Re: [PATCH 5/6] printk: Minimize time zero output

[David Rientjes]

On Fri, 18 Feb 2011, Mike Travis wrote:

> Reduce the length for time zero messages by only printing "[0] ".
> 
> v2: updated to apply to x86-tip
> 
> Signed-off-by: Mike Travis <travis@xxxxxxx>
> Reviewed-by: Jack Steiner <steiner@xxxxxxx>
> Reviewed-by: Robin Holt <holt@xxxxxxx>
> ---
>  kernel/printk.c |   11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> --- linux.orig/kernel/printk.c
> +++ linux/kernel/printk.c
> @@ -735,9 +735,14 @@ static inline int printk_emit_time(void)
>  	unsigned long microsec_rem;
>  
>  	t = cpu_clock(printk_cpu);
> -	microsec_rem = do_div(t, 1000000000) / 1000;
> -	tlen = sprintf(tbuf, "[%5lu.%06lu] ", (unsigned long)t, microsec_rem);
> -
> +	if (likely(t)) {
> +		microsec_rem = do_div(t, 1000000000) / 1000;
> +		tlen = sprintf(tbuf, "[%5lu.%06lu] ",
> +					(unsigned long)t, microsec_rem);

The definition of microsec_rem can become local to this clause.

> +	} else {
> +		/* reduce byte count in log when time is zero */
> +		tlen = sprintf(tbuf, "[0] ");

If we know the padding when cpu_clock() is non-zero, then why not make 
sure the kernel log is aligned properly by using the same padding here?

> +	}
>  	for (tp = tbuf; tp < tbuf + tlen; tp++)
>  		emit_log_char(*tp);
>  
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/