Merge "Clarify a few things about bootcharts."

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;
 }

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
 --------------