[PATCH] stopwatch usage may misorder first event

If the stopwatch_start happens to trigger when we only have
events from _some_ of the available cpus in the rb_sort tree,
the first event may be misreported. Check for that.

diff --git a/blkparse.c b/blkparse.c
index c30ac96e60310cb50e9dcbf4f2037795514bd958..a834278be127bc9d11cb9635cf24f5ea65ecff1d 100644 (file)
--- a/blkparse.c
+++ b/blkparse.c
@@ -55,6 +55,7 @@ struct per_dev_info {
        struct rb_root rb_track;
 
        int nfiles;
+       int nopenfiles;
        int ncpus;
        struct per_cpu_info *cpus;
 };
@@ -1305,6 +1306,9 @@ static int sort_entries(unsigned long long *youngest)
                if (bit->time < *youngest || !*youngest)
                        *youngest = bit->time;
 
+               if (bit->sequence < smallest_seq_read)
+                       smallest_seq_read = bit->sequence;
+
                if (check_stopwatch(bit)) {
                        bit_free(bit);
                        t_free(t);
@@ -1313,9 +1317,6 @@ static int sort_entries(unsigned long long *youngest)
 
                if (trace_rb_insert_sort(t))
                        return -1;
-
-               if (bit->sequence < smallest_seq_read)
-                       smallest_seq_read = bit->sequence;
        }
 
        return 0;
@@ -1351,11 +1352,37 @@ static int check_sequence(struct per_dev_info *pdi, struct trace *t, int force)
        struct blk_io_trace *bit = t->bit;
        struct trace *__t;
        
-       /*
-        * first entry, always ok
-        */
-       if (!expected_sequence)
-               return 0;
+       if (!expected_sequence) {
+               struct rb_node *n;
+               char *cpu_seen;
+               int cpus;
+
+               /*
+                * 1 should be the first entry, just allow it
+                */
+               if (bit->sequence == 1)
+                       return 0;
+
+               /*
+                * if we are starting somewhere else, check that we have
+                * entries from all cpus in the tree before dumping one
+                */
+               cpu_seen = malloc(pdi->nopenfiles);
+               n = rb_first(&rb_sort_root);
+               cpus = 0;
+               while (n) {
+                       __t = rb_entry(n, struct trace, rb_node);
+
+                       if (!cpu_seen[__t->bit->cpu]) {
+                               cpu_seen[__t->bit->cpu] = 1;
+                               cpus++;
+                       }
+                       n = rb_next(n);
+               }
+
+               free(cpu_seen);
+               return cpus != pdi->nopenfiles;
+       }
 
        if (bit->sequence == expected_sequence)
                return 0;
@@ -1560,6 +1587,7 @@ static int do_file(void)
 
                        printf("Input file %s added\n", pci->fname);
                        pdi->nfiles++;
+                       pdi->nopenfiles++;
                }
        }
 
@@ -1587,6 +1615,7 @@ static int do_file(void)
                                if (!events) {
                                        close(pci->fd);
                                        pci->fd = -1;
+                                       pdi->nopenfiles--;
                                        continue;
                                }