Date:	Mon, 21 Jan 2013 22:12:46 +0000
From:	Seiji Aguchi <seiji.aguchi@....com>
To:	"x86@...nel.org" <x86@...nel.org>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>,
	"H. Peter Anvin (hpa@...or.com)" <hpa@...or.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Thomas Gleixner (tglx@...utronix.de)" <tglx@...utronix.de>,
	"'mingo@...e.hu' (mingo@...e.hu)" <mingo@...e.hu>,
	"Borislav Petkov (bp@...en8.de)" <bp@...en8.de>,
	Satoru Moriya <satoru.moriya@....com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>
Subject: [RFC][PATCH v8 0/3]trace,x86: irq vector tracepoint support

Change log 

 v7 -> v8
 - Rebase to 3.8-rc4
 - Add a patch 1/3 introducing DEFINE_EVENT_FN() macro.
 - Rename original patches 1/2 and 2/2 to 2/3 and 3/3.
 - Change a definition of tracepoint to use DEFINE_EVENT_FN(). (patch 2/3)
 - Change alloc_intr_gate() to use do{}while(0) to avoid a warning 
   of checkpatch.pl. (patch 2/3)
 - Move entering_irq()/exiting_irq() to arch/x86/include/asm/apic.h (patch 3/3)

 v6 -> v7
 - Divide into two patches to make a code review easier.
   Summery of each patch is as follows.
    - Patch 1/2
      - Add an irq_vector tracing infrastructure.
      - Create idt_table for tracing. It is refactored to avoid duplicating
        existing logic.
      - Duplicate new irq handlers inserted tracepoints.

    - Patch 2/2
      - Share a common logic among irq handlers to make them
        manageable and readable.

 v5 -> v6
 - Rebased to 3.7

 v4 -> v5
 - Rebased to 3.6.0

 - Introduce a logic switching IDT at enabling/disabling TP time 
   so that a time penalty makes a zero when tracepoints are disabled.
   This IDT is created only when CONFIG_TRACEPOINTS is enabled.

 - Remove arch_irq_vector_entry/exit and add followings again
   so that we can add each tracepoint in a generic way.
   - error_apic_vector
   - thermal_apic_vector
   - threshold_apic_vector
   - spurious_apic_vector
   - x86_platform_ipi_vector

 - Drop nmi tracepoints to begin with apic interrupts and discuss a logic switching
   IDT first.

 - Move irq_vectors.h in the directory of arch/x86/include/asm/trace because
   I'm not sure if a logic switching IDT is sharable with other architectures.

 v3 -> v4
 - Add a latency measurement of each tracepoint
 - Rebased to 3.6-rc6

 v2 -> v3
 - Remove an invalidate_tlb_vector event because it was replaced by a call function vector
   in a following commit.
   http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=52aec3308db85f4e9f5c8b9f5dc4fbd0138c6fa4

 v1 -> v2
 - Modify variable name from irq to vector.
 - Merge arch-specific tracepoints below to an arch_irq_vector_entry/exit.
   - error_apic_vector
   - thermal_apic_vector
   - threshold_apic_vector
   - spurious_apic_vector
   - x86_platform_ipi_vector

[Purpose of this patch]

As Vaibhav explained in the thread below, tracepoints for irq vectors
are useful.

http://www.spinics.net/lists/mm-commits/msg85707.html

<snip>
The current interrupt traces from irq_handler_entry and irq_handler_exit
provide when an interrupt is handled.  They provide good data about when
the system has switched to kernel space and how it affects the currently
running processes.

There are some IRQ vectors which trigger the system into kernel space,
which are not handled in generic IRQ handlers.  Tracing such events gives
us the information about IRQ interaction with other system events.

The trace also tells where the system is spending its time.  We want to
know which cores are handling interrupts and how they are affecting other
processes in the system.  Also, the trace provides information about when
the cores are idle and which interrupts are changing that state.
<snip>

On the other hand, my usecase is tracing just local timer event and 
getting a value of instruction pointer.

I suggested to add an argument local timer event to get instruction pointer before.
But there is another way to get it with external module like systemtap.
So, I don't need to add any argument to irq vector tracepoints now.

[Patch Description]

Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events.
But there is an above use case to trace specific irq_vector rather than tracing all events.
In this case, we are concerned about overhead due to unwanted events.

This patch adds following tracepoints instead of introducing irq_vector_entry/exit.
so that we can enable them independently.
   - local_timer_vector
   - reschedule_vector
   - call_function_vector
   - call_function_single_vector 
   - irq_work_entry_vector
   - error_apic_vector
   - thermal_apic_vector
   - threshold_apic_vector
   - spurious_apic_vector
   - x86_platform_ipi_vector

Please see descriptions in each patch.

Seiji Aguchi (3):
  tracing: Add DEFINE_EVENT_FN() macro
  trace,x86: add x86 irq vector tracepoints
  trace,x86: code-sharing between non-trace and trace irq handlers

 arch/x86/include/asm/apic.h              |   27 +++++
 arch/x86/include/asm/desc.h              |   33 ++++++-
 arch/x86/include/asm/entry_arch.h        |    5 +-
 arch/x86/include/asm/hw_irq.h            |   16 +++
 arch/x86/include/asm/trace/irq_vectors.h |  159 ++++++++++++++++++++++++++++++
 arch/x86/kernel/Makefile                 |    1 +
 arch/x86/kernel/apic/apic.c              |   71 +++++++++++---
 arch/x86/kernel/cpu/mcheck/therm_throt.c |   24 ++++-
 arch/x86/kernel/cpu/mcheck/threshold.c   |   24 ++++-
 arch/x86/kernel/entry_32.S               |   12 ++-
 arch/x86/kernel/entry_64.S               |   27 ++++-
 arch/x86/kernel/head_64.S                |    6 +
 arch/x86/kernel/irq.c                    |   31 ++++--
 arch/x86/kernel/irq_work.c               |   24 ++++-
 arch/x86/kernel/smp.c                    |   65 +++++++++++--
 arch/x86/kernel/tracepoint.c             |   61 ++++++++++++
 include/linux/tracepoint.h               |    2 +
 include/trace/define_trace.h             |    5 +
 include/trace/ftrace.h                   |    4 +
 include/xen/events.h                     |    3 +
 20 files changed, 546 insertions(+), 54 deletions(-)
 create mode 100644 arch/x86/include/asm/trace/irq_vectors.h
 create mode 100644 arch/x86/kernel/tracepoint.c
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists