Compare two bootcharts and list timestamps for selected processes.
Usage: system/core/init/compare-bootcharts.py base_bootchart_dir
exp_bootchart_dir
For example, here is the output where the bootanimation is changed
from "d 0 0 part2" to "c 0 0 part2":
--
process: baseline experiment (delta)
- Unit is ms (a jiffy is 10 ms on the system)
------------------------------------
/init: 50 40 (-10)
/system/bin/surfaceflinger: 4320 4470 (+150)
/system/bin/bootanimation: 6980 6990 (+10)
zygote64: 10410 10640 (+230)
zygote: 10410 10640 (+230)
system_server: 15350 15150 (-200)
bootanimation ends at: 33790 31230 (-2560)
--
In this example bootanimation is finished (estimated) 2.56 seconds sooner.
Change-Id: I39d59897c8c53d7d662676813e884b9d58feec3c
diff --git a/init/readme.txt b/init/readme.txt
index c213041..4cbe600 100644
--- a/init/readme.txt
+++ b/init/readme.txt
@@ -347,6 +347,29 @@
actually started init.
+Comparing two bootcharts
+------------------------
+A handy script named compare-bootcharts.py can be used to compare the
+start/end time of selected processes. The aforementioned grab-bootchart.sh
+will leave a bootchart tarball named bootchart.tgz at /tmp/android-bootchart.
+If two such barballs are preserved on the host machine under different
+directories, the script can list the timestamps differences. For example:
+
+Usage: system/core/init/compare-bootcharts.py base_bootchart_dir
+ exp_bootchart_dir
+
+process: baseline experiment (delta)
+ - Unit is ms (a jiffy is 10 ms on the system)
+------------------------------------
+/init: 50 40 (-10)
+/system/bin/surfaceflinger: 4320 4470 (+150)
+/system/bin/bootanimation: 6980 6990 (+10)
+zygote64: 10410 10640 (+230)
+zygote: 10410 10640 (+230)
+system_server: 15350 15150 (-200)
+bootanimation ends at: 33790 31230 (-2560)
+
+
Debugging init
--------------
By default, programs executed by init will drop stdout and stderr into