Add TSC calibration support to ftcat

Provide the -c option to calibrate the TSC offsets.

Provide the -v option to get output about it.

2 files changed, 42 insertions, 5 deletions

diff --git a/include/timestamp.h b/include/timestamp.h
index b3b10ce..1668bcb 100644
--- a/include/timestamp.h
+++ b/include/timestamp.h
@@ -32,8 +32,9 @@ int  str2event(const char* str, cmd_t *id);
 const char* event2str(cmd_t id);
 const char* task_type2str(int task_type);
 
-#define ENABLE_CMD  0L
-#define DISABLE_CMD 1L
+#define ENABLE_CMD         0x0
+#define DISABLE_CMD        0x1
+#define CALIBRATE_CMD   0x1410
 
 #define TIMESTAMP(id) id
 
diff --git a/src/ftcat.c b/src/ftcat.c
index b43a3a5..b8c6f0c 100644
--- a/src/ftcat.c
+++ b/src/ftcat.c
@@ -26,6 +26,7 @@
 
 #include <sys/ioctl.h>
 
+#include "migration.h" /* from liblitmus */
 #include "timestamp.h"
 
 #define MAX_EVENTS 128
@@ -66,12 +67,35 @@ static int enable_event(int fd, char* str)
         err = ioctl(fd, ENABLE_CMD, *id);
 
         if (err < 0)
-                printf("ioctl(%d, %d, %d) => %d (errno: %d)\n", fd, (int) ENABLE_CMD, *id,
+                fprintf(stderr, "ioctl(%d, %d, %d) => %d (errno: %d)\n", fd, (int) ENABLE_CMD, *id,
                        err, errno);
 
         return err == 0;
 }
 
+static int calibrate_cycle_offsets(int fd)
+{
+        int cpu, err;
+        int max_cpus = sysconf(_SC_NPROCESSORS_CONF); 
+
+        for (cpu = 0; cpu < max_cpus; cpu++) {
+                err = be_migrate_to_cpu(cpu);
+                if (!err) {
+                        printf("Calibrating CPU %d...", cpu);
+                        err = ioctl(fd, CALIBRATE_CMD, 0);
+                        if (err) {
+                                printf("\n");
+                                fprintf(stderr, "ioctl(CALIBRATE_CMD) => %d (errno: %d, %m)\n", err, errno);
+                                return 0;
+                        } else
+                                printf(" done.\n");
+                } else {
+                        fprintf(stderr, "Could not migrate to CPU %d (%m).\n", cpu);
+                }
+        }
+        return 1;
+}
+
 
 static void cat2stdout(int fd)
 {
@@ -91,7 +115,9 @@ static void _usage(void)
         fprintf(stderr,
                 "Usage: ftcat [OPTIONS] <ft device> TS1 TS2 ....\n"
                 "\nOptions:\n"
-                "   -s SIZE   --  stop tracing afer recording SIZE bytes\n");
+                "   -s SIZE   --  stop tracing afer recording SIZE bytes\n"
+                "   -c        --  calibrate the CPU cycle counter offsets\n"
+                "\n");
         exit(1);
 }
 
@@ -105,11 +131,12 @@ static void shutdown(int sig)
                 fprintf(stderr, "disable_all: %m\n");
 }
 
-#define OPTSTR "s:"
+#define OPTSTR "s:c"
 
 int main(int argc, char** argv)
 {
         int opt;
+        int want_calibrate = 0;
 
         const char* trace_file;
 
@@ -120,6 +147,9 @@ int main(int argc, char** argv)
                         if (stop_after_bytes == 0)
                                 usage("invalid size (%s)", optarg);
                         break;
+                case 'c':
+                        want_calibrate = 1;
+                        break;
                 case ':':
                         usage("Argument missing.");
                         break;
@@ -142,6 +172,12 @@ int main(int argc, char** argv)
                 usage("could not open feathertrace device (%s): %m", trace_file);
                 return 1;
         }
+
+        if (want_calibrate && !calibrate_cycle_offsets(fd)) {
+                fprintf(stderr, "Calibrating %s failed: %m\n", *argv);
+                return 3;
+        }
+
         argc -= 1;
         argv += 1;
         signal(SIGINT, shutdown);