On Thu 2016-01-28 07:43:49, Prarit Bhargava wrote:
> +static u64 printk_get_ts(void)
> +{
> + u64 mono, offset_real;
> +
> + if (printk_time == 0)
> + return 0;
> +
> + if (printk_time == 1)
> + return local_clock();
> +
> + mono = ktime_get_log_ts(&offset_real);
> +
> + if (printk_time == 2)
> + return mono;
> +
> + return mono + offset_real;
At least dmesg is not capable to read the absolute size of the
real time. It expects offset against the start of the timekeeping
stuff or so. I get this:
$> dmesg | tail -n 5
[ 7.128924] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 0.000000] printk: timestamp set to 0.
[ 179.983704] printk: timestamp set to 1.
[ 181.895655] printk: timestamp set to 2.
[1454602412.026424] printk: timestamp set to 3.
$dmesg -T -S | tail -n 5
[Thu Feb 4 17:10:34 2016] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes
ready
[Thu Feb 4 17:10:27 2016] printk: timestamp set to 0.
[Thu Feb 4 17:13:26 2016] printk: timestamp set to 1.
[Thu Feb 4 17:13:28 2016] printk: timestamp set to 2.
[Fri Mar 10 09:23:59 2062] printk: timestamp set to 3.
Please, note that the last entry points to the year 2062.
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -13,7 +13,7 @@ config PRINTK_TIME
> be included, not that the timestamp is recorded.
>
> The behavior is also controlled by the kernel command line
> - parameter printk.time=1. See Documentation/kernel-parameters.txt
> + parameter printk.time=[0-3]. See Documentation/kernel-parameters.txt
Please, mention there the mention of the numbers. The cross reference
is annoying if you look at the help when configuring kernel build.
Also there is a mismatch between the values and the type of
CONFIG_PRINTK_TIME. You should change it to
int "Show timing information on printks"
range 0 3
Then you need to update the default value for all
architectures in all arch/*/configs/*_defconfig
It seems that it is enabled in most architectures. I would suggest
to define
default "1"
in lib/Kconfig.debug. Then you could remove the definition from
most defconfigs. The advantage is that even "make oldconfig"
will propose reasonable default.
Best Regards,
Petr
PS: Please, put version number to the subject, e.g. [PATCH v4].
It makes it slightly easier to orientate in the variants ;-)
