add st-draw: a pycairo based drawing tool for st_trace schedules

1 files changed, 58 insertions, 0 deletions

diff --git a/sched_trace/file.py b/sched_trace/file.py
new file mode 100644
index 0000000..5c18163
--- /dev/null
+++ b/sched_trace/file.py
@@ -0,0 +1,58 @@
+"""Convenience wrapper around mmap'ed sched_trace binary files.
+"""
+
+from .format import RECORD_LEN, unpack, get_event, EVENTS
+
+import mmap
+
+class SchedTraceFile(object):
+    def __init__(self, fname):
+        self.source = fname
+        with open(fname, 'rw') as f:
+            self.mem = mmap.mmap(f.fileno(), 0, mmap.MAP_PRIVATE)
+
+    def __len__(self):
+        return len(self.mem) / RECORD_LEN
+
+    def events_of_type(self, event_ids):
+        for i in xrange(len(self)):
+            if get_event(self.mem, i) in event_ids:
+                record = self.mem[i * RECORD_LEN:]
+                yield unpack(record)
+
+    def __iter__(self):
+        for i in xrange(len(self)):
+            record = self.mem[i * RECORD_LEN:]
+            yield unpack(record)
+
+    def __reversed__(self):
+        for i in reversed(xrange(len(self))):
+            record = self.mem[i * RECORD_LEN:]
+            yield unpack(record)
+
+    def raw_iter(self):
+        for i in xrange(len(self)):
+            record = self.mem[i * RECORD_LEN:(i + 1) * RECORD_LEN]
+            yield record
+
+    def scheduling_intervals(self):
+        to_id = EVENTS['ST_SWITCH_TO']
+        away_id = EVENTS['ST_SWITCH_AWAY']
+
+        # assumption: we are looking at a per-CPU trace
+        events = self.events_of_type(set((to_id, away_id)))
+
+        rec = events.next()
+        while True:
+            # fast-forward to next SWITCH_TO
+            while rec[0] != to_id:
+                rec = events.next()
+
+            to = rec
+            # next one on this CPU should be a SWITCH_AWAY
+            rec = events.next()
+            away = rec
+            # check for event ID and matching PID and CPU and monotonic time
+            if away[0] == away_id and away[1] == to[1] and away[2] == to[2] \
+               and to[4] <= away[4]:
+                yield (to, away)