This patch adds support for dynamically enabling/disabling of tracepoints.
Monitor commands added :
1) info tracepoints : to view all available tracepoints and
their state.
2) tracepoint NAME on|off : to enable/disable data logging from a
given tracepoint.
Eg, tracepoint paio_submit off
disables logging of data when
paio_submit is hit.
At present this is done with a simple comparison -- there is scope
for optimizations that can be employed here to speed this up.
Signed-off-by: Prerna Saxena <prerna@xxxxxxxxxxxxxxxxxx>
---
monitor.c | 21 +++++++++++++++++++++
qemu-monitor.hx | 16 ++++++++++++++++
simpletrace.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
tracetool | 30 ++++++++++++++++++++++++++----
vl.c | 6 ++++++
5 files changed, 123 insertions(+), 5 deletions(-)
diff --git a/monitor.c b/monitor.c
index fda29aa..1e05b38 100644
--- a/monitor.c
+++ b/monitor.c
@@ -547,7 +547,19 @@ static void do_commit(Monitor *mon, const QDict *qdict)
bdrv_commit(dinfo->bdrv);
}
}
+#ifdef CONFIG_SIMPLE_TRACE
+static void do_change_tracepoint_state(Monitor *mon, const QDict *qdict)
+{
+ const char *tp_name = qdict_get_str(qdict, "name");
+ const char *tp_state = qdict_get_str(qdict, "option");
+ if (!strncmp(tp_state, "on", 2))
+ change_tracepoint_state(tp_name, 1);
+ if (!strncmp(tp_state, "off", 3))
+ change_tracepoint_state(tp_name, 0);
+ return;
+}
+#endif
static void user_monitor_complete(void *opaque, QObject *ret_data)
{
MonitorCompletionData *data = (MonitorCompletionData *)opaque;
@@ -2783,6 +2795,15 @@ static const mon_cmd_t info_cmds[] = {
.help = "show roms",
.mhandler.info = do_info_roms,
},
+#ifdef CONFIG_SIMPLE_TRACE
+ {
+ .name = "tracepoints",
+ .args_type = "",
+ .params = "",
+ .help = "show available tracepoints & their state",
+ .mhandler.info = do_info_all_tracepoints,
+ },
+#endif
{
.name = NULL,
},
diff --git a/qemu-monitor.hx b/qemu-monitor.hx
index c604aec..36481ea 100644
--- a/qemu-monitor.hx
+++ b/qemu-monitor.hx
@@ -114,6 +114,8 @@ show migration status
show balloon information
@item info qtree
show device tree
+@item info tracepoints
+show available tracepoints and their state
@end table
ETEXI
@@ -236,6 +238,20 @@ STEXI
@item trace
@findex trace
show contents of trace buffer
+ETEXI
+
+ {
+ .name = "tracepoint",
+ .args_type = "name:s,option:s",
+ .params = "name on|off",
+ .help = "changes status of a specific tracepoint",
+ .mhandler.cmd = do_change_tracepoint_state,
+ },
+
+STEXI
+@item tracepoint
+@findex tracepoint
+changes status of a tracepoint
#endif
ETEXI
diff --git a/simpletrace.c b/simpletrace.c
index 8f33a81..75d2fca 100644
--- a/simpletrace.c
+++ b/simpletrace.c
@@ -3,6 +3,12 @@
#include "trace.h"
typedef struct {
+ char *tp_name;
+ bool state;
+ unsigned int hash;
+} Tracepoint;
+
+typedef struct {
unsigned long event;
unsigned long x1;
unsigned long x2;
@@ -18,10 +24,24 @@ enum {
static TraceRecord trace_buf[TRACE_BUF_LEN];
static unsigned int trace_idx;
static FILE *trace_fp;
+static Tracepoint trace_list[NR_TRACEPOINTS];
+
+void init_tracepoint(const char *tname, TraceEvent tevent) {
+ if (!tname || tevent > NR_TRACEPOINTS)
+ return;
+
+ trace_list[tevent].tp_name = (char*)qemu_malloc(strlen(tname)+1);
+ strncpy(trace_list[tevent].tp_name, tname, strlen(tname));
+ trace_list[tevent].hash = tdb_hash(tname);
+ trace_list[tevent].state = 1; /* Enable all by default */
+ return;
+}
static void trace(TraceEvent event, unsigned long x1,
unsigned long x2, unsigned long x3,
unsigned long x4, unsigned long x5) {
+ if (!trace_list[event].state)
+ return;
TraceRecord *rec = &trace_buf[trace_idx];
rec->event = event;
rec->x1 = x1;
@@ -64,7 +84,7 @@ void trace5(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long
}
void do_info_trace(Monitor *mon) {
- static unsigned int i, max_idx;
+ unsigned int i, max_idx;
if (trace_idx)
max_idx = trace_idx;
@@ -77,3 +97,36 @@ void do_info_trace(Monitor *mon) {
trace_buf[i].x3, trace_buf[i].x4, trace_buf[i].x5);
return;
}
+
+void do_info_all_tracepoints(Monitor *mon) {
+ unsigned int i;
+ for (i=0; i<NR_TRACEPOINTS; i++)
+ monitor_printf(mon, "%s [Event ID %u] : state %u\n",
+ trace_list[i].tp_name, i, trace_list[i].state);
+ return;
+}
+
+static int find_tracepoint_by_name(const char *tname) {
+ unsigned int i, name_hash;
+
+ if (!tname)
+ return -1;
+
+ name_hash = tdb_hash(tname);
+
+ for (i=0; i<NR_TRACEPOINTS; i++)
+ if (trace_list[i].hash == name_hash &&
+ !strncmp(trace_list[i].tp_name, tname, strlen(tname)))
+ return i;
+ return -1; /* indicates end of list reached without a match */
+}
+
+void change_tracepoint_state(const char *tname, bool tstate) {
+ int i;
+
+ i = find_tracepoint_by_name(tname);
+ /* TODO : This update might need to be protected by a memory barrier */
+ if (i >= 0)
+ trace_list[i].state = tstate;
+ return;
+}
diff --git a/tracetool b/tracetool
index 6c15154..cc2b22c 100755
--- a/tracetool
+++ b/tracetool
@@ -123,14 +123,20 @@ linetoc_end_nop()
linetoh_begin_simple()
{
cat <<EOF
+#include <stdbool.h>
+
typedef unsigned int TraceEvent;
+void init_tracepoint_table(void);
+void init_tracepoint(const char *tname, TraceEvent tevent);
void trace1(TraceEvent event, unsigned long x1);
void trace2(TraceEvent event, unsigned long x1, unsigned long x2);
void trace3(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long x3);
void trace4(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long x3, unsigned long x4);
void trace5(TraceEvent 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_tracepoints(Monitor *mon);
+void change_tracepoint_state(const char *tname, bool tstate);
EOF
simple_event_num=0
@@ -163,22 +169,38 @@ EOF
linetoh_end_simple()
{
- return
+ cat <<EOF
+#define NR_TRACEPOINTS $simple_event_num
+EOF
}
linetoc_begin_simple()
{
- return
+ cat <<EOF
+#include "trace.h"
+
+void init_tracepoint_table(void) {
+EOF
+ simple_event_num=0
+
}
linetoc_simple()
{
- return
+ local name
+ name=$(get_name "$1")
+ cat <<EOF
+init_tracepoint("$name", $simple_event_num);
+EOF
+ simple_event_num=$((simple_event_num + 1))
}
linetoc_end_simple()
{
- return
+ cat <<EOF
+return;
+}
+EOF
}
linetoh_begin_ust()
diff --git a/vl.c b/vl.c
index 328395e..dd07904 100644
--- a/vl.c
+++ b/vl.c
@@ -163,6 +163,9 @@ int main(int argc, char **argv)
#include "cpus.h"
#include "arch_init.h"
+#ifdef CONFIG_SIMPLE_TRACE
+#include "trace.h"
+#endif
//#define DEBUG_NET
//#define DEBUG_SLIRP
@@ -3604,6 +3607,9 @@ int main(int argc, char **argv, char **envp)
if (net_init_clients() < 0) {
exit(1);
}
+#ifdef CONFIG_SIMPLE_TRACE
+ init_tracepoint_table();
+#endif
/* init the bluetooth world */
if (foreach_device_config(DEV_BT, bt_parse))
--
1.6.2.5
--
Prerna Saxena
Linux Technology Centre,
IBM Systems and Technology Lab,
Bangalore, India
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