Re: How to disable tracing at runtime from the Linux kernel command line?

From: Steven Rostedt
Date: Sat Apr 14 2018 - 12:30:19 EST


On Sat, 14 Apr 2018 15:09:33 +0200
Paul Menzel <pmenzel+linux-tracing@xxxxxxxxxxxxx> wrote:

> Dear Linux folks,
>
>
> I am trying to reduce the boot time of a standard Linux distribution
> kernel. Currently, distributions â at least Debian und Ubuntu â enable
> function tracing.
>
> ```
> CONFIG_FTRACE=y
> CONFIG_FUNCTION_TRACER=y
> CONFIG_FUNCTION_GRAPH_TRACER=y
>
> CONFIG_EVENT_TRACING=y
> ```
>
> This is great, as it makes it easy to use tracing to hunt down things
> holding up the boot. But it also skews the boot time quite a lot.
>
> ```
> $ sudo dmesg
> [â]
> [ 0.318412] initcall init_graph_trace+0x0/0x64 returned 0 after
> 199218 usecs
> [â]
> [ 1.770287] calling event_trace_init+0x0/0x2c2 @ 1
> [ 2.052871] initcall event_trace_init+0x0/0x2c2 returned 0 after
> 275942 usecs
> [â]
> ```
>
> Is there a way to disable tracing on the Linux kernel command line to
> disable tracing?
>

Try initcall_blacklist. But you acquire all risks when doing so. I
never tried it, so I have no idea what side effects that may have.

-- Steve