trace-graph: Limit the search back for task plots display data

The task plot was search every CPU for a matching event. If a CPU did
not have any events for a given plot, it would search all the way back to the
start!  This caused a huge delay in processing and would hang trace-graph
for seconds while it would search the cpu data backwards.

Limit the distance to only 5 pixels in its search.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 14 insertions, 3 deletions

diff --git a/trace-plot-task.c b/trace-plot-task.c
index ecbf873..c92adb9 100644
--- a/trace-plot-task.c
+++ b/trace-plot-task.c
@@ -377,7 +377,7 @@ task_plot_find_record(struct graph_info *ginfo, struct graph_plot *plot,
 
 static struct record *
 find_previous_record(struct graph_info *ginfo, struct record *start_record,
-                     int pid, int cpu)
+                     int pid, int cpu, unsigned long long time)
 {
         struct record *last_record = start_record;
         struct record *record;
@@ -399,6 +399,11 @@ find_previous_record(struct graph_info *ginfo, struct record *start_record,
 
                 if (last_record != start_record)
                         free_record(last_record);
+
+                if (record->ts < time) {
+                        free_record(record);
+                        return NULL;
+                }
                 last_record = record;
         }
 
@@ -414,6 +419,7 @@ get_display_record(struct graph_info *ginfo, int pid, unsigned long long time)
         struct record *record;
         struct record **records;
         unsigned long long ts;
+        unsigned long long limit;
         int next_cpu;
         int cpu;
 
@@ -429,11 +435,15 @@ get_display_record(struct graph_info *ginfo, int pid, unsigned long long time)
                 free_record(record);
         }
 
+        /* Only search 5 pixels back */
+        limit = time - (5 / ginfo->resolution);
+
         /* find a previous record */
         records = malloc_or_die(sizeof(*records) * ginfo->cpus);
         for (cpu = 0; cpu < ginfo->cpus; cpu++) {
                 record = tracecmd_read_data(ginfo->handle, cpu);
-                records[cpu] = find_previous_record(ginfo, record, pid, cpu);
+                records[cpu] = find_previous_record(ginfo, record,
+                                                    pid, cpu, limit);
                 free_record(record);
         }
 
@@ -459,7 +469,8 @@ get_display_record(struct graph_info *ginfo, int pid, unsigned long long time)
                         break;
                 }
 
-                record = find_previous_record(ginfo, records[next_cpu], pid, next_cpu);
+                record = find_previous_record(ginfo, records[next_cpu],
+                                              pid, next_cpu, limit);
                 free_record(records[next_cpu]);
                 records[next_cpu] = record;
                 record = NULL;