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timeval: Coalesce backtraces with counts.

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With this patch, `ovs-appctl backtrace` will return a unique list
of backtraces and a count of how many times it has been recorded.
This work had previously been done by ovs-parse-backtrace. However,
in future patches poll-loop will begin logging backtraces as a
matter of course.  At this point, coalescing the backtraces will
help keep these log messages brief.

Signed-off-by: Ethan Jackson <ethan@nicira.com>
This commit is contained in:
Ethan Jackson
2012-10-22 15:42:31 -07:00
parent fdce775cc5
commit 7d1563e961
2 changed files with 79 additions and 28 deletions
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81
lib/timeval.c
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@@ -32,15 +32,13 @@
#include "dummy.h"
#include "dynamic-string.h"
#include "fatal-signal.h"
#include "hash.h"
#include "hmap.h"
#include "signals.h"
#include "unixctl.h"
#include "util.h"
#include "vlog.h"
#ifndef HAVE_EXECINFO_H
#define HAVE_EXECINFO_H 0
#endif
VLOG_DEFINE_THIS_MODULE(timeval);
/* The clock to use for measuring time intervals. This is CLOCK_MONOTONIC by
@@ -72,6 +70,10 @@ static long long int deadline = LLONG_MAX;
struct trace {
void *backtrace[32]; /* Populated by backtrace(). */
size_t n_frames; /* Number of frames in 'backtrace'. */
/* format_backtraces() helper data. */
struct hmap_node node;
size_t count;
};
#define MAX_TRACES 50
@@ -92,6 +94,22 @@ static void timespec_add(struct timespec *sum,
const struct timespec *a, const struct timespec *b);
static unixctl_cb_func backtrace_cb;
#ifndef HAVE_EXECINFO_H
#define HAVE_EXECINFO_H 0
static int
backtrace(void **buffer OVS_UNUSED, int size OVS_UNUSED)
{
NOT_REACHED();
}
static char **
backtrace_symbols(void *const *buffer OVS_UNUSED, int size OVS_UNUSED)
{
NOT_REACHED();
}
#endif
/* Initializes the timetracking module, if not already initialized. */
static void
time_init(void)
@@ -392,15 +410,13 @@ sigalrm_handler(int sig_nr OVS_UNUSED)
wall_tick = true;
monotonic_tick = true;
#if HAVE_EXECINFO_H
if (CACHE_TIME) {
if (HAVE_EXECINFO_H && CACHE_TIME) {
struct trace *trace = &traces[trace_head];
trace->n_frames = backtrace(trace->backtrace,
ARRAY_SIZE(trace->backtrace));
trace_head = (trace_head + 1) % MAX_TRACES;
}
#endif
}
static void
@@ -577,13 +593,37 @@ get_cpu_usage(void)
return cpu_usage;
}
static uint32_t
hash_trace(struct trace *trace)
{
return hash_bytes(trace->backtrace,
trace->n_frames * sizeof *trace->backtrace, 0);
}
static struct trace *
trace_map_lookup(struct hmap *trace_map, struct trace *key)
{
struct trace *value;
HMAP_FOR_EACH_WITH_HASH (value, node, hash_trace(key), trace_map) {
if (key->n_frames == value->n_frames
&& !memcmp(key->backtrace, value->backtrace,
key->n_frames * sizeof *key->backtrace)) {
return value;
}
}
return NULL;
}
static void
format_backtraces(struct ds *ds)
{
time_init();
#if HAVE_EXECINFO_H
if (CACHE_TIME) {
if (HAVE_EXECINFO_H && CACHE_TIME) {
struct hmap trace_map = HMAP_INITIALIZER(&trace_map);
struct trace *trace, *next;
sigset_t oldsigs;
size_t i;
@@ -591,16 +631,30 @@ format_backtraces(struct ds *ds)
for (i = 0; i < MAX_TRACES; i++) {
struct trace *trace = &traces[i];
char **frame_strs;
size_t j;
struct trace *map_trace;
if (!trace->n_frames) {
continue;
}
map_trace = trace_map_lookup(&trace_map, trace);
if (map_trace) {
map_trace->count++;
} else {
hmap_insert(&trace_map, &trace->node, hash_trace(trace));
trace->count = 1;
}
}
HMAP_FOR_EACH_SAFE (trace, next, node, &trace_map) {
char **frame_strs;
size_t j;
hmap_remove(&trace_map, &trace->node);
frame_strs = backtrace_symbols(trace->backtrace, trace->n_frames);
ds_put_format(ds, "Backtrace %zu\n", i + 1);
ds_put_format(ds, "Count %zu\n", trace->count);
for (j = 0; j < trace->n_frames; j++) {
ds_put_format(ds, "%s\n", frame_strs[j]);
}
@@ -608,10 +662,11 @@ format_backtraces(struct ds *ds)
free(frame_strs);
}
hmap_destroy(&trace_map);
ds_chomp(ds, '\n');
unblock_sigalrm(&oldsigs);
}
#endif
}
/* Unixctl interface. */