Print TSC timestamp during kerf exec

Signed-off-by: Cong Wang <cwang@multikernel.io>

Author: congwang-mk

pyproject.toml

@@ -19,6 +19,7 @@ pylibfdt = "^1.7.0"
 click = "^8.0.0"
 pyyaml = "^6.0"
 pyudev = "^0.24.0"
+rdtsc = "^0.2.1"
 
 [tool.poetry.group.dev.dependencies]
 pytest = "^7.0.0"

src/init/init.c

@@ -21,6 +21,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -29,7 +30,6 @@
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <termios.h>
-#include <time.h>
 #include <unistd.h>
 
 #define CMDLINE_PATH "/proc/cmdline"
@@ -63,22 +63,19 @@ static void log_error(const char *msg)
     log_msg(buf);
 }
 
-static void log_starting(void)
+static inline uint64_t rdtsc(void)
 {
-    struct timespec ts;
-    struct tm tm;
-    char buf[80];
+    uint32_t lo, hi;
+    asm volatile("rdtsc" : "=a"(lo), "=d"(hi));
+    return ((uint64_t)hi << 32) | lo;
+}
 
-    if (clock_gettime(CLOCK_REALTIME, &ts) < 0 ||
-        gmtime_r(&ts.tv_sec, &tm) == NULL) {
-        log_msg("starting");
-        return;
-    }
+static void log_starting(void)
+{
+    char buf[64];
+    uint64_t tsc = rdtsc();
 
-    snprintf(buf, sizeof(buf), "starting at %04d-%02d-%02d %02d:%02d:%02d.%03ld UTC",
-             tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
-             tm.tm_hour, tm.tm_min, tm.tm_sec,
-             ts.tv_nsec / 1000000);
+    snprintf(buf, sizeof(buf), "starting at TSC %lu", tsc);
     log_msg(buf);
 }
 

src/kerf/exec/main.py

@@ -24,6 +24,7 @@
 from typing import Optional
 
 import click
+import rdtsc
 
 from ..models import InstanceState
 from ..utils import get_instance_id_from_name
@@ -38,7 +39,6 @@
 SYS_REBOOT_ARM = 88
 SYS_REBOOT_X86 = 88
 
-
 def get_reboot_syscall():
     """Get the reboot syscall number for current architecture."""
     arch = platform.machine().lower()
@@ -211,7 +211,8 @@ def exec_cmd(name: Optional[str], id: Optional[int], attach_console: bool, verbo
             click.echo(f"✓ Kernel image found for instance '{instance_name}'")
             click.echo(f"Instance ID to boot: {instance_id}")
             click.echo(f"Using reboot syscall with command: 0x{LINUX_REBOOT_CMD_MULTIKERNEL:x}")
-            click.echo("Calling reboot syscall...")
+            tsc = rdtsc.get_cycles()
+            click.echo(f"Calling reboot syscall at TSC {tsc}")
         else:
             click.echo(f"Booting instance '{instance_name}' (ID: {instance_id})...")