printk second output

When I printk(KERN_INFO, ...), I get something lik开发者_开发百科e this:

<6>[116584.000183] ...

What is the number between the square brackets exactly?

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Seconds since startup. You can control whether this is shown with the CONFIG_PRINTK_TIME variable in kernel config.

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It's a timestamp with microsecond resolution. See the printk source.