[PATCH 1/5] trace-cmd: Remove ts offset from tsc2nsec conversion

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

Do not get, store and use offset when converting TSC to nanoseconds.
The logic for automatically detecting the TSC offset is not stable enough
and could introduce errors, which leads to problems when reading trace
files in some use cases. The offset is not mandatory for tsc2nsec
conversion.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/trace-input.c |  1 -
 tracecmd/trace-record.c     | 62 -------------------------------------
 2 files changed, 63 deletions(-)

diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index a00fa982..e8a257db 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -1319,7 +1319,6 @@ static unsigned long long timestamp_calc(unsigned long long ts, int cpu,
 		ts *= handle->ts2secs;
 	} else if (handle->tsc_calc.mult) {
 		/* auto calculated TSC clock frequency */
-		ts -= handle->tsc_calc.offset;
 		ts = mul_u64_u32_shr(ts, handle->tsc_calc.mult, handle->tsc_calc.shift);
 	}
 
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index fd03a605..d732b394 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -6483,65 +6483,6 @@ static bool has_local_instances(void)
 	return false;
 }
 
-/*
- * Get the current clock value
- */
-#define CLOCK_INST_NAME	"_clock_instance_"
-static unsigned long long get_clock_now(const char *clock)
-{
-	struct tracefs_instance *ts_instance = NULL;
-	unsigned long long ts = 0;
-	struct tep_handle *tep;
-	int tfd;
-	int ret;
-
-	/* Set up a tep to read the raw format */
-	tep = get_ftrace_tep();
-	if (!tep)
-		return 0;
-	ts_instance = tracefs_instance_create(CLOCK_INST_NAME);
-	if (!ts_instance)
-		goto out;
-	if (clock) {
-		ret = tracefs_instance_file_write(ts_instance, "trace_clock", clock);
-		if (ret < strlen(clock))
-			goto out;
-	}
-	tfd = tracefs_instance_file_open(ts_instance, "trace_marker", O_WRONLY);
-	if (tfd < 0)
-		goto out;
-	tracefs_trace_on(ts_instance);
-	ret = write(tfd, STAMP, 5);
-	tracefs_trace_off(ts_instance);
-	ts = find_time_stamp(tep, ts_instance);
-	close(tfd);
-
-out:
-	if (ts_instance) {
-		if (tracefs_instance_is_new(ts_instance))
-			tracefs_instance_destroy(ts_instance);
-		tracefs_instance_free(ts_instance);
-	}
-	tep_free(tep);
-
-	return ts;
-}
-
-static void get_tsc_offset(struct common_record_context *ctx)
-{
-	struct buffer_instance *instance;
-
-	for_all_instances(instance) {
-		if (is_guest(instance) || !instance->clock)
-			continue;
-
-		ctx->tsc2nsec.offset = get_clock_now(instance->clock);
-		return;
-	}
-
-	ctx->tsc2nsec.offset = get_clock_now(NULL);
-}
-
 static void set_tsync_params(struct common_record_context *ctx)
 {
 	struct buffer_instance *instance;
@@ -6566,7 +6507,6 @@ static void set_tsync_params(struct common_record_context *ctx)
 				die("Cannot not allocate clock");
 			ctx->tsc2nsec.mult = mult;
 			ctx->tsc2nsec.shift = shift;
-			ctx->tsc2nsec.offset = get_clock_now(TSC_CLOCK);
 			force_tsc = true;
 		} else { /* Use the current clock of the first host instance */
 			clock = get_trace_clock(true);
@@ -6661,8 +6601,6 @@ static void record_trace(int argc, char **argv,
 	for_all_instances(instance)
 		set_clock(instance);
 
-	if (ctx->tsc2nsec.mult)
-		get_tsc_offset(ctx);
 
 	/* Record records the date first */
 	if (ctx->date &&
-- 
2.30.2