On 07/28/2017 12:20 PM, Stefan Hajnoczi wrote:
> 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: check backend dstate in trace_event_get_state()
>
> trace/control.h | 20 ++++++++++++++++++--
> scripts/tracetool/__init__.py | 1 +
> scripts/tracetool/backend/__init__.py | 3 +++
> scripts/tracetool/backend/dtrace.py | 12 ++++++++++++
> scripts/tracetool/backend/ftrace.py | 2 +-
> scripts/tracetool/backend/log.py | 3 ++-
> scripts/tracetool/backend/simple.py | 2 +-
> scripts/tracetool/backend/syslog.py | 3 ++-
> scripts/tracetool/backend/ust.py | 5 +++++
> scripts/tracetool/format/h.py | 10 ++++++++++
> 10 files changed, 55 insertions(+), 6 deletions(-)
>
looks good to me!
This also fixes the same issue not only in my code, but in
static void ohci_td_pkt(const char *msg, const uint8_t *buf, size_t len)
and in colo code.
Reviewed-by: Denis V. Lunev <d...@openvz.org>
