RE: [PATCH v12 0/3] trace,x86: irq vector tracepoint support

[Seiji Aguchi]

Steven, Peter

When can I get feedback?

Seiji

> -----Original Message-----
> From: Seiji Aguchi
> Sent: Friday, April 05, 2013 3:16 PM
> To: linux-kernel@xxxxxxxxxxxxxxx; x86@xxxxxxxxxx; rostedt@xxxxxxxxxxx; hpa@xxxxxxxxx
> Cc: Thomas Gleixner (tglx@xxxxxxxxxxxxx); 'mingo@xxxxxxx' (mingo@xxxxxxx); Borislav Petkov (bp@xxxxxxxxx); linux-
> edac@xxxxxxxxxxxxxxx; Luck, Tony (tony.luck@xxxxxxxxx); dle-develop@xxxxxxxxxxxxxxxxxxxxx; Tomoki Sekiyama
> Subject: [PATCH v12 0/3] trace,x86: irq vector tracepoint support
> 
> Change log
>  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.
>    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 (2):
>   trace,x86: add x86 irq vector tracepoints
>   trace,x86: code-sharing between non-trace and trace irq handlers
> 
> Steven Rostedt (1):
>   tracing: Add DEFINE_EVENT_FN() macro
> 
>  arch/x86/include/asm/apic.h              |   27 +++++
>  arch/x86/include/asm/desc.h              |   36 +++++++-
>  arch/x86/include/asm/entry_arch.h        |    5 +-
>  arch/x86/include/asm/hw_irq.h            |   16 +++
>  arch/x86/include/asm/mshyperv.h          |    1 +
>  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/common.c             |   12 ++-
>  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               |   29 +++++-
>  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             |   71 +++++++++++++
>  include/linux/tracepoint.h               |    2 +
>  include/trace/define_trace.h             |    5 +
>  include/trace/ftrace.h                   |    4 +
>  include/xen/events.h                     |    3 +
>  22 files changed, 570 insertions(+), 58 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@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/