Monitor commands for 'simple' trace backend

This exports tdb_hash() for use by tracing framework.

Signed-off-by Prerna Saxena <[email protected]>

---
 qdict.c |    2 +-
 qdict.h |    2 ++
 2 files changed, 3 insertions(+), 1 deletions(-)

qdict.c +1 -1

index 175bc17..5261872 100644
@@ -56,7 +56,7 @@ QDict *qobject_to_qdict(const QObject *obj)
  * tdb_hash(): based on the hash agorithm from gdbm, via tdb
  * (from module-init-tools)
  */
-static unsigned int tdb_hash(const char *name)
+unsigned int tdb_hash(const char *name)
 {
     unsigned value;	/* Used to compute the hash value.  */
     unsigned   i;	/* Used to cycle through random values. */

qdict.h +2 -0

index 5e5902c..d221c18 100644
@@ -59,4 +59,6 @@ int64_t qdict_get_try_int(const QDict *qdict, const char *key,
                           int64_t err_value);
 const char *qdict_get_try_str(const QDict *qdict, const char *key);
 
+/* Export tdb_hash() for use by trace framework */
+unsigned int tdb_hash(const char *name);
 #endif /* QDICT_H */

Quoted 1 line · On Tue, 8 Jun 2010 12:31:38 +0530 Prerna Saxena<[email protected]>…

This exports tdb_hash() for use by tracing framework.

Suggest to rename it (eg. qemu_hash()) and move it to a better location, qdict
is not the best module to export such service.

This introduces the monitor command 'trace' to read current contents of trace buffer.

Signed-off-by Prerna Saxena <[email protected]>

---
 configure       |    3 +++
 monitor.c       |    3 +++
 qemu-monitor.hx |   16 ++++++++++++++++
 simpletrace.c   |   15 +++++++++++++++
 tracetool       |    4 ++++
 5 files changed, 41 insertions(+), 0 deletions(-)

configure +3 -0

index 675d0fc..56af8dd 100755
@@ -2302,6 +2302,9 @@ bsd)
 esac
 
 echo "TRACE_BACKEND=$trace_backend" >> $config_host_mak
+if test "$trace_backend" = "simple"; then
+  echo "CONFIG_SIMPLE_TRACE=y" >> $config_host_mak
+fi
 if test "$trace_backend" = "ust"; then
   LIBS="-lust $LIBS"
 fi

monitor.c +3 -0

index ad50f12..fda29aa 100644
@@ -55,6 +55,9 @@
 #include "json-streamer.h"
 #include "json-parser.h"
 #include "osdep.h"
+#ifdef CONFIG_SIMPLE_TRACE
+#include "trace.h"
+#endif
 
 //#define DEBUG
 //#define DEBUG_COMPLETION

qemu-monitor.hx +16 -0

index b6e3467..c604aec 100644
@@ -221,6 +221,22 @@ STEXI
 @item logfile @var{filename}
 @findex logfile
 Output logs to @var{filename}.
+#ifdef CONFIG_SIMPLE_TRACE
+ETEXI
+
+    {
+        .name       = "trace",
+        .args_type  = "",
+        .params     = "",
+        .help       = "shows contents of trace buffer",
+        .mhandler.cmd = do_info_trace,
+    },
+
+STEXI
+@item trace
+@findex trace
+show contents of trace buffer
+#endif
 ETEXI
 
     {

simpletrace.c +0 -0

index 2fec4d3..8f33a81 100644

simpletrace.c +1 -0

+}

tracetool +4 -0

index 9ea9c08..6c15154 100755
@@ -130,6 +130,7 @@ 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);
 EOF
 
     simple_event_num=0

@@ -289,6 +290,9 @@ tracetoh()
 #define TRACE_H
 
 #include "qemu-common.h"
+
+extern void monitor_printf(Monitor *mon, const char *fmt, ...)
+    __attribute__ ((__format__ (__printf__, 2, 3)));
 EOF
     convert h
     echo "#endif /* TRACE_H */"

Quoted 3 lines · On Tue, 8 Jun 2010 12:34:37 +0530 Prerna Saxena<[email protected]>…

This introduces the monitor command 'trace' to read current contents of trace buffer.

simpletrace.c void trace4(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long · line 66

Quoted 11 lines

...

simpletrace.c +2 -0

index 2fec4d3..8f33a81 100644
@@ -62,3 +62,18 @@ void trace4(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long
  void trace5(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long x3, unsigned long x4, unsigned long x5) {
      trace(event, x1, x2, x3, x4, x5);
  }
+
+void do_info_trace(Monitor *mon) {

You sure this shouldn't be 'info trace'?

simpletrace.c void trace4(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long · line 67

Quoted 2 lines

simpletrace.c +1 -0

+    static unsigned int i, max_idx;

Why static?

simpletrace.c void trace4(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long · line 72

Quoted 6 lines

simpletrace.c +5 -0

+
+    if (trace_idx)
+        max_idx = trace_idx;
+    else
+        max_idx = TRACE_BUF_LEN;

  max_idx = trace_idx ? trace_idx : TRACE_BUF_LEN;

simpletrace.c void trace4(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long · line 77

Quoted 5 lines

simpletrace.c +5 -0

+
+    for (i=0; i<max_idx ;i++)
+        monitor_printf(mon, "Event %ld : %ld %ld %ld %ld %ld\n",
+	trace_buf[i].event, trace_buf[i].x1, trace_buf[i].x2,
+	trace_buf[i].x3, trace_buf[i].x4, trace_buf[i].x5);

Style& indentation.

simpletrace.c void trace4(TraceEvent event, unsigned long x1, unsigned long x2, unsigned long · line 78

Quoted 2 lines

simpletrace.c +1 -0

+    return;

Not needed.

Quoted 4 lines

simpletrace.c +1 -0

+}

tracetool +0 -0

....

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 <[email protected]>

---
 monitor.c       |   21 +++++++++++++++++++++
 qemu-monitor.hx |   16 ++++++++++++++++
 simpletrace.c   |   55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 tracetool       |   30 ++++++++++++++++++++++++++----
 vl.c            |    6 ++++++
 5 files changed, 123 insertions(+), 5 deletions(-)

monitor.c +0 -0

index fda29aa..1e05b38 100644
@@ -547,7 +547,19 @@ static void do_commit(Monitor *mon, const QDict *qdict)
         bdrv_commit(dinfo->bdrv);
     }
 }

monitor.c +11 -0

+}
+#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,
     },

qemu-monitor.hx +16 -0

index c604aec..36481ea 100644
@@ -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
 

simpletrace.c +54 -1

index 8f33a81..75d2fca 100644
@@ -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;
+}

tracetool +26 -4

index 6c15154..cc2b22c 100755
@@ -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()

vl.c +6 -0

index 328395e..dd07904 100644
@@ -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))

Quoted 4 lines · On Tue, 8 Jun 2010 12:38:58 +0530 Prerna Saxena<[email protected]>…

This patch adds support for dynamically enabling/disabling of tracepoints. Monitor commands added :
....

Monitor has a bool type, please take a look in do_set_link().

Quoted 1 line

+ return;

Not needed, also true for other functions in this patch, suggest reading
CODING_STYLE for other style related issues in this series.

Quoted 3 lines

....