Hollis Blanchard <hollis_blanch...@mentor.com> writes:
> Previously, trace record files (created by st_set_trace_file_enabled(true))
> were created by the simple backend at initialization time, even if no events
> were actually enabled.
>
> As a consequence, the working directory would become littered with trace-PID
> files just by enabling the simple backend at configure time, even when no
> -trace options were used.
>
> ---
> I've been using this to avoid creation of empty trace record files. I haven't
> done any scientific performance studies, but an extra function
> call/conditional/return when recording every trace event doesn't seem to have
> any noticeable effect.
>
> Signed-off-by: Hollis Blanchard <hollis_blanch...@mentor.com>
> ---
> trace/simple.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/trace/simple.c b/trace/simple.c
> index 3fdcc82..67ccc3c 100644
> --- a/trace/simple.c
> +++ b/trace/simple.c
> @@ -209,6 +209,8 @@ int trace_record_start(TraceBufferRecord *rec,
> TraceEventID event, size_t datasi
> uint64_t event_u64 = event;
> uint64_t timestamp_ns = get_clock();
>
> + st_set_trace_file_enabled(true);
> +
> do {
> old_idx = g_atomic_int_get(&trace_idx);
> smp_rmb();
> @@ -320,6 +322,7 @@ void st_set_trace_file_enabled(bool enable)
> */
> void st_set_trace_file(const char *file)
> {
> + /* Tracing will be re-enabled when the next event is written. */
> st_set_trace_file_enabled(false);
>
> g_free(trace_file_name);
> @@ -330,8 +333,6 @@ void st_set_trace_file(const char *file)
> } else {
> trace_file_name = g_strdup_printf("%s", file);
> }
> -
> - st_set_trace_file_enabled(true);
> }
This fixes the "make check" bug I reported:
http://lists.nongnu.org/archive/html/qemu-devel/2016-02/msg01811.html
because by not enabling the file it doesn't attempt to flush it before
the test has started. However as it is a side-effect of the patch there
may be a better solution. However have a:
Tested-by: Alex Bennée <alex.ben...@linaro.org>
--
Alex Bennée
