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Message-ID: <20131014232004.5cbedbb8@gandalf.local.home>
Date: Mon, 14 Oct 2013 23:20:04 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: fweisbec@...il.com, mingo@...hat.com, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, patches@...aro.org,
linaro-kernel@...ts.linaro.org, shaojie.sun@...aro.org
Subject: Re: [PATCH] ARM: trace: Add tracepoint for the Inter Processor
Interrupt
On Mon, 14 Oct 2013 15:53:27 +0200
Daniel Lezcano <daniel.lezcano@...aro.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@...aro.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>
--
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