[PATCH 1/4] tracepoint: add generic tracepoint definitions for IPI tracing

[Daniel Lezcano]

On 07/18/2014 07:18 AM, Nicolas Pitre wrote:
> The Inter Processor Interrupt is used to make another processor do a
> specific action such as rescheduling tasks, signal a timer event or
> execute something in another CPU's context. IRQs are already traceable
> but IPIs were not. Tracing them is useful for monitoring IPI latency,
> or to verify when they are the source of CPU wake-ups with power
> management implications.
>
> Three trace hooks are defined: ipi_raise, ipi_entry and ipi_exit. To make
> them portable, a string is used to identify them and correlate related
> events. Additionally, ipi_raise records a bitmask representing targeted
> CPUs.
>
> Signed-off-by: Nicolas Pitre <nico at linaro.org>

Acked-by: Daniel Lezcano <daniel.lezcano at linaro.org>



> ---
>   include/trace/events/ipi.h | 89 ++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 89 insertions(+)
>   create mode 100644 include/trace/events/ipi.h
>
> diff --git a/include/trace/events/ipi.h b/include/trace/events/ipi.h
> new file mode 100644
> index 0000000000..834a7362a6
> --- /dev/null
> +++ b/include/trace/events/ipi.h
> @@ -0,0 +1,89 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM ipi
> +
> +#if !defined(_TRACE_IPI_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_IPI_H
> +
> +#include <linux/tracepoint.h>
> +
> +/**
> + * ipi_raise - called when a smp cross call is made
> + *
> + * @mask: mask of recipient CPUs for the IPI
> + * @reason: string identifying the IPI purpose
> + *
> + * It is necessary for @reason to be a static string declared with
> + * __tracepoint_string.
> + */
> +TRACE_EVENT(ipi_raise,
> +
> +	TP_PROTO(const struct cpumask *mask, const char *reason),
> +
> +	TP_ARGS(mask, reason),
> +
> +	TP_STRUCT__entry(
> +		__bitmask(target_cpus, nr_cpumask_bits)
> +		__field(const char *, reason)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_bitmask(target_cpus, cpumask_bits(mask), nr_cpumask_bits);
> +		__entry->reason = reason;
> +	),
> +
> +	TP_printk("target_mask=%s (%s)", __get_bitmask(target_cpus), __entry->reason)
> +);
> +
> +DECLARE_EVENT_CLASS(ipi_handler,
> +
> +	TP_PROTO(const char *reason),
> +
> +	TP_ARGS(reason),
> +
> +	TP_STRUCT__entry(
> +		__field(const char *, reason)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->reason = reason;
> +	),
> +
> +	TP_printk("(%s)", __entry->reason)
> +);
> +
> +/**
> + * ipi_entry - called immediately before the IPI handler
> + *
> + * @reason: string identifying the IPI purpose
> + *
> + * It is necessary for @reason to be a static string declared with
> + * __tracepoint_string, ideally the same as used with trace_ipi_raise
> + * for that IPI.
> + */
> +DEFINE_EVENT(ipi_handler, ipi_entry,
> +
> +	TP_PROTO(const char *reason),
> +
> +	TP_ARGS(reason)
> +);
> +
> +/**
> + * ipi_exit - called immediately after the IPI handler returns
> + *
> + * @reason: string identifying the IPI purpose
> + *
> + * It is necessary for @reason to be a static string declared with
> + * __tracepoint_string, ideally the same as used with trace_ipi_raise for
> + * that IPI.
> + */
> +DEFINE_EVENT(ipi_handler, ipi_exit,
> +
> +	TP_PROTO(const char *reason),
> +
> +	TP_ARGS(reason)
> +);
> +
> +#endif /* _TRACE_IPI_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
>


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