Clarify a few things about bootcharts.

Make it clearer in dmesg when we're deliberately not doing
bootcharting, and explain in the documentation that the output
for init is quite misleading (and, as far as I can tell, not
within our power to fix).

Change-Id: I0b22a56f83521d64c6d176dc423c81f7ea86b23c

2 files changed, 13 insertions, 14 deletions

diff --git a/init/bootchart.cpp b/init/bootchart.cpp
index 03c8b30..95687cb 100644
--- a/init/bootchart.cpp
+++ b/init/bootchart.cpp
@@ -195,13 +195,8 @@ static int bootchart_init() {
     }
 
     // Create kernel process accounting file.
-    {
-        int  fd = open( LOG_ACCT, O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC,0644);
-        if (fd >= 0) {
-            close(fd);
-            acct( LOG_ACCT );
-        }
-    }
+    close(open(LOG_ACCT, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644));
+    acct(LOG_ACCT);
 
     log_header();
     return count;
@@ -210,11 +205,12 @@ static int bootchart_init() {
 int do_bootchart_init(int nargs, char** args) {
     g_remaining_samples = bootchart_init();
     if (g_remaining_samples < 0) {
-        ERROR("bootcharting init failure: %s\n", strerror(errno));
+        ERROR("Bootcharting init failure: %s\n", strerror(errno));
     } else if (g_remaining_samples > 0) {
-        NOTICE("bootcharting started (will run for %d ms)\n", g_remaining_samples*BOOTCHART_POLLING_MS);
+        NOTICE("Bootcharting started (will run for %d s).\n",
+               (g_remaining_samples * BOOTCHART_POLLING_MS) / 1000);
     } else {
-        NOTICE("bootcharting ignored\n");
+        NOTICE("Not bootcharting.\n");
     }
     return 0;
 }
diff --git a/init/readme.txt b/init/readme.txt
index 4c8d0d3..630dd03 100644
--- a/init/readme.txt
+++ b/init/readme.txt
@@ -323,12 +323,11 @@ init.svc.<name>
 
 Bootcharting
 ------------
-
 This version of init contains code to perform "bootcharting": generating log
 files that can be later processed by the tools provided by www.bootchart.org.
 
-On the emulator, use the new -bootchart <timeout> option to boot with
-bootcharting activated for <timeout> seconds.
+On the emulator, use the -bootchart <timeout> option to boot with bootcharting
+activated for <timeout> seconds.
 
 On a device, create /data/bootchart/start with a command like the following:
 
@@ -349,9 +348,13 @@ retrieve them and create a bootchart.tgz file that can be used with the
 bootchart command-line utility:
 
   sudo apt-get install pybootchartgui
-  ANDROID_SERIAL=<device serial number>
+  # grab-bootchart.sh uses $ANDROID_SERIAL.
   $ANDROID_BUILD_TOP/system/core/init/grab-bootchart.sh
 
+One thing to watch for is that the bootchart will show init as if it started
+running at 0s. You'll have to look at dmesg to work out when the kernel
+actually started init.
+
 
 Debugging init
 --------------