enhance initcall_debug, measure latency

enhance the initcall_debug boot option:

 - measure the time the initcall took to execute and report
   it in units of milliseconds.

 - show the return code of initcalls (useful to see failures and
   to make sure that an initcall hung)

[akpm@linux-foundation.org: fix printk warning]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/init/main.c b/init/main.c
index 949c27b59d126b448cb113946d1a635328db8664..c1537e0ddcebdc549d4b5d426640e81e878cff79 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -648,6 +648,7 @@ static void __init do_initcalls(void)
        int count = preempt_count();
 
        for (call = __initcall_start; call < __initcall_end; call++) {
+               ktime_t t0, t1, delta;
                char *msg = NULL;
                char msgbuf[40];
                int result;
@@ -657,10 +658,26 @@ static void __init do_initcalls(void)
                        print_fn_descriptor_symbol(": %s()",
                                        (unsigned long) *call);
                        printk("\n");
+                       t0 = ktime_get();
                }
 
                result = (*call)();
 
+               if (initcall_debug) {
+                       t1 = ktime_get();
+                       delta = ktime_sub(t1, t0);
+
+                       printk("initcall 0x%p", *call);
+                       print_fn_descriptor_symbol(": %s()",
+                                       (unsigned long) *call);
+                       printk(" returned %d.\n", result);
+
+                       printk("initcall 0x%p ran for %Ld msecs: ",
+                               *call, (unsigned long long)delta.tv64 >> 20);
+                       print_fn_descriptor_symbol("%s()\n",
+                               (unsigned long) *call);
+               }
+
                if (result && result != -ENODEV && initcall_debug) {
                        sprintf(msgbuf, "error code %d", result);
                        msg = msgbuf;