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Re: [Qemu-devel] [PATCH v2 0/2] trace: fix trace_event_get_state() for S
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v2 0/2] trace: fix trace_event_get_state() for SystemTap and LTTng UST |
Date: |
Tue, 1 Aug 2017 10:38:57 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
On Mon, Jul 31, 2017 at 03:07:16PM +0100, Stefan Hajnoczi wrote:
> v2:
> * Don't special-case QEMU dstate [Daniel Berrange]
> * Use _backends() postfix to clarify function purpose [LluĂs]
>
> Trace events that compute their arguments can affect performance. The
> following idom can be used to avoid computing arguments when the trace event
> is
> disabled:
>
> if (trace_event_get_state(TRACE_MY_EVENT)) {
> char *str = g_strdup_printf("Expensive string ...", ...);
> trace_my_event(str);
> g_free(str);
> }
>
> Unfortunately this breaks the trace event for SystemTap and LTTng UST since
> those tracers manage their own enabled/disabled state.
>
> These patches add per-backend dstate to trace_event_get_state() so that the
> trace event fires as expected when enabled via SystemTap or LTTng UST.
>
> Stefan Hajnoczi (2):
> trace: add TRACE_<event>_BACKEND_DSTATE()
> trace: add trace_event_get_state_backends()
>
> docs/devel/tracing.txt | 2 +-
> trace/control.h | 18 +++++++++++++++++-
> hw/usb/hcd-ohci.c | 13 +++++--------
> net/colo-compare.c | 11 ++++++-----
> net/filter-rewriter.c | 4 ++--
> scripts/tracetool/__init__.py | 1 +
> scripts/tracetool/backend/__init__.py | 3 +++
> scripts/tracetool/backend/dtrace.py | 12 ++++++++++++
> scripts/tracetool/backend/ftrace.py | 5 +++++
> scripts/tracetool/backend/log.py | 5 +++++
> scripts/tracetool/backend/simple.py | 5 +++++
> scripts/tracetool/backend/syslog.py | 5 +++++
> scripts/tracetool/backend/ust.py | 5 +++++
> scripts/tracetool/format/h.py | 10 ++++++++++
> 14 files changed, 82 insertions(+), 17 deletions(-)
>
> --
> 2.13.3
>
>
Thanks, applied to my tracing tree:
https://github.com/stefanha/qemu/commits/tracing
Stefan
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Stefan Hajnoczi <=