Re: [Qemu-devel] [PATCH v2 00/10] trace: Per-vCPU tracing states

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Tue, Nov 24, 2015 at 06:08:47PM +0100, Lluís Vilanova wrote:
> NOTE: This series completes the framework for guest code tracing. Next series
>       will add actual events.
> 
> Provides per-vCPU dynamic controls of the tracing state of events tied to a
> specific virtual CPU.
> 
> Events with the "vcpu" property are identified as being tied to a particular
> virtual CPU, like executing an instruction. The state of such events can be
> controlled idependently; this is specially useful to, for example, trace memory
> access events of a process executing on a specific virtual CPU.
> 
> This event property plays in combination with the "tcg" property to avoid
> generating a call to the execution-time event tracer when a vCPU is not actively
> tracing such event (i.e., avoids adding tracing overheads).
> 
> Virtual CPUs tracing the same set of events use the same physical translation
> cache, improving their reuse. The system has 2^N physical translation caches,
> where "N" is the number of TCG events with the "vcpu" property. Every vCPU has a
> bitmap with the states of these events, which can be controlled separately, and
> uses it to select its physical translation cache. At translation time, QEMU
> generates the code to trace an event at execution time only if the event is
> enabled.
> 
> Changes in v2
> =============
> 
> * Rebase on 5522a84.
> * Improve patch descriptions.
> * Refactor code generation into a separate patch.
> * Fix forward declarations (Stefan Hajnoczi & Eduardo Habkost).
> * Fix "since" tags in QAPI interface (Eric Blake).
> * Unify QAPI/QMP interface with an optional 'vcpu' argument (Eric Blake).
> * Fix QMP+GTK header workaround (Stefan Hajnoczi).
> 
> 
> Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
> ---
> 
> Lluís Vilanova (10):
>       trace: Add support for vCPU pointers in trace events
>       trace: Add 'vcpu' event property
>       trace: [tcg] Identify events with the 'vcpu' property
>       exec: [tcg] Refactor flush of per-CPU virtual TB cache
>       exec: [ŧcg] Use multiple physical TB caches
>       exec: [tcg] Track which vCPU is performing translation and execution
>       [trivial] Track when QEMU has finished initialization
>       disas: Remove unused macro '_'
>       trace: [tcg] Add per-vCPU tracing states for events with the 'vcpu' property
>       trace: [tcg] Generate TCG code to trace guest events on a per-vCPU basis
> 
> 
>  Makefile.objs                            |    3 -
>  bsd-user/main.c                          |    1 
>  cpu-exec.c                               |   17 +++
>  cputlb.c                                 |    2 
>  disas/i386.c                             |    2 
>  docs/tracing.txt                         |   40 ++++++++
>  include/disas/bfd.h                      |    1 
>  include/exec/exec-all.h                  |   16 +++
>  include/qemu-common.h                    |    3 +
>  include/qemu/typedefs.h                  |    1 
>  include/qom/cpu.h                        |   10 ++
>  linux-user/main.c                        |    1 
>  monitor.c                                |    4 -
>  qapi/trace.json                          |   16 ++-
>  qemu-common.c                            |   14 +++
>  qmp-commands.hx                          |   17 +++
>  qom/cpu.c                                |   21 ++++
>  scripts/tracetool/__init__.py            |   24 ++++-
>  scripts/tracetool/format/events_c.py     |   11 ++
>  scripts/tracetool/format/events_h.py     |   14 ++-
>  scripts/tracetool/format/h.py            |    4 +
>  scripts/tracetool/format/tcg_h.py        |   21 +++-
>  scripts/tracetool/format/tcg_helper_c.py |   11 ++
>  scripts/tracetool/format/ust_events_c.py |    3 -
>  scripts/tracetool/transform.py           |    9 ++
>  stubs/Makefile.objs                      |    1 
>  stubs/qemu-common-stub.c                 |   21 ++++
>  target-alpha/translate.c                 |    3 -
>  target-arm/translate.c                   |    3 -
>  target-arm/translate.h                   |    2 
>  target-cris/translate.c                  |    3 -
>  target-cris/translate_v10.c              |    1 
>  target-i386/translate.c                  |    3 -
>  target-lm32/translate.c                  |    3 -
>  target-m68k/translate.c                  |    3 -
>  target-microblaze/translate.c            |    3 -
>  target-mips/translate.c                  |    3 -
>  target-moxie/translate.c                 |    3 -
>  target-openrisc/translate.c              |    3 -
>  target-ppc/translate.c                   |    3 -
>  target-s390x/translate.c                 |    3 -
>  target-sh4/translate.c                   |    3 -
>  target-sparc/translate.c                 |    6 +
>  target-tilegx/translate.c                |    3 -
>  target-tricore/translate.c               |    3 -
>  target-unicore32/translate.c             |    3 -
>  target-xtensa/translate.c                |    3 -
>  tcg/tcg-op.h                             |    2 
>  tcg/tcg.h                                |   10 ++
>  trace/Makefile.objs                      |    2 
>  trace/control-internal.h                 |   21 +++-
>  trace/control-stub.c                     |   29 ++++++
>  trace/control-target.c                   |   69 +++++++++++++
>  trace/control.h                          |   64 ++++++++++++
>  trace/event-internal.h                   |    6 +
>  trace/qmp.c                              |  139 ++++++++++++++++++++++-----
>  translate-all.c                          |  156 ++++++++++++++++++++++++++----
>  translate-all.h                          |   49 +++++++++
>  vl.c                                     |    2 
>  59 files changed, 788 insertions(+), 109 deletions(-)
>  create mode 100644 qemu-common.c
>  create mode 100644 stubs/qemu-common-stub.c
>  create mode 100644 trace/control-stub.c
>  create mode 100644 trace/control-target.c
> 
> 
> To: qemu-devel@nongnu.org
> Cc: Stefan Hajnoczi <stefanha@gmail.com>
> Cc: Eduardo Habkost <ehabkost@redhat.com>
> Cc: Eric Blake <eblake@redhat.com>

Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

I left comments on individual patches.

There hasn't been any review from TCG folks yet.  I have CCed Peter
Maydell and Richard Henderson to review the TCG changes.

Stefan

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