* [PATCH] tracing/fastboot: document the need of initcall_debug
@ 2009-06-29 7:55 Li Zefan
2009-06-29 8:21 ` Ingo Molnar
2009-06-29 8:24 ` [tip:tracing/urgent] tracing/fastboot: Document " tip-bot for Li Zefan
0 siblings, 2 replies; 7+ messages in thread
From: Li Zefan @ 2009-06-29 7:55 UTC (permalink / raw)
To: Ingo Molnar; +Cc: Frederic Weisbecker, Steven Rostedt, LKML
To use boot tracer, one should pass initcall_debug as well as
ftrace=initcall to the command line.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
kernel/trace/Kconfig | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index f7d9a4e..860c712 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -226,13 +226,13 @@ config BOOT_TRACER
the timings of the initcalls and traces key events and the identity
of tasks that can cause boot delays, such as context-switches.
- Its aim is to be parsed by the /scripts/bootgraph.pl tool to
+ Its aim is to be parsed by the scripts/bootgraph.pl tool to
produce pretty graphics about boot inefficiencies, giving a visual
representation of the delays during initcalls - but the raw
/debug/tracing/trace text output is readable too.
- You must pass in ftrace=initcall to the kernel command line
- to enable this on bootup.
+ You must pass in initcall_debug and ftrace=initcall to the kernel
+ command line to enable this on bootup.
config TRACE_BRANCH_PROFILING
bool
--
1.5.4.rc3
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] tracing/fastboot: document the need of initcall_debug
2009-06-29 7:55 [PATCH] tracing/fastboot: document the need of initcall_debug Li Zefan
@ 2009-06-29 8:21 ` Ingo Molnar
2009-06-29 9:01 ` Li Zefan
2009-06-29 8:24 ` [tip:tracing/urgent] tracing/fastboot: Document " tip-bot for Li Zefan
1 sibling, 1 reply; 7+ messages in thread
From: Ingo Molnar @ 2009-06-29 8:21 UTC (permalink / raw)
To: Li Zefan; +Cc: Frederic Weisbecker, Steven Rostedt, LKML
* Li Zefan <lizf@cn.fujitsu.com> wrote:
> To use boot tracer, one should pass initcall_debug as well as
> ftrace=initcall to the command line.
I think both should be auto-enabled if BOOT_TRACER is enabled, for
ease of use - agreed?
Ingo
^ permalink raw reply [flat|nested] 7+ messages in thread
* [tip:tracing/urgent] tracing/fastboot: Document the need of initcall_debug
2009-06-29 7:55 [PATCH] tracing/fastboot: document the need of initcall_debug Li Zefan
2009-06-29 8:21 ` Ingo Molnar
@ 2009-06-29 8:24 ` tip-bot for Li Zefan
1 sibling, 0 replies; 7+ messages in thread
From: tip-bot for Li Zefan @ 2009-06-29 8:24 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, fweisbec, rostedt, lizf, tglx, mingo
Commit-ID: 238a24f626628cb16a3015f332d649f08246ca89
Gitweb: http://git.kernel.org/tip/238a24f626628cb16a3015f332d649f08246ca89
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Mon, 29 Jun 2009 15:55:10 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 29 Jun 2009 10:22:10 +0200
tracing/fastboot: Document the need of initcall_debug
To use boot tracer, one should pass initcall_debug as well as
ftrace=initcall to the command line.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A48735E.9050002@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/trace/Kconfig | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 1551f47..019f380 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -226,13 +226,13 @@ config BOOT_TRACER
the timings of the initcalls and traces key events and the identity
of tasks that can cause boot delays, such as context-switches.
- Its aim is to be parsed by the /scripts/bootgraph.pl tool to
+ Its aim is to be parsed by the scripts/bootgraph.pl tool to
produce pretty graphics about boot inefficiencies, giving a visual
representation of the delays during initcalls - but the raw
/debug/tracing/trace text output is readable too.
- You must pass in ftrace=initcall to the kernel command line
- to enable this on bootup.
+ You must pass in initcall_debug and ftrace=initcall to the kernel
+ command line to enable this on bootup.
config TRACE_BRANCH_PROFILING
bool
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] tracing/fastboot: document the need of initcall_debug
2009-06-29 8:21 ` Ingo Molnar
@ 2009-06-29 9:01 ` Li Zefan
2009-06-29 9:14 ` Ingo Molnar
0 siblings, 1 reply; 7+ messages in thread
From: Li Zefan @ 2009-06-29 9:01 UTC (permalink / raw)
To: Ingo Molnar; +Cc: Frederic Weisbecker, Steven Rostedt, LKML
Ingo Molnar wrote:
> * Li Zefan <lizf@cn.fujitsu.com> wrote:
>
>> To use boot tracer, one should pass initcall_debug as well as
>> ftrace=initcall to the command line.
>
> I think both should be auto-enabled if BOOT_TRACER is enabled, for
> ease of use - agreed?
>
If both are auto-enabled, we'll always do boot tracing. But we want
BOOT_TRACER to be enabled and only enable boot tracing when it's needed.
But maybe we can make ftrace=initcall implies initcall_debug=1?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] tracing/fastboot: document the need of initcall_debug
2009-06-29 9:01 ` Li Zefan
@ 2009-06-29 9:14 ` Ingo Molnar
2009-06-29 11:19 ` Frederic Weisbecker
0 siblings, 1 reply; 7+ messages in thread
From: Ingo Molnar @ 2009-06-29 9:14 UTC (permalink / raw)
To: Li Zefan; +Cc: Frederic Weisbecker, Steven Rostedt, LKML
* Li Zefan <lizf@cn.fujitsu.com> wrote:
> Ingo Molnar wrote:
> > * Li Zefan <lizf@cn.fujitsu.com> wrote:
> >
> >> To use boot tracer, one should pass initcall_debug as well as
> >> ftrace=initcall to the command line.
> >
> > I think both should be auto-enabled if BOOT_TRACER is enabled, for
> > ease of use - agreed?
>
> If both are auto-enabled, we'll always do boot tracing. But we
> want BOOT_TRACER to be enabled and only enable boot tracing when
> it's needed.
>
> But maybe we can make ftrace=initcall implies initcall_debug=1?
That's reasonable indeed.
Ingo
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] tracing/fastboot: document the need of initcall_debug
2009-06-29 9:14 ` Ingo Molnar
@ 2009-06-29 11:19 ` Frederic Weisbecker
2009-06-29 19:39 ` Ingo Molnar
0 siblings, 1 reply; 7+ messages in thread
From: Frederic Weisbecker @ 2009-06-29 11:19 UTC (permalink / raw)
To: Ingo Molnar; +Cc: Li Zefan, Steven Rostedt, LKML
On Mon, Jun 29, 2009 at 11:14:22AM +0200, Ingo Molnar wrote:
>
> * Li Zefan <lizf@cn.fujitsu.com> wrote:
>
> > Ingo Molnar wrote:
> > > * Li Zefan <lizf@cn.fujitsu.com> wrote:
> > >
> > >> To use boot tracer, one should pass initcall_debug as well as
> > >> ftrace=initcall to the command line.
> > >
> > > I think both should be auto-enabled if BOOT_TRACER is enabled, for
> > > ease of use - agreed?
> >
> > If both are auto-enabled, we'll always do boot tracing. But we
> > want BOOT_TRACER to be enabled and only enable boot tracing when
> > it's needed.
> >
> > But maybe we can make ftrace=initcall implies initcall_debug=1?
>
> That's reasonable indeed.
>
> Ingo
Yeah.
Although I wonder if this tracer is still useful.
It was first written to debug fastboot, to get more
than the initcall_debug output, ie: the scheduling
events but now I guess the latter is not useful
anymore. And using initcall_debug already does the
job of printing the initcall events.
What do you think?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] tracing/fastboot: document the need of initcall_debug
2009-06-29 11:19 ` Frederic Weisbecker
@ 2009-06-29 19:39 ` Ingo Molnar
0 siblings, 0 replies; 7+ messages in thread
From: Ingo Molnar @ 2009-06-29 19:39 UTC (permalink / raw)
To: Frederic Weisbecker, Arjan van de Ven; +Cc: Li Zefan, Steven Rostedt, LKML
* Frederic Weisbecker <fweisbec@gmail.com> wrote:
> On Mon, Jun 29, 2009 at 11:14:22AM +0200, Ingo Molnar wrote:
> >
> > * Li Zefan <lizf@cn.fujitsu.com> wrote:
> >
> > > Ingo Molnar wrote:
> > > > * Li Zefan <lizf@cn.fujitsu.com> wrote:
> > > >
> > > >> To use boot tracer, one should pass initcall_debug as well as
> > > >> ftrace=initcall to the command line.
> > > >
> > > > I think both should be auto-enabled if BOOT_TRACER is enabled, for
> > > > ease of use - agreed?
> > >
> > > If both are auto-enabled, we'll always do boot tracing. But we
> > > want BOOT_TRACER to be enabled and only enable boot tracing when
> > > it's needed.
> > >
> > > But maybe we can make ftrace=initcall implies initcall_debug=1?
> >
> > That's reasonable indeed.
> >
> > Ingo
>
> Yeah.
>
> Although I wonder if this tracer is still useful. It was first
> written to debug fastboot, to get more than the initcall_debug
> output, ie: the scheduling events but now I guess the latter is
> not useful anymore. And using initcall_debug already does the job
> of printing the initcall events.
>
> What do you think?
Arjan is/was a frequent user of it. I think some neat stuff came out
of it: the trace can be fed into sysprof/ftrace and can be
visualized.
If we remove it we should first provide a replacement perfcounters
feature for it. Something like a special sw counter that 'buffers'
its events and so can be enabled during early bootup by the kernel,
and disabled once init is executed. If user-space creates a counter
on that event then it gets to read all the boot-time events in a
stream.
Or something like that. That would integrate the boot tracer
functionality into perfcounters tooling. We could do a 'perf report'
display of boot delays for example, and other neat stuff. Sounds
extremely useful and more usable than the boot tracer because this
special 'boot delays' event would always be there and can be used by
the regular 'perf' tooling to inspect bootup properties.
Ingo
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2009-06-29 19:39 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-06-29 7:55 [PATCH] tracing/fastboot: document the need of initcall_debug Li Zefan
2009-06-29 8:21 ` Ingo Molnar
2009-06-29 9:01 ` Li Zefan
2009-06-29 9:14 ` Ingo Molnar
2009-06-29 11:19 ` Frederic Weisbecker
2009-06-29 19:39 ` Ingo Molnar
2009-06-29 8:24 ` [tip:tracing/urgent] tracing/fastboot: Document " tip-bot for Li Zefan
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