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Re: [Qemu-devel] [PATCH 3/3] Toggle tracepoint state
From: |
Luiz Capitulino |
Subject: |
Re: [Qemu-devel] [PATCH 3/3] Toggle tracepoint state |
Date: |
Wed, 9 Jun 2010 17:43:35 -0300 |
On Tue, 8 Jun 2010 12:38:58 +0530
Prerna Saxena <address@hidden> wrote:
> 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 <address@hidden>
> ---
> 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);
Monitor has a bool type, please take a look in do_set_link().
> + return;
Not needed, also true for other functions in this patch, suggest reading
CODING_STYLE for other style related issues in this series.
> +}
> +#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
> address@hidden 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
> address@hidden tracepoint
> address@hidden 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))