This patch adds support for dynamically enabling/disabling of trace events.
This is done by internally maintaining each trace event's state, and
permitting logging of data from a trace event only if it is in an
'active' state.
Monitor commands added :
1) info trace-events : to view all available trace events and
their state.
2) trace-event NAME on|off : to enable/disable data logging from a
given trace event.
Eg, trace-event paio_submit off
disables logging of data when
paio_submit is hit.
By default, all trace-events are disabled. One can enable desired trace-events
via the monitor.
Signed-off-by: Prerna Saxena <prerna@xxxxxxxxxxxxxxxxxx>
---
monitor.c | 16 ++++++++++++++++
qemu-monitor.hx | 18 ++++++++++++++++++
simpletrace.c | 41 +++++++++++++++++++++++++++++++++++++++++
tracetool | 33 +++++++++++++++++++++++++++++----
4 files changed, 104 insertions(+), 4 deletions(-)
diff --git a/monitor.c b/monitor.c
index 8b60830..19b1ed7 100644
--- a/monitor.c
+++ b/monitor.c
@@ -548,6 +548,15 @@ static void do_commit(Monitor *mon, const QDict *qdict)
}
}
+#ifdef CONFIG_SIMPLE_TRACE
+static void do_change_trace_event_state(Monitor *mon, const QDict *qdict)
+{
+ const char *tp_name = qdict_get_str(qdict, "name");
+ bool new_state = qdict_get_bool(qdict, "option");
+ change_trace_event_state(tp_name, new_state);
+}
+#endif
+
static void user_monitor_complete(void *opaque, QObject *ret_data)
{
MonitorCompletionData *data = (MonitorCompletionData *)opaque;
@@ -2791,6 +2800,13 @@ static const mon_cmd_t info_cmds[] = {
.help = "show current contents of trace buffer",
.mhandler.info = do_info_trace,
},
+ {
+ .name = "trace-events",
+ .args_type = "",
+ .params = "",
+ .help = "show available trace-events & their state",
+ .mhandler.info = do_info_all_trace_events,
+ },
#endif
{
.name = NULL,
diff --git a/qemu-monitor.hx b/qemu-monitor.hx
index 766c30f..0fedcf9 100644
--- a/qemu-monitor.hx
+++ b/qemu-monitor.hx
@@ -117,6 +117,8 @@ show device tree
#ifdef CONFIG_SIMPLE_TRACE
@item info trace
show contents of trace buffer
+@item info trace-events
+show available trace events and their state
#endif
@end table
ETEXI
@@ -225,6 +227,22 @@ STEXI
@item logfile @var{filename}
@findex logfile
Output logs to @var{filename}.
+#ifdef CONFIG_SIMPLE_TRACE
+ETEXI
+
+ {
+ .name = "trace-event",
+ .args_type = "name:s,option:b",
+ .params = "name on|off",
+ .help = "changes status of a specific trace event",
+ .mhandler.cmd = do_change_trace_event_state,
+ },
+
+STEXI
+@item trace-event
+@findex trace-event
+changes status of a trace event
+#endif
ETEXI
{
diff --git a/simpletrace.c b/simpletrace.c
index 5734d15..57c41fc 100644
--- a/simpletrace.c
+++ b/simpletrace.c
@@ -24,6 +24,11 @@ static void trace(TraceEventID event, unsigned long x1,
unsigned long x2, unsigned long x3,
unsigned long x4, unsigned long x5) {
TraceRecord *rec = &trace_buf[trace_idx];
+
+ if (!trace_list[event].state) {
+ return;
+ }
+
rec->event = event;
rec->x1 = x1;
rec->x2 = x2;
@@ -74,3 +79,39 @@ void do_info_trace(Monitor *mon)
trace_buf[i].x3, trace_buf[i].x4, trace_buf[i].x5);
}
}
+
+void do_info_all_trace_events(Monitor *mon)
+{
+ unsigned int i;
+
+ for (i = 0; i < NR_TRACE_EVENTS; i++) {
+ monitor_printf(mon, "%s [Event ID %u] : state %u\n",
+ trace_list[i].tp_name, i, trace_list[i].state);
+ }
+}
+
+static TraceEvent* find_trace_event_by_name(const char *tname)
+{
+ unsigned int i;
+
+ if (!tname) {
+ return NULL;
+ }
+
+ for (i = 0; i < NR_TRACE_EVENTS; i++) {
+ if (!strcmp(trace_list[i].tp_name, tname)) {
+ return &trace_list[i];
+ }
+ }
+ return NULL; /* indicates end of list reached without a match */
+}
+
+void change_trace_event_state(const char *tname, bool tstate)
+{
+ TraceEvent *tp;
+
+ tp = find_trace_event_by_name(tname);
+ if (tp) {
+ tp->state = tstate;
+ }
+}
diff --git a/tracetool b/tracetool
index 6f8f8a9..9e8dbd8 100755
--- a/tracetool
+++ b/tracetool
@@ -123,14 +123,23 @@ linetoc_end_nop()
linetoh_begin_simple()
{
cat <<EOF
+#include <stdbool.h>
+
typedef unsigned int TraceEventID;
+typedef struct {
+ const char *tp_name;
+ bool state;
+} TraceEvent;
+
void trace1(TraceEventID event, unsigned long x1);
void trace2(TraceEventID event, unsigned long x1, unsigned long x2);
void trace3(TraceEventID event, unsigned long x1, unsigned long x2, unsigned long x3);
void trace4(TraceEventID event, unsigned long x1, unsigned long x2, unsigned long x3, unsigned long x4);
void trace5(TraceEventID event, unsigned long x1, unsigned long x2, unsigned long x3, unsigned long x4, unsigned long x5);
void do_info_trace(Monitor *mon);
+void do_info_all_trace_events(Monitor *mon);
+void change_trace_event_state(const char *tname, bool tstate);
EOF
simple_event_num=0
@@ -163,22 +172,38 @@ EOF
linetoh_end_simple()
{
- return
+ cat <<EOF
+#define NR_TRACE_EVENTS $simple_event_num
+extern TraceEvent trace_list[NR_TRACE_EVENTS];
+EOF
}
linetoc_begin_simple()
{
- return
+ cat <<EOF
+#include "trace.h"
+
+TraceEvent trace_list[] = {
+EOF
+ simple_event_num=0
+
}
linetoc_simple()
{
- return
+ local name
+ name=$(get_name "$1")
+ cat <<EOF
+{.tp_name = "$name", .state=0},
+EOF
+ simple_event_num=$((simple_event_num + 1))
}
linetoc_end_simple()
{
- return
+ cat <<EOF
+};
+EOF
}
linetoh_begin_ust()
--
1.6.2.5
--
Prerna Saxena
Linux Technology Centre,
IBM Systems and Technology Lab,
Bangalore, India
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
