linux-kernel - Re: [PATCH 3/3] add irq tracepoint documentation

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Date:	Wed, 29 Apr 2009 12:09:50 -0700
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	Jason Baron <jbaron@...hat.com>
CC:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	mingo@...e.hu, rostedt@...dmis.org, fweisbec@...il.com,
	mathieu.desnoyers@...ymtl.ca, wcohen@...hat.com
Subject: Re: [PATCH 3/3] add irq tracepoint documentation

Jason Baron wrote:
> Document irqs for the newly created docbook.
> 
> Signed-off-by: Jason Baron <jbaron@...hat.com>
> 
> ---
>  Documentation/DocBook/tracepoint.tmpl |    5 +++
>  include/trace/events/irq.h            |   46 ++++++++++++++++++++++++++++++---
>  2 files changed, 47 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl
> index 2639a8b..8b7fb48 100644
> --- a/Documentation/DocBook/tracepoint.tmpl
> +++ b/Documentation/DocBook/tracepoint.tmpl
> @@ -81,4 +81,9 @@
>     </para>
>    </chapter>
>  
> +  <chapter id="irq">
> +   <title>IRQ</title>
> +!Iinclude/trace/events/irq.h
> +  </chapter>
> +
>  </book>
> diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
> index 7686864..bb5bbec 100644
> --- a/include/trace/events/irq.h
> +++ b/include/trace/events/irq.h
> @@ -7,8 +7,16 @@
>  #undef TRACE_SYSTEM
>  #define TRACE_SYSTEM irq
>  
> -/*
> - * Tracepoint for entry of interrupt handler:
> +/**
> + * irq_handler_entry - called immediately before the irq action handler
> + * @irq: irq number
> + * @action: pointer to struct irqaction
> + *
> + * The struct irqaction pointed to by the 'action' parameter contains

Parameters are usually written as:           @action
etc....

Otherwise looks good.  Thanks.

Acked-by: Randy Dunlap <randy.dunlap@...cle.com>


> + * various information about the handler, including the device name,
> + * action->name, and the device id, action->dev_id. When used in
> + * conjunction with the irq_handler_exit tracepoint, we can figure
> + * out irq handler latencies.
>   */
>  TRACE_EVENT(irq_handler_entry,
>  
> @@ -29,8 +37,16 @@ TRACE_EVENT(irq_handler_entry,
>  	TP_printk("irq=%d handler=%s", __entry->irq, __get_str(name))
>  );
>  
> -/*
> - * Tracepoint for return of an interrupt handler:
> +/**
> + * irq_handler_exit - called immediately after the irq action handler returns
> + * @irq: irq number
> + * @action: pointer to struct irqaction
> + * @ret: return value
> + *
> + * If the 'ret' value is set to IRQ_HANDLED, then we know that the corresponding
> + * action->handler scuccessully handled this irq. Otherwise, the irq might be
> + * a shared irq line, or the irq was not handled successfully. Can be used in
> + * conjunction with the irq_handler_entry to understand irq handler latencies.
>   */
>  TRACE_EVENT(irq_handler_exit,
>  
> @@ -52,6 +68,17 @@ TRACE_EVENT(irq_handler_exit,
>  		  __entry->irq, __entry->ret ? "handled" : "unhandled")
>  );
>  
> +/**
> + * softirq_entry - called immediately before the softirq handler
> + * @h: pointer to struct softirq_action
> + * @vec: pointer to first struct softirq_action in softirq_vec array
> + *
> + * The 'h' parameter, contains a pointer to the struct softirq_action
> + * which has a pointer to the action handler that is called. By subtracting
> + * the 'vec' pointer from the 'h' pointer, we can determine the softirq
> + * number. Also, when used in combination with the softirq_exit tracepoint
> + * we can determine the softirq latency.
> + */
>  TRACE_EVENT(softirq_entry,
>  
>  	TP_PROTO(struct softirq_action *h, struct softirq_action *vec),
> @@ -71,6 +98,17 @@ TRACE_EVENT(softirq_entry,
>  	TP_printk("softirq=%d action=%s", __entry->vec, __get_str(name))
>  );
>  
> +/**
> + * softirq_exit - called immediately after the softirq handler returns
> + * @h: pointer to struct softirq_action
> + * @vec: pointer to first struct softirq_action in softirq_vec array
> + *
> + * The 'h' parameter contains a pointer to the struct softirq_action
> + * that has handled the softirq. By subtracting the 'vec' pointer from
> + * the 'h' pointer, we can determine the softirq number. Also, when used in
> + * combination with the softirq_exit tracepoint we can determine the softirq
> + * latency.
> + */
>  TRACE_EVENT(softirq_exit,
>  
>  	TP_PROTO(struct softirq_action *h, struct softirq_action *vec),


-- 
~Randy
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