In a host-guest tracing session, if there is no user configured tracing
clock, use TSC by default if following conditions are met:
- tsc-x86 trace clock is available on the host
- params for tsc to nanosecond conversion can be retrieved using
perf interface of the Liunx kernel - miltiplier and shift
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
---
tracecmd/trace-record.c | 97 ++++++++++++++++++++++++++++-------------
1 file changed, 67 insertions(+), 30 deletions(-)
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 4e4ad127..d794f1af 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -198,8 +198,10 @@ struct common_record_context {
const char *output;
char *date2ts;
char *user;
+ const char *clock;
struct tsc_nsec tsc2nsec;
int data_flags;
+ int tsync_loop_interval;
int record_all;
int total_disable;
@@ -3708,7 +3710,8 @@ static int open_guest_fifos(const char *guest, int **fds)
return i;
}
-static int host_tsync(struct buffer_instance *instance,
+static int host_tsync(struct common_record_context *ctx,
+ struct buffer_instance *instance,
unsigned int tsync_port, char *proto)
{
struct trace_guest *guest;
@@ -3723,14 +3726,15 @@ static int host_tsync(struct buffer_instance *instance,
instance->tsync_loop_interval,
instance->cid, tsync_port,
guest->pid, guest->cpu_max,
- proto, top_instance.clock);
+ proto, ctx->clock);
if (!instance->tsync)
return -1;
return 0;
}
-static void connect_to_agent(struct buffer_instance *instance)
+static void connect_to_agent(struct common_record_context *ctx,
+ struct buffer_instance *instance)
{
struct tracecmd_tsync_protos *protos = NULL;
int sd, ret, nr_fifos, nr_cpus, page_size;
@@ -3783,7 +3787,7 @@ static void connect_to_agent(struct buffer_instance *instance)
printf("Negotiated %s time sync protocol with guest %s\n",
tsync_protos_reply,
instance->name);
- host_tsync(instance, tsync_port, tsync_protos_reply);
+ host_tsync(ctx, instance, tsync_port, tsync_protos_reply);
} else
warning("Failed to negotiate timestamps synchronization with the guest");
}
@@ -3862,7 +3866,7 @@ void start_threads(enum trace_type type, struct common_record_context *ctx)
for_all_instances(instance) {
/* Start the connection now to find out how many CPUs we need */
if (is_guest(instance))
- connect_to_agent(instance);
+ connect_to_agent(ctx, instance);
total_cpu_count += instance->cpu_count;
}
@@ -4128,6 +4132,7 @@ enum {
DATA_FL_NONE = 0,
DATA_FL_DATE = 1,
DATA_FL_OFFSET = 2,
+ DATA_FL_GUEST = 4,
};
static void add_options(struct tracecmd_output *handle, struct common_record_context *ctx)
@@ -5812,7 +5817,6 @@ static void parse_record_options(int argc,
int name_counter = 0;
int negative = 0;
struct buffer_instance *instance, *del_list = NULL;
- bool guest_sync_set = false;
int do_children = 0;
int fpids_count = 0;
@@ -5947,6 +5951,7 @@ static void parse_record_options(int argc,
ctx->instance->port = port;
ctx->instance->name = name;
add_instance(ctx->instance, 0);
+ ctx->data_flags |= DATA_FL_GUEST;
break;
}
case 'F':
@@ -6008,8 +6013,8 @@ static void parse_record_options(int argc,
if (!ctx->instance->clock)
die("Failed allocation");
ctx->instance->flags |= BUFFER_FL_HAS_CLOCK;
- if (is_top_instance(ctx->instance))
- guest_sync_set = true;
+ if (!ctx->clock && !is_guest(ctx->instance))
+ ctx->clock = ctx->instance->clock;
break;
case 'v':
negative = 1;
@@ -6253,8 +6258,7 @@ static void parse_record_options(int argc,
break;
case OPT_tsyncinterval:
cmd_check_die(ctx, CMD_set, *(argv+1), "--tsync-interval");
- top_instance.tsync_loop_interval = atoi(optarg);
- guest_sync_set = true;
+ ctx->tsync_loop_interval = atoi(optarg);
break;
case OPT_fork:
if (!IS_START(ctx))
@@ -6288,26 +6292,6 @@ static void parse_record_options(int argc,
add_argv(instance, "--date", true);
}
}
- if (guest_sync_set) {
- /* If -C is specified, prepend clock to all guest VM flags */
- for_all_instances(instance) {
- if (top_instance.clock) {
- if (is_guest(instance) &&
- !(instance->flags & BUFFER_FL_HAS_CLOCK)) {
- add_argv(instance,
- (char *)top_instance.clock,
- true);
- add_argv(instance, "-C", true);
- if (!instance->clock) {
- instance->clock = strdup((char *)top_instance.clock);
- if (!instance->clock)
- die("Could not allocate instance clock");
- }
- }
- }
- instance->tsync_loop_interval = top_instance.tsync_loop_interval;
- }
- }
if (!ctx->filtered && ctx->instance->filter_mod)
add_func(&ctx->instance->filter_funcs,
@@ -6474,6 +6458,56 @@ static void get_tsc_offset(struct common_record_context *ctx)
ctx->tsc2nsec.offset = get_clock_now(NULL);
}
+static void set_tsync_params(struct common_record_context *ctx)
+{
+ const char *clock = ctx->clock;
+ struct buffer_instance *instance;
+ int shift, mult;
+ bool force_tsc = false;
+
+ /*
+ * If no clock is configured &&
+ * KVM time sync protocol is available &&
+ * tsc-x86 clock is supported &&
+ * TSC to nsec multiplier and shift are available:
+ * force using the x86-tsc clock for this host-guest tracing session
+ * and store TSC to nsec multiplier and shift.
+ */
+ if (!clock && tsync_proto_is_supported("kvm") &&
+ clock_is_supported(NULL, TSC_CLOCK) &&
+ !get_tsc_nsec(&shift, &mult) && mult) {
+ clock = TSC_CLOCK;
+ ctx->tsc2nsec.mult = mult;
+ ctx->tsc2nsec.shift = shift;
+ ctx->tsc2nsec.offset = get_clock_now(TSC_CLOCK);
+ force_tsc = true;
+ }
+
+ if (!clock && !ctx->tsync_loop_interval)
+ return;
+ for_all_instances(instance) {
+ if (clock && !(instance->flags & BUFFER_FL_HAS_CLOCK)) {
+ /* use the same clock in all tracing peers */
+ if (is_guest(instance)) {
+ if (!instance->clock) {
+ instance->clock = strdup(clock);
+ if (!instance->clock)
+ die("Can not allocate instance clock");
+ }
+ add_argv(instance, (char *)instance->clock, true);
+ add_argv(instance, "-C", true);
+ if (ctx->tsc2nsec.mult)
+ instance->flags |= BUFFER_FL_TSC2NSEC;
+ } else if (force_tsc && !instance->clock) {
+ instance->clock = strdup(clock);
+ if (!instance->clock)
+ die("Can not allocate instance clock");
+ }
+ }
+ instance->tsync_loop_interval = ctx->tsync_loop_interval;
+ }
+}
+
/*
* This function contains common code for the following commands:
* record, start, stream, profile.
@@ -6503,6 +6537,9 @@ static void record_trace(int argc, char **argv,
if (!ctx->output)
ctx->output = DEFAULT_INPUT_FILE;
+ if (ctx->data_flags & DATA_FL_GUEST)
+ set_tsync_params(ctx);
+
make_instances();
/* Save the state of tracing_on before starting */
--
2.30.2
|