Subject: Re: [RFC PATCH v2 1/5] irq: add tracepoint to softirq_raise

From: Koki Sanagi <[email-masked]>
Date: Fri, 25 Jun 2010 09:49:47 +0900

Hi Steven,

Sorry, I submitted other patches to only netdev.
I'll resubmit soon all patches to linux-kernel.

(2010/06/25 4:15), Steven Rostedt wrote:
> Hi Koki,
> 
> Your subject says 1/5 but I do not see any other patches.
> 
> 
> On Thu, 2010-06-24 at 17:16 +0900, Koki Sanagi wrote:
>> This patch adds a tracepoint to raising of softirq.
>> This is useful if you want to detect which hard interrupt raise softirq
>> and lets you know a time between raising softirq and performing softirq.
>> Combinating with other tracepoint, it lets us know a process of packets
>> (See patch 0/5).
>>
>>           <idle>-0     [001] 241229.957184: softirq_raise: vec=3 [action=NET_RX]
>>           <idle>-0     [000] 241229.993399: softirq_raise: vec=1 [action=TIMER]
>>           <idle>-0     [000] 241229.993400: softirq_raise: vec=9 [action=RCU]
>>
>> This is a same patch Lai Jiangshan submitted.
>> http://marc.info/?l=linux-kernel&m=126026122728732&w=2
>>
>> Signed-off-by: Koki Sanagi <[email-masked]>
>> ---
>>  include/linux/interrupt.h  |    8 +++++++-
>>  include/trace/events/irq.h |   34 +++++++++++++++++++++++++++++++---
>>  2 files changed, 38 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
>> index c233113..1cb5726 100644
>> --- a/include/linux/interrupt.h
>> +++ b/include/linux/interrupt.h
>> @@ -18,6 +18,7 @@
>>  #include <asm/atomic.h>
>>  #include <asm/ptrace.h>
>>  #include <asm/system.h>
>> +#include <trace/events/irq.h>
>>  
>>  /*
>>   * These correspond to the IORESOURCE_IRQ_* defines in
>> @@ -402,7 +403,12 @@ asmlinkage void do_softirq(void);
>>  asmlinkage void __do_softirq(void);
>>  extern void open_softirq(int nr, void (*action)(struct softirq_action *));
>>  extern void softirq_init(void);
>> -#define __raise_softirq_irqoff(nr) do { or_softirq_pending(1UL << (nr)); } while (0)
>> +static inline void __raise_softirq_irqoff(unsigned int nr)
>> +{
>> +	trace_softirq_raise(nr);
>> +	or_softirq_pending(1UL << nr);
>> +}
>> +
>>  extern void raise_softirq_irqoff(unsigned int nr);
>>  extern void raise_softirq(unsigned int nr);
>>  extern void wakeup_softirqd(void);
>> diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
>> index 0e4cfb6..7cb7435 100644
>> --- a/include/trace/events/irq.h
>> +++ b/include/trace/events/irq.h
>> @@ -5,7 +5,9 @@
>>  #define _TRACE_IRQ_H
>>  
>>  #include <linux/tracepoint.h>
>> -#include <linux/interrupt.h>
>> +
>> +struct irqaction;
>> +struct softirq_action;
>>  
>>  #define softirq_name(sirq) { sirq##_SOFTIRQ, #sirq }
>>  #define show_softirq_name(val)				\
>> @@ -82,6 +84,32 @@ TRACE_EVENT(irq_handler_exit,
>>  		  __entry->irq, __entry->ret ? "handled" : "unhandled")
>>  );
>>  
>> +/**
>> + * softirq_raise - called immediately when a softirq is raised
>> + * @nr: softirq vector number
>> + *
>> + * Tracepoint for tracing when softirq action is raised.
>> + * Also, when used in combination with the softirq_entry tracepoint
>> + * we can determine the softirq raise latency.
>> + */
>> +TRACE_EVENT(softirq_raise,
>> +
>> +	TP_PROTO(unsigned int nr),
>> +
>> +	TP_ARGS(nr),
>> +
>> +	TP_STRUCT__entry(
>> +		__field(	unsigned int,	vec	)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->vec	= nr;
>> +	),
>> +
>> +	TP_printk("vec=%d [action=%s]", __entry->vec,
>> +		show_softirq_name(__entry->vec))
> 
> Hmm, is there a way to reuse a DECLARE_EVENT_CLASS here?
> 
>> +);
>> +
>>  DECLARE_EVENT_CLASS(softirq,
>>  
>>  	TP_PROTO(struct softirq_action *h, struct softirq_action *vec),
>> @@ -89,11 +117,11 @@ DECLARE_EVENT_CLASS(softirq,
>>  	TP_ARGS(h, vec),
>>  
>>  	TP_STRUCT__entry(
>> -		__field(	int,	vec			)
>> +		__field(	unsigned int,	vec	)
>>  	),
>>  
>>  	TP_fast_assign(
>> -		__entry->vec = (int)(h - vec);
>> +		__entry->vec = (unsigned int)(h - vec);
> 
> Just curious, did you see the original as a bug?
> 
> -- Steve
> 
>>  	),
>>  
>>  	TP_printk("vec=%d [action=%s]", __entry->vec,
> 
> 
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