Re: [PATCH] ARM: trace: Add tracepoint for the Inter Processor Interrupt

On Mon, 14 Oct 2013 15:53:27 +0200 Daniel Lezcano daniel.lezcano@linaro.org wrote:

The Inter Processor Interrupt is used on ARM to tell another processor to do a specific action. This is mainly used to emulate a timer interrupt on an idle cpu, force a cpu to reschedule or run a function on another processor context.

Add a tracepoint when raising an IPI and in the entry/exit handler function.

Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org

arch/arm/include/asm/smp.h | 9 ++++ arch/arm/kernel/smp.c | 34 ++++++++------ arch/arm64/include/asm/smp.h | 7 +++ arch/arm64/kernel/smp.c | 21 +++++++-- include/trace/events/ipi.h | 106 ++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 158 insertions(+), 19 deletions(-) create mode 100644 include/trace/events/ipi.h

diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index a8cae71c..788706c 100644 --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -18,6 +18,15 @@ # error "<asm/smp.h> included in non-SMP build" #endif +enum ipi_msg_type {

• IPI_WAKEUP,
• IPI_TIMER,
• IPI_RESCHEDULE,
• IPI_CALL_FUNC,
• IPI_CALL_FUNC_SINGLE,
• IPI_CPU_STOP,

+};

#define raw_smp_processor_id() (current_thread_info()->cpu) struct seq_file; diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 72024ea..9ca8ce8 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -46,6 +46,9 @@ #include <asm/mach/arch.h> #include <asm/mpu.h> +#define CREATE_TRACE_POINTS +#include <trace/events/ipi.h>

/*

• as from 2.5, kernels no longer have an init_tasks structure
• so we need some other way of telling a new secondary core

@@ -59,15 +62,6 @@ struct secondary_data secondary_data; */ volatile int pen_release = -1; -enum ipi_msg_type {

• IPI_WAKEUP,
• IPI_TIMER,
• IPI_RESCHEDULE,
• IPI_CALL_FUNC,
• IPI_CALL_FUNC_SINGLE,
• IPI_CPU_STOP,

-};

static DECLARE_COMPLETION(cpu_running); static struct smp_operations smp_ops; @@ -433,19 +427,25 @@ void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int)) smp_cross_call = fn; } +static void ipi_raise(const struct cpumask *mask, int ipinr) +{

• trace_ipi_raise(mask, ipinr);
• smp_cross_call(mask, ipinr);

+}

void arch_send_call_function_ipi_mask(const struct cpumask *mask) {

• smp_cross_call(mask, IPI_CALL_FUNC);

• ipi_raise(mask, IPI_CALL_FUNC);

} void arch_send_wakeup_ipi_mask(const struct cpumask *mask) {

• smp_cross_call(mask, IPI_WAKEUP);

• ipi_raise(mask, IPI_WAKEUP);

} void arch_send_call_function_single_ipi(int cpu) {

• smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);

• ipi_raise(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);

} static const char *ipi_types[NR_IPI] = { @@ -487,7 +487,7 @@ u64 smp_irq_stat_cpu(unsigned int cpu) #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST void tick_broadcast(const struct cpumask *mask) {

• smp_cross_call(mask, IPI_TIMER);

• ipi_raise(mask, IPI_TIMER);

} #endif @@ -528,6 +528,8 @@ void handle_IPI(int ipinr, struct pt_regs *regs) unsigned int cpu = smp_processor_id(); struct pt_regs *old_regs = set_irq_regs(regs);

• trace_ipi_handler_entry(ipinr);
• if (ipinr < NR_IPI) __inc_irq_stat(cpu, ipi_irqs[ipinr]);

@@ -571,11 +573,13 @@ void handle_IPI(int ipinr, struct pt_regs *regs) break; } set_irq_regs(old_regs);

• trace_ipi_handler_exit(ipinr);

} void smp_send_reschedule(int cpu) {

• smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);

• ipi_raise(cpumask_of(cpu), IPI_RESCHEDULE);

} void smp_send_stop(void) @@ -586,7 +590,7 @@ void smp_send_stop(void) cpumask_copy(&mask, cpu_online_mask); cpumask_clear_cpu(smp_processor_id(), &mask); if (!cpumask_empty(&mask))

• smp_cross_call(&mask, IPI_CPU_STOP);
  

• ipi_raise(&mask, IPI_CPU_STOP);
  

/* Wait up to one second for other CPUs to stop */ timeout = USEC_PER_SEC; diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h index 4b8023c..7ebaa3a 100644 --- a/arch/arm64/include/asm/smp.h +++ b/arch/arm64/include/asm/smp.h @@ -24,6 +24,13 @@ # error "<asm/smp.h> included in non-SMP build" #endif +enum ipi_msg_type {

• IPI_RESCHEDULE,
• IPI_CALL_FUNC,
• IPI_CALL_FUNC_SINGLE,
• IPI_CPU_STOP,

+};

#define raw_smp_processor_id() (current_thread_info()->cpu) struct seq_file; diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 78db90d..c987b9f 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -48,6 +48,9 @@ #include <asm/tlbflush.h> #include <asm/ptrace.h> +#define CREATE_TRACE_POINTS +#include <trace/events/ipi.h>

/*

• as from 2.5, kernels no longer have an init_tasks structure
• so we need some other way of telling a new secondary core

@@ -426,14 +429,20 @@ void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int)) smp_cross_call = fn; } +static void ipi_raise(const struct cpumask *mask, int ipinr) +{

• trace_ipi_raise(mask, ipinr);
• smp_cross_call(mask, ipinr);

+}

void arch_send_call_function_ipi_mask(const struct cpumask *mask) {

• smp_cross_call(mask, IPI_CALL_FUNC);

• ipi_raise(mask, IPI_CALL_FUNC);

} void arch_send_call_function_single_ipi(int cpu) {

• smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);

• ipi_raise(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);

} static const char *ipi_types[NR_IPI] = { @@ -501,6 +510,8 @@ void handle_IPI(int ipinr, struct pt_regs *regs) unsigned int cpu = smp_processor_id(); struct pt_regs *old_regs = set_irq_regs(regs);

• trace_ipi_handler_entry(ipinr);
• if (ipinr >= IPI_RESCHEDULE && ipinr < IPI_RESCHEDULE + NR_IPI) __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_RESCHEDULE]);

@@ -532,11 +543,13 @@ void handle_IPI(int ipinr, struct pt_regs *regs) break; } set_irq_regs(old_regs);

• trace_ipi_handler_exit(ipinr);

} void smp_send_reschedule(int cpu) {

• smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);

• ipi_raise(cpumask_of(cpu), IPI_RESCHEDULE);

} void smp_send_stop(void) @@ -549,7 +562,7 @@ void smp_send_stop(void) cpumask_copy(&mask, cpu_online_mask); cpu_clear(smp_processor_id(), mask);

• smp_cross_call(&mask, IPI_CPU_STOP);
  

• ipi_raise(&mask, IPI_CPU_STOP);
  

  }

/* Wait up to one second for other CPUs to stop */ diff --git a/include/trace/events/ipi.h b/include/trace/events/ipi.h new file mode 100644 index 0000000..4d6648a --- /dev/null +++ b/include/trace/events/ipi.h @@ -0,0 +1,106 @@ +#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>

+struct cpumask;

+#define ipi_name(ipinr) { IPI_##ipinr, #ipinr } +#define show_ipi_name(val) \

• __print_symbolic(val, \

• 	 ipi_name(WAKEUP),		\
  

• 	 ipi_name(TIMER),		\
  

• 	 ipi_name(RESCHEDULE),		\
  

• 	 ipi_name(CALL_FUNC),		\
  

• 	 ipi_name(CALL_FUNC_SINGLE),	\
  

• 	 ipi_name(CPU_STOP))
  

+/**

• • ipi_handle_entry - called right before the IPI handler
• • @ipinr: the IPI number
• • The @ipinr value must be valid and the action name associated with
• • the IPI value is given in the trace.
• */

+TRACE_EVENT_CONDITION(ipi_handler_entry,

• TP_PROTO(int ipinr),
• TP_ARGS(ipinr),
• TP_CONDITION(ipinr < NR_IPI && ipinr >= 0),
• TP_STRUCT__entry(

•    __field(unsigned int, ipinr)
  

• ),
• TP_fast_assign(

•    __entry->ipinr = ipinr;
  

• ),
• TP_printk("ipi=%d, name=%s", __entry->ipinr,

•      show_ipi_name(__entry->ipinr))
  

+);

+/**

• • ipi_handle_exit - called right after the IPI handler
• • @ipinr: the IPI number
• • The @ipinr value must be valid and the action name associated with
• • the IPI value is given in the trace.
• */

+TRACE_EVENT_CONDITION(ipi_handler_exit,

• TP_PROTO(int ipinr),
• TP_ARGS(ipinr),
• TP_CONDITION(ipinr < NR_IPI && ipinr >= 0),
• TP_STRUCT__entry(

•    __field(int, ipinr)
  

Here you have "int" and above for the "*_entry" you have unsigned int. Is there a difference?

If not, you should combine these two into a DECLARE_EVENT_CLASS() and then use DEFINE_EVENT_CONDITION() for the two tracepoints.

• ),
• TP_fast_assign(

•    __entry->ipinr = ipinr;
  

• ),
• TP_printk("ipi=%d, name=%s", __entry->ipinr,

•      show_ipi_name(__entry->ipinr))
  

+);

+/**

• • ipi_raise - called when a smp cross call is made
• • @ipinr: the IPI number
• • @cpumask: the recipients for the IPI
• • The @ipinr value must be valid and the action name associated with
• • the IPI value is given in the trace.
• */

+TRACE_EVENT_CONDITION(ipi_raise,

• TP_PROTO(const struct cpumask *cpumask, int ipinr),
• TP_ARGS(cpumask, ipinr),

Why pass in the cpumask if it isn't used? Do you expect to hook something else to the tracepoint?

-- Steve

• TP_CONDITION(ipinr < NR_IPI && ipinr >= 0),
• TP_STRUCT__entry(

•    __field(int, ipinr)
  

• ),
• TP_fast_assign(

•    __entry->ipinr = ipinr;
  

• ),
• TP_printk("ipi=%d, name=%s", __entry->ipinr,

•      show_ipi_name(__entry->ipinr))
  

+);

+#endif /* _TRACE_IPI_H */

+/* This part must be outside protection */ +#include <trace/define_trace.h>