linux-kernel - [PATCH] printk: Print cpuid along with the timestamp with CONFIG_PRINTK

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Date:	Thu, 18 Sep 2008 12:37:20 -0700
From:	Ravikiran G Thirumalai <kiran@...lex86.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] printk: Print cpuid along with the timestamp with
	CONFIG_PRINTK_TIME

I found it useful to have the cpuid of the printing cpu along with the
timestamp -- especially while debugging hangs during bootups.

I don't know why this hasn't been implemened in the kernel yet, and
cannot think of a strong reason not to have it.  Yes, the cpuid prefix will
take 5 more characters per line,  but having  the cpuid info is worth it,
I think.

Thanks,
Kiran

---


Add cpuid information to printk if CONFIG_PRINTK_TIME is enabled.
This information is useful to debug hangs and bootup issues.

Signed-off-by: Ravikiran Thirumalai <kiran@...lex86.org>

Index: linux-git/kernel/printk.c
===================================================================
--- linux-git.orig/kernel/printk.c	2008-09-16 15:37:48.000000000 -0700
+++ linux-git/kernel/printk.c	2008-09-18 12:27:10.489662938 -0700
@@ -739,9 +739,10 @@ asmlinkage int vprintk(const char *fmt, 
 
 				t = cpu_clock(printk_cpu);
 				nanosec_rem = do_div(t, 1000000000);
-				tlen = sprintf(tbuf, "[%5lu.%06lu] ",
+				tlen = sprintf(tbuf, "[%5lu.%06lu:%d] ",
 						(unsigned long) t,
-						nanosec_rem / 1000);
+						nanosec_rem / 1000,
+						printk_cpu);
 
 				for (tp = tbuf; tp < tbuf + tlen; tp++)
 					emit_log_char(*tp);
--
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