X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Ftimeval.c;h=d91305c679cb7fbe7c99c7b425b062a37a146d19;hb=ea7655d9f9d38a3af7250de8ba0b89115b5f4a5e;hp=e5071403227f111c56fa8d5e95b8e3ebb0138fa1;hpb=fdce775cc57314913b663c3efbdce25cdf61591e;p=sliver-openvswitch.git

diff --git a/lib/timeval.c b/lib/timeval.c
index e50714032..d91305c67 100644
--- a/lib/timeval.c
+++ b/lib/timeval.c
@@ -16,7 +16,6 @@
 
 #include <config.h>
 #include "timeval.h"
-#include <assert.h>
 #include <errno.h>
 #if HAVE_EXECINFO_H
 #include <execinfo.h>
@@ -32,15 +31,13 @@
 #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 +69,10 @@ 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 +93,22 @@ 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)
@@ -103,6 +120,16 @@ time_init(void)
     }
     inited = true;
 
+    /* The implementation of backtrace() in glibc does some one time
+     * initialization which is not signal safe.  This can cause deadlocks if
+     * run from the signal handler.  As a workaround, force the initialization
+     * to happen here. */
+    if (HAVE_EXECINFO_H) {
+        void *bt[1];
+
+        backtrace(bt, ARRAY_SIZE(bt));
+    }
+
     memset(traces, 0, sizeof traces);
 
     if (HAVE_EXECINFO_H && CACHE_TIME) {
@@ -392,15 +419,13 @@ 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 +602,40 @@ get_cpu_usage(void)
     return cpu_usage;
 }
 
-static void
-format_backtraces(struct ds *ds)
+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;
+}
+
+/*  Appends a string to 'ds' representing backtraces recorded at regular
+ *  intervals in the recent past.  This information can be used to get a sense
+ *  of what the process has been spending the majority of time doing.  Will
+ *  ommit any backtraces which have not occurred at least 'min_count' times. */
+void
+format_backtraces(struct ds *ds, size_t min_count)
 {
     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 +643,34 @@ format_backtraces(struct ds *ds)
 
         for (i = 0; i < MAX_TRACES; i++) {
             struct trace *trace = &traces[i];
+            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;
 
-            if (!trace->n_frames) {
+            hmap_remove(&trace_map, &trace->node);
+
+            if (trace->count < min_count) {
                 continue;
             }
 
             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 +678,11 @@ format_backtraces(struct ds *ds)
 
             free(frame_strs);
         }
+        hmap_destroy(&trace_map);
+
         ds_chomp(ds, '\n');
         unblock_sigalrm(&oldsigs);
     }
-#endif
 }
 
 /* Unixctl interface. */
@@ -659,8 +730,8 @@ backtrace_cb(struct unixctl_conn *conn,
 {
     struct ds ds = DS_EMPTY_INITIALIZER;
 
-    assert(HAVE_EXECINFO_H && CACHE_TIME);
-    format_backtraces(&ds);
+    ovs_assert(HAVE_EXECINFO_H && CACHE_TIME);
+    format_backtraces(&ds, 0);
     unixctl_command_reply(conn, ds_cstr(&ds));
     ds_destroy(&ds);
 }