpu] +=
data->overrun - iter->last_overrun[cpu];
iter->last_overrun[cpu] = data->overrun;
}
while (find_next_entry_inc(iter) != NULL) {

6
kernel/trace/trace.h
View File

@ -97,6 +97,7 @@ struct trace_array_cpu {
void *trace_head; /* producer */
void *trace_tail; /* consumer */
unsigned long trace_idx;
unsigned long overrun;
unsigned long saved_latency;
unsigned long critical_start;
unsigned long critical_end;
@ -157,10 +158,13 @@ struct trace_seq {
* results to users and which routines might sleep, etc:
*/
struct trace_iterator {
struct trace_seq seq;
struct trace_array *tr;
struct tracer *trace;
long last_overrun[NR_CPUS];
long overrun[NR_CPUS];
/* The below is zeroed out in pipe_read */
struct trace_seq seq;
struct trace_entry *ent;
int cpu;