[PATCH v16 0/4] trace,x86: irq vector tracepoint support

From: Seiji Aguchi
Date: Tue Jun 18 2013 - 14:59:23 EST

Change log
v15 -> v16
- Patch 4/4
- Define trace_uv_bau_message_intr1 in case of CONFIG_TRACING=y
to build with SGI UV support successfully.
- Define trace_hyperv_callback_vector only when CONFIG_TRACING
is enabled.
v14 -> v15
- Patch 2/4
Introduce non-trace irq handlers with entering/exiting_irq()
by separating it from previous "patch v14 3/3".

- Patch 3/4
Separate a patch renaming variables for debugging and introducing
load_current_idt() from previous "patch v14 3/3".

- Patch 4/4
Introduce load_current_idt() to cpu_init() for i386 to handle cpu-hotplug.

v13 -> v14
- Rebase to 3.10-rc4
- Patch 3/3
- Add comments above load_current_idt() in arch/x86/include/asm/desc.h.
- Introduce a logic selecting IDT that we currently should be using,
based on the current state instead of current_idt_desc_ptr.
- Rename some "nmi" variables to "debug".
- Introduce local_irq_save/restore() in load_current_idt() to avoid races
regardless of process/interrupt context.

v12 -> v13
- Rebase to 3.10-rc3
- Patch 2/3
- Separate a patch introducing entering/exiting_irq() from patch-v12 3/3.
- Patch 3/3
- Introduce write_trace_idt_entry() to remove "ifdef CONFIG_TRACING"
from _set_gate().
- Change DEFINE_IRQ_VECTOR_EVENT to save on repeat code.
- Add a path of irq_vector.h to Makefile.
- Introduce current_idt_descr_ptr and load_current_idt() to switch
IDT in a generic way with handling Debug traps/NMI and cpu hotplug.

v11 -> v12
- Rebase to 3.9-rc5

v10 -> v11
- Rebase to 3.9-rc2
- Add a modification for hyperv_callback vector. (patch 2/3)
- Change a way to switch idt to check the table in use instead of saving/restoring it,
because saving/restoring functions will break if we have to add another one. (patch 2/3)

v9 -> v10
- Add an explanation the reason why tracepoints has to place inside irq enter/exit handling. (patch 3/3)

v8 -> v9
- Rebase to 3.8-rc6
- Add Steven's email address at the top of the message and
move my signed-off-by below Steven's one because it is
originally created by Steven. (patch 1/3)
- Introduce a irq_vector_mutex to avoid a race at registering/unregistering
time. (patch 2/3)
- Use a per_cpu data to orig_idt_descr because IDT descritor is needed to each cpu
and the appropriate data type is per_cpu data. It is suggested by Steven.
(patch 2/3)

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

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.


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.

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

Seiji Aguchi (3):
trace,x86: Introduce entering/exiting_irq()
x86: Rename variables for debugging
trace,x86: Add irq vector tracepoints

Steven Rostedt (1):
tracing: Add DEFINE_EVENT_FN() macro

arch/x86/include/asm/apic.h | 27 +++++++
arch/x86/include/asm/desc.h | 119 ++++++++++++++++++++++++++++-
arch/x86/include/asm/entry_arch.h | 8 +-
arch/x86/include/asm/hw_irq.h | 17 ++++
arch/x86/include/asm/mshyperv.h | 3 +
arch/x86/include/asm/trace/irq_vectors.h | 104 ++++++++++++++++++++++++++
arch/x86/include/asm/uv/uv_bau.h | 3 +
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/apic/Makefile | 1 +
arch/x86/kernel/apic/apic.c | 71 +++++++++++++++---
arch/x86/kernel/cpu/common.c | 20 +++---
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 | 31 ++++++--
arch/x86/kernel/head_64.S | 8 ++-
arch/x86/kernel/irq.c | 31 +++++---
arch/x86/kernel/irq_work.c | 24 ++++++-
arch/x86/kernel/smp.c | 65 ++++++++++++++--
arch/x86/kernel/tracepoint.c | 57 ++++++++++++++
arch/x86/kernel/traps.c | 2 +-
include/linux/tracepoint.h | 2 +
include/trace/define_trace.h | 5 +
include/trace/ftrace.h | 4 +
include/xen/events.h | 3 +
25 files changed, 594 insertions(+), 72 deletions(-)
create mode 100644 arch/x86/include/asm/trace/irq_vectors.h
create mode 100644 arch/x86/kernel/tracepoint.c

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