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Date: Wed, 19 Jan 2011 17:01:12 -0600
From: Mike Travis <travis@sgi.com>
To: Ingo Molnar <mingo@elte.hu>, Len Brown <len.brown@intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Jack Steiner <steiner@sgi.com>,
	Robin Holt <holt@sgi.com>, Lori Gilbertson <loriann@sgi.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: [PATCH 6/6] printk: Minimize time zero output
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--- linux-2.6.32.orig/kernel/printk.c
+++ linux-2.6.32/kernel/printk.c
@@ -806,11 +806,14 @@ asmlinkage int vprintk(const char *fmt,
 				unsigned long nanosec_rem;
 
 				t = cpu_clock(printk_cpu);
-				nanosec_rem = do_div(t, 1000000000);
-				tlen = sprintf(tbuf, "[%5lu.%06lu] ",
+				if (likely(t)) {
+					nanosec_rem = do_div(t, 1000000000);
+					tlen = sprintf(tbuf, "[%5lu.%06lu] ",
 						(unsigned long) t,
 						nanosec_rem / 1000);
-
+				} else {
+					tlen = sprintf(tbuf, "[0] ");
+				}
 				for (tp = tbuf; tp < tbuf + tlen; tp++)
 					emit_log_char(*tp);
 				printed_len += tlen;