* Re: systemtap broken by removal of register_timer_hook
2013-04-03 14:44 ` Frank Ch. Eigler
@ 2013-04-03 18:38 ` Josh Stone
2013-04-04 12:46 ` Frederic Weisbecker
2013-04-10 11:25 ` Ingo Molnar
2 siblings, 0 replies; 12+ messages in thread
From: Josh Stone @ 2013-04-03 18:38 UTC (permalink / raw)
To: Frank Ch. Eigler
Cc: Frederic Weisbecker, Mel Gorman, Ingo Molnar, LKML, SystemTap
On 04/03/2013 07:44 AM, Frank Ch. Eigler wrote:
> Hi -
>
> On Wed, Apr 03, 2013 at 02:49:53PM +0200, Frederic Weisbecker wrote:
>
>> Sounds good, would you like to propose a version? We are also
>> interested in a timer tick event tracepoint for dynticks debugging.
>
> How about this?
>
> Author: Frank Ch. Eigler <fche@redhat.com>
> Date: Wed Apr 3 10:35:21 2013 -0400
>
> profiling: add profile_tick tracepoint
>
> Commit ba6fdda4 removed the timer_hook mechanism for modules to listen
> to profiling timer ticks (without having to set up more complicated
> perf mechanisms). To reduce the impact on out-of-tree users, a
> TRACE_EVENT-flavoured tracepoint is added in its place. Tested with
> perf and systemtap.
One nice benefit over register_timer_hook() is that a tracepoint allows
multiple consumers, like the old register_profile_notifier() did.
>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Mel Gorman <mgorman@suse.de>
> Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
>
> diff --git a/include/trace/events/profile.h b/include/trace/events/profile.h
> new file mode 100644
> index 0000000..b48b6fe
> --- /dev/null
> +++ b/include/trace/events/profile.h
> @@ -0,0 +1,35 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM profile
> +
> +#if !defined(_TRACE_PROFILE_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_PROFILE_H
> +
> +#include <linux/tracepoint.h>
> +
> +
> +struct pt_regs;
> +
> +/**
> + * profile_tick - called when the profiling timer ticks
> + * @regs: pointer to struct pt_regs*
> + */
> +
> +TRACE_EVENT(profile_tick,
> + TP_PROTO(int type, struct pt_regs *regs),
> + TP_ARGS(type, regs),
> + TP_STRUCT__entry(
> + __field( int, type )
> + __field( struct pt_regs*, regs )
> + ),
> + TP_fast_assign(
> + __entry->type = type;
> + __entry->regs = regs;
> + ),
> + TP_printk("type=%d regs=%p", __entry->type, __entry->regs)
> +);
I agree that full regs are good for the tracepoint in general, but I
doubt that this pointer is useful for the printk. Maybe instead print
instruction_pointer(__entry->regs)?
> +
> +
> +#endif /* _TRACE_PROFILE_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/kernel/profile.c b/kernel/profile.c
> index dc3384e..d61f921 100644
> --- a/kernel/profile.c
> +++ b/kernel/profile.c
> @@ -29,6 +29,9 @@
> #include <asm/irq_regs.h>
> #include <asm/ptrace.h>
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/profile.h>
> +
> struct profile_hit {
> u32 pc, hits;
> };
> @@ -414,6 +417,8 @@ void profile_tick(int type)
> {
> struct pt_regs *regs = get_irq_regs();
>
> + trace_profile_tick(type, regs);
> +
> if (!user_mode(regs) && prof_cpu_mask != NULL &&
> cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
> profile_hit(type, (void *)profile_pc(regs));
>
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: systemtap broken by removal of register_timer_hook
2013-04-03 14:44 ` Frank Ch. Eigler
2013-04-03 18:38 ` Josh Stone
@ 2013-04-04 12:46 ` Frederic Weisbecker
2013-04-19 14:47 ` Frank Ch. Eigler
2013-04-10 11:25 ` Ingo Molnar
2 siblings, 1 reply; 12+ messages in thread
From: Frederic Weisbecker @ 2013-04-04 12:46 UTC (permalink / raw)
To: Frank Ch. Eigler; +Cc: Mel Gorman, Ingo Molnar, LKML, SystemTap
2013/4/3 Frank Ch. Eigler <fche@redhat.com>:
> Hi -
>
> On Wed, Apr 03, 2013 at 02:49:53PM +0200, Frederic Weisbecker wrote:
>
>> Sounds good, would you like to propose a version? We are also
>> interested in a timer tick event tracepoint for dynticks debugging.
>
> How about this?
>
> Author: Frank Ch. Eigler <fche@redhat.com>
> Date: Wed Apr 3 10:35:21 2013 -0400
>
> profiling: add profile_tick tracepoint
>
> Commit ba6fdda4 removed the timer_hook mechanism for modules to listen
> to profiling timer ticks (without having to set up more complicated
> perf mechanisms). To reduce the impact on out-of-tree users, a
> TRACE_EVENT-flavoured tracepoint is added in its place. Tested with
> perf and systemtap.
>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Mel Gorman <mgorman@suse.de>
> Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
>
> diff --git a/include/trace/events/profile.h b/include/trace/events/profile.h
> new file mode 100644
> index 0000000..b48b6fe
> --- /dev/null
> +++ b/include/trace/events/profile.h
> @@ -0,0 +1,35 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM profile
> +
> +#if !defined(_TRACE_PROFILE_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_PROFILE_H
> +
> +#include <linux/tracepoint.h>
> +
> +
> +struct pt_regs;
> +
> +/**
> + * profile_tick - called when the profiling timer ticks
> + * @regs: pointer to struct pt_regs*
> + */
> +
> +TRACE_EVENT(profile_tick,
> + TP_PROTO(int type, struct pt_regs *regs),
> + TP_ARGS(type, regs),
> + TP_STRUCT__entry(
> + __field( int, type )
> + __field( struct pt_regs*, regs )
> + ),
> + TP_fast_assign(
> + __entry->type = type;
> + __entry->regs = regs;
> + ),
> + TP_printk("type=%d regs=%p", __entry->type, __entry->regs)
> +);
> +
> +
> +#endif /* _TRACE_PROFILE_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/kernel/profile.c b/kernel/profile.c
> index dc3384e..d61f921 100644
> --- a/kernel/profile.c
> +++ b/kernel/profile.c
> @@ -29,6 +29,9 @@
> #include <asm/irq_regs.h>
> #include <asm/ptrace.h>
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/profile.h>
> +
> struct profile_hit {
> u32 pc, hits;
> };
> @@ -414,6 +417,8 @@ void profile_tick(int type)
> {
> struct pt_regs *regs = get_irq_regs();
>
> + trace_profile_tick(type, regs);
> +
It would be better not to tie this to CONFIG_PROFILING.
A tracepoint in update_process_times() instead would be great but it's
sometimes called several times in a tick from some archs.
Probably we need something like:
static inline tick_trace(struct pt_regs *regs)
{
trace_timer_tick(regs);
profile_tick(CPU_PROFILING);
}
Then replace all calls to profile_tick() with the above.
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: systemtap broken by removal of register_timer_hook
2013-04-04 12:46 ` Frederic Weisbecker
@ 2013-04-19 14:47 ` Frank Ch. Eigler
2013-04-30 0:19 ` Frederic Weisbecker
0 siblings, 1 reply; 12+ messages in thread
From: Frank Ch. Eigler @ 2013-04-19 14:47 UTC (permalink / raw)
To: Frederic Weisbecker; +Cc: Mel Gorman, Ingo Molnar, LKML, SystemTap
Hi, Frederic -
> > How about this?
> >
> > Author: Frank Ch. Eigler <fche@redhat.com>
> > Date: Wed Apr 3 10:35:21 2013 -0400
> >
> > profiling: add profile_tick tracepoint
> > [...]
> It would be better not to tie this to CONFIG_PROFILING.
> A tracepoint in update_process_times() instead would be great but it's
> sometimes called several times in a tick from some archs.
> Probably we need something like:
>
> static inline tick_trace(struct pt_regs *regs)
> {
> trace_timer_tick(regs);
> profile_tick(CPU_PROFILING);
> }
I looked into this, but found no natural place to define such an
inline function from which to call into a tracepoint, without having
to #include the <event/FOO.h> file many times. Nor does it seem
appropriate to do the identical #define CREATE_TRACE_POINTS part from
all the different arch/.../*.c files that may call into that inline.
If you'd like to stick to this idea, please advise further where you
think the tracepoint definition & declarations should go.
In the alternative, here is v2 of the patch, just changing the
tracepoint-printing argument as suggested by jistone.
- FChE
---------------
Author: Frank Ch. Eigler <fche@redhat.com>
Date: Wed Apr 3 10:35:21 2013 -0400
profiling: add profile_tick tracepoint
Commit ba6fdda4 removed the timer_hook mechanism for modules to listen
to profiling timer ticks (without having to set up more complicated
perf mechanisms). To reduce the impact on out-of-tree users such as
systemtap, a TRACE_EVENT-flavoured tracepoint is added in its place.
Tested with perf and systemtap.
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
diff --git a/include/trace/events/profile.h b/include/trace/events/profile.h
new file mode 100644
index 0000000..445aee7
--- /dev/null
+++ b/include/trace/events/profile.h
@@ -0,0 +1,37 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM profile
+
+#if !defined(_TRACE_PROFILE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_PROFILE_H
+
+#include <linux/tracepoint.h>
+
+
+struct pt_regs;
+
+/**
+ * profile_tick - called when the profiling timer ticks
+ * @type: profiling tick type, generally @CPU_PROFILING
+ * @regs: pointer to struct pt_regs*
+ */
+
+TRACE_EVENT(profile_tick,
+ TP_PROTO(int type, struct pt_regs *regs),
+ TP_ARGS(type, regs),
+ TP_STRUCT__entry(
+ __field( int, type )
+ __field( struct pt_regs*, regs )
+ ),
+ TP_fast_assign(
+ __entry->type = type;
+ __entry->regs = regs;
+ ),
+ TP_printk("type=%d ip=%p", __entry->type,
+ instruction_pointer(__entry->regs))
+);
+
+
+#endif /* _TRACE_PROFILE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/kernel/profile.c b/kernel/profile.c
index dc3384e..d61f921 100644
--- a/kernel/profile.c
+++ b/kernel/profile.c
@@ -29,6 +29,9 @@
#include <asm/irq_regs.h>
#include <asm/ptrace.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/profile.h>
+
struct profile_hit {
u32 pc, hits;
};
@@ -414,6 +417,8 @@ void profile_tick(int type)
{
struct pt_regs *regs = get_irq_regs();
+ trace_profile_tick(type, regs);
+
if (!user_mode(regs) && prof_cpu_mask != NULL &&
cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
profile_hit(type, (void *)profile_pc(regs));
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: systemtap broken by removal of register_timer_hook
2013-04-19 14:47 ` Frank Ch. Eigler
@ 2013-04-30 0:19 ` Frederic Weisbecker
2013-04-30 17:27 ` Frank Ch. Eigler
0 siblings, 1 reply; 12+ messages in thread
From: Frederic Weisbecker @ 2013-04-30 0:19 UTC (permalink / raw)
To: Frank Ch. Eigler
Cc: Mel Gorman, Ingo Molnar, LKML, SystemTap, Thomas Gleixner
On Fri, Apr 19, 2013 at 10:46:55AM -0400, Frank Ch. Eigler wrote:
> Hi, Frederic -
>
>
> > > How about this?
> > >
> > > Author: Frank Ch. Eigler <fche@redhat.com>
> > > Date: Wed Apr 3 10:35:21 2013 -0400
> > >
> > > profiling: add profile_tick tracepoint
> > > [...]
>
> > It would be better not to tie this to CONFIG_PROFILING.
> > A tracepoint in update_process_times() instead would be great but it's
> > sometimes called several times in a tick from some archs.
> > Probably we need something like:
> >
> > static inline tick_trace(struct pt_regs *regs)
> > {
> > trace_timer_tick(regs);
> > profile_tick(CPU_PROFILING);
> > }
>
> I looked into this, but found no natural place to define such an
> inline function from which to call into a tracepoint, without having
> to #include the <event/FOO.h> file many times.
You could include it from linux/profile.h or linux/tick.h and
define profile_tick to "{ trace_tick(); __profile_tick()}" .
But in a second thought, using a tracepoint in a general purpose header
resulted in bad circular headers dependency in the past, we had bitter
experiences with trace_softirq_raise for example.
> Nor does it seem
> appropriate to do the identical #define CREATE_TRACE_POINTSw part from
> all the different arch/.../*.c files that may call into that inline.
>
> If you'd like to stick to this idea, please advise further where you
> think the tracepoint definition & declarations should go.
>
> In the alternative, here is v2 of the patch, just changing the
> tracepoint-printing argument as suggested by jistone.
But your tracepoint still depends on CONFIG_PROFILING and I would
really like to avoid that.
How about creating trace_tick() in include/trace/events/timer.h
and call it from tick_periodic() and tick_sched_handle().
This only leaves the archs that don't support generic clockevents
behind. This should be no big deal, they can integrate this tracepoint
later if they need to.
Thanks.
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: systemtap broken by removal of register_timer_hook
2013-04-30 0:19 ` Frederic Weisbecker
@ 2013-04-30 17:27 ` Frank Ch. Eigler
2013-05-06 23:12 ` Frederic Weisbecker
0 siblings, 1 reply; 12+ messages in thread
From: Frank Ch. Eigler @ 2013-04-30 17:27 UTC (permalink / raw)
To: Frederic Weisbecker
Cc: Mel Gorman, Ingo Molnar, LKML, SystemTap, Thomas Gleixner
Hi -
> [...] How about creating trace_tick() in
> include/trace/events/timer.h and call it from tick_periodic() and
> tick_sched_handle(). [...]
Like this?
From facee64445c0dcc717e99c474c5c7dcdd31b9a74 Mon Sep 17 00:00:00 2001
From: "Frank Ch. Eigler" <fche@redhat.com>
Date: Wed, 3 Apr 2013 10:35:21 -0400
Subject: [PATCH] profiling: add tick tracepoint
Commit ba6fdda4 removed the timer_hook mechanism for modules to listen
to profiling timer ticks (without having to set up more complicated
perf mechanisms). To reduce the impact on out-of-tree users such as
systemtap, a TRACE_EVENT-flavoured tracepoint is added in its place,
invoked right beside profile_tick() in kernel/time/tick-*.c.
Tested with perf and systemtap.
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
---
include/trace/events/timer.h | 20 ++++++++++++++++++++
kernel/time/tick-common.c | 2 ++
kernel/time/tick-sched.c | 2 ++
3 files changed, 24 insertions(+)
diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index 425bcfe..ec4c2d0 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -323,6 +323,26 @@ TRACE_EVENT(itimer_expire,
(int) __entry->pid, (unsigned long long)__entry->now)
);
+
+struct pt_regs;
+
+/**
+ * tick - called when the profiling timer ticks
+ * @regs: pointer to struct pt_regs*
+ */
+TRACE_EVENT(tick,
+ TP_PROTO(struct pt_regs *regs),
+ TP_ARGS(regs),
+ TP_STRUCT__entry(
+ __field( struct pt_regs*, regs )
+ ),
+ TP_fast_assign(
+ __entry->regs = regs;
+ ),
+ TP_printk("ip=%p", (void *) instruction_pointer(__entry->regs))
+);
+
+
#endif /* _TRACE_TIMER_H */
/* This part must be outside protection */
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index b1600a6..5f4227f 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -18,6 +18,7 @@
#include <linux/percpu.h>
#include <linux/profile.h>
#include <linux/sched.h>
+#include <trace/events/timer.h>
#include <asm/irq_regs.h>
@@ -74,6 +75,7 @@ static void tick_periodic(int cpu)
update_process_times(user_mode(get_irq_regs()));
profile_tick(CPU_PROFILING);
+ trace_tick(get_irq_regs());
}
/*
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index a19a399..447be56 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -21,6 +21,7 @@
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/irq_work.h>
+#include <trace/events/timer.h>
#include <asm/irq_regs.h>
@@ -140,6 +141,7 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs)
#endif
update_process_times(user_mode(regs));
profile_tick(CPU_PROFILING);
+ trace_tick(get_irq_regs());
}
/*
--
1.8.2
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: systemtap broken by removal of register_timer_hook
2013-04-30 17:27 ` Frank Ch. Eigler
@ 2013-05-06 23:12 ` Frederic Weisbecker
0 siblings, 0 replies; 12+ messages in thread
From: Frederic Weisbecker @ 2013-05-06 23:12 UTC (permalink / raw)
To: Frank Ch. Eigler
Cc: Mel Gorman, Ingo Molnar, LKML, SystemTap, Thomas Gleixner
On Tue, Apr 30, 2013 at 01:27:20PM -0400, Frank Ch. Eigler wrote:
> Hi -
>
> > [...] How about creating trace_tick() in
> > include/trace/events/timer.h and call it from tick_periodic() and
> > tick_sched_handle(). [...]
>
> Like this?
>
>
> From facee64445c0dcc717e99c474c5c7dcdd31b9a74 Mon Sep 17 00:00:00 2001
> From: "Frank Ch. Eigler" <fche@redhat.com>
> Date: Wed, 3 Apr 2013 10:35:21 -0400
> Subject: [PATCH] profiling: add tick tracepoint
I'd rather entitle "timer: Add tick tracepoint", as it doesn't depend
on the profiling stuff.
>
> Commit ba6fdda4 removed the timer_hook mechanism for modules to listen
> to profiling timer ticks (without having to set up more complicated
> perf mechanisms). To reduce the impact on out-of-tree users such as
> systemtap, a TRACE_EVENT-flavoured tracepoint is added in its place,
> invoked right beside profile_tick() in kernel/time/tick-*.c.
> Tested with perf and systemtap.
>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Mel Gorman <mgorman@suse.de>
> Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
> ---
> include/trace/events/timer.h | 20 ++++++++++++++++++++
> kernel/time/tick-common.c | 2 ++
> kernel/time/tick-sched.c | 2 ++
> 3 files changed, 24 insertions(+)
>
> diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
> index 425bcfe..ec4c2d0 100644
> --- a/include/trace/events/timer.h
> +++ b/include/trace/events/timer.h
> @@ -323,6 +323,26 @@ TRACE_EVENT(itimer_expire,
> (int) __entry->pid, (unsigned long long)__entry->now)
> );
>
> +
> +struct pt_regs;
> +
> +/**
> + * tick - called when the profiling timer ticks
> + * @regs: pointer to struct pt_regs*
> + */
> +TRACE_EVENT(tick,
> + TP_PROTO(struct pt_regs *regs),
> + TP_ARGS(regs),
> + TP_STRUCT__entry(
> + __field( struct pt_regs*, regs )
I doubt the pointer to the regs is interesting in userland.
How about "void *ip" instead?
> + ),
> + TP_fast_assign(
> + __entry->regs = regs;
> + ),
> + TP_printk("ip=%p", (void *) instruction_pointer(__entry->regs))
> +);
> +
> +
> #endif /* _TRACE_TIMER_H */
>
> /* This part must be outside protection */
> diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
> index b1600a6..5f4227f 100644
> --- a/kernel/time/tick-common.c
> +++ b/kernel/time/tick-common.c
> @@ -18,6 +18,7 @@
> #include <linux/percpu.h>
> #include <linux/profile.h>
> #include <linux/sched.h>
> +#include <trace/events/timer.h>
>
> #include <asm/irq_regs.h>
>
> @@ -74,6 +75,7 @@ static void tick_periodic(int cpu)
>
> update_process_times(user_mode(get_irq_regs()));
> profile_tick(CPU_PROFILING);
> + trace_tick(get_irq_regs());
I suggest storing get_irq_regs() in a local variable so the function
doesn't fetch it twice from whatever per cpu area.
> }
>
> /*
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index a19a399..447be56 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -21,6 +21,7 @@
> #include <linux/sched.h>
> #include <linux/module.h>
> #include <linux/irq_work.h>
> +#include <trace/events/timer.h>
>
> #include <asm/irq_regs.h>
>
> @@ -140,6 +141,7 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs)
> #endif
> update_process_times(user_mode(regs));
> profile_tick(CPU_PROFILING);
> + trace_tick(get_irq_regs());
And here you can reuse the regs parameter.
> }
>
> /*
> --
> 1.8.2
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: systemtap broken by removal of register_timer_hook
2013-04-03 14:44 ` Frank Ch. Eigler
2013-04-03 18:38 ` Josh Stone
2013-04-04 12:46 ` Frederic Weisbecker
@ 2013-04-10 11:25 ` Ingo Molnar
2 siblings, 0 replies; 12+ messages in thread
From: Ingo Molnar @ 2013-04-10 11:25 UTC (permalink / raw)
To: Frank Ch. Eigler; +Cc: Frederic Weisbecker, Mel Gorman, LKML, SystemTap
* Frank Ch. Eigler <fche@redhat.com> wrote:
> Hi -
>
> On Wed, Apr 03, 2013 at 02:49:53PM +0200, Frederic Weisbecker wrote:
>
> > Sounds good, would you like to propose a version? We are also
> > interested in a timer tick event tracepoint for dynticks debugging.
>
> How about this?
>
> Author: Frank Ch. Eigler <fche@redhat.com>
> Date: Wed Apr 3 10:35:21 2013 -0400
>
> profiling: add profile_tick tracepoint
>
> Commit ba6fdda4 removed the timer_hook mechanism for modules to listen
> to profiling timer ticks (without having to set up more complicated
> perf mechanisms). To reduce the impact on out-of-tree users, a
> TRACE_EVENT-flavoured tracepoint is added in its place. Tested with
> perf and systemtap.
I'd suggest mentioning SystemTap here as the driving motivation. SystemTap
triggered a generic kernel improvement here, no need to hide its identity!
Thanks,
Ingo
^ permalink raw reply [flat|nested] 12+ messages in thread