On Tue, 2006-08-08 at 18:59 +0200, Jan Kiszka wrote:
> Hi,
>
> this tiny patch adds a config option to I-pipe to allow starting the
> system with the tracer compiled in but disabled. You can then enabled it
> on demand via /proc/ipipe/tracer/enable. This saves a bit time when
> booting low-end boxes (I wonder why I didn't hacked this earlier...).
>
Merged, thanks.
> Jan
> plain text document attachment (tracer-default-off.patch)
> Index: linux-2.6.17.8/kernel/ipipe/Kconfig
> ===================================================================
> --- linux-2.6.17.8.orig/kernel/ipipe/Kconfig
> +++ linux-2.6.17.8/kernel/ipipe/Kconfig
> @@ -6,7 +6,7 @@ config IPIPE
> compiled in.
>
> config IPIPE_TRACE
> - bool "Latency Tracing"
> + bool "Latency tracing"
> depends on IPIPE && PROC_FS
> select FRAME_POINTER
> default n
> @@ -18,6 +18,15 @@ config IPIPE_TRACE
> in-kernel tracing API. The collected data and runtime control
> is available via /proc/ipipe/trace/*.
>
> +config IPIPE_TRACE_ENABLE
> + bool "Enable tracing on boot"
> + depends on IPIPE_TRACE
> + default y
> + ---help---
> + Disable this option if you want to arm the tracer after booting
> + manually ("echo 1 > /proc/ipipe/tracer/enable"). This can reduce
> + boot time on slow embedded devices due to the tracer overhead.
> +
> config IPIPE_TRACE_IRQSOFF
> bool "Trace IRQs-off times"
> depends on IPIPE_TRACE
> @@ -44,3 +53,8 @@ config IPIPE_TRACE_VMALLOC
> enabled. This can help to start systems that are low on memory,
> but it slightly degrades overall performance. Try this option
> when a traced kernel hangs unexpectedly at boot time.
> +
> +config IPIPE_TRACE_ENABLE_VALUE
> + int
> + default 0 if !IPIPE_TRACE_ENABLE
> + default 1 if IPIPE_TRACE_ENABLE
> Index: linux-2.6.17.8/kernel/ipipe/tracer.c
> ===================================================================
> --- linux-2.6.17.8.orig/kernel/ipipe/tracer.c
> +++ linux-2.6.17.8/kernel/ipipe/tracer.c
> @@ -105,7 +105,7 @@ enum ipipe_trace_type
> static struct ipipe_trace_path *trace_paths[NR_CPUS];
>
> #else /* !CONFIG_IPIPE_TRACE_VMALLOC */
> -#define IPIPE_DEFAULT_TRACE_STATE 1
> +#define IPIPE_DEFAULT_TRACE_STATE CONFIG_IPIPE_TRACE_ENABLE_VALUE
>
> static struct ipipe_trace_path trace_paths[NR_CPUS][IPIPE_TRACE_PATHS] =
> { [0 ... NR_CPUS-1] =
> @@ -1217,7 +1217,7 @@ void __init __ipipe_init_tracer(void)
> trace_paths[cpu][path].end = -1;
> }
> }
> - ipipe_trace_enable = 1;
> + ipipe_trace_enable = CONFIG_IPIPE_TRACE_ENABLE_VALUE;
> #endif /* CONFIG_IPIPE_TRACE_VMALLOC */
>
> trace_dir = create_proc_entry("trace", S_IFDIR, ipipe_proc_root);
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--
Philippe.
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