run without root permission

perf-collect.py

@@ -161,6 +161,7 @@ def supports_psi():
 def tma_supported():
     perf_out = ""
     try:
+        # run perf stat briefly to determine if these two events are supported
         perf = subprocess.Popen(
             shlex.split(
                 "perf stat -a -e '{cpu/event=0x00,umask=0x04,period=10000003,name='TOPDOWN.SLOTS'/,cpu/event=0x00,umask=0x81,period=10000003,name='PERF_METRICS.BAD_SPECULATION'/}' sleep .1"
@@ -170,9 +171,11 @@ def tma_supported():
         )
         perf_out = perf.communicate()[0].decode()
     except subprocess.CalledProcessError:
+        logging.info("perf stat exited with error while checking for TMA support")
         return False
 
     try:
+        # create a dictionary of perf events and their counts from perf stat output
         events = {
             a.split()[1]: int(a.split()[0].replace(",", ""))
             for a in filter(
@@ -181,10 +184,17 @@ def tma_supported():
             )
         }
     except Exception:
+        logging.info("error parsing perf stat output while checking for TMA support")
         return False
 
     # This is a perf artifact of no vPMU support
     if events["TOPDOWN.SLOTS"] == events["PERF_METRICS.BAD_SPECULATION"]:
+        logging.info("TOPDOWN.SLOTS and PERF_METRICS.BAD_SPECULATION counts are equal")
+        return False
+
+    # A zero value on either of these metrics is an indication that the TMA events are not supported
+    if events["TOPDOWN.SLOTS"] == 0 or events["PERF_METRICS.BAD_SPECULATION"] == 0:
+        logging.info("TOPDOWN.SLOTS or PERF_METRICS.BAD_SPECULATION count is zero")
         return False
 
     return True
@@ -295,7 +305,9 @@ def validate_file(fname):
         sys.exit()
 
     if os.geteuid() != 0:
-        crash("Must run PerfSpect as root, please re-run")
+        logging.warning(
+            "PerfSpect requires elevated permissions to run. User is not root. Proceeding anyway..."
+        )
 
     # disable nmi watchdog before collecting perf
     nmi_watchdog = perf_helpers.disable_nmi_watchdog()

src/perf_helpers.py

@@ -145,7 +145,9 @@ def disable_nmi_watchdog():
         proc_output = subprocess.check_output(["cat", "/proc/sys/kernel/nmi_watchdog"])
         nmi_watchdog_status = int(proc_output.decode().strip())
         if nmi_watchdog_status == 1:
-            proc_output = subprocess.check_output(["sysctl", "kernel.nmi_watchdog=0"])
+            proc_output = subprocess.check_output(
+                ["sysctl", "kernel.nmi_watchdog=0"], stderr=subprocess.STDOUT
+            )
             new_watchdog_status = int(
                 proc_output.decode().strip().replace("kernel.nmi_watchdog = ", "")
             )
@@ -158,7 +160,7 @@ def disable_nmi_watchdog():
             logging.info("nmi_watchdog already disabled. No change needed.")
         return nmi_watchdog_status
     except (ValueError, FileNotFoundError, subprocess.CalledProcessError) as e:
-        crash(f"Failed to disable nmi_watchdog: {e}")
+        logging.warning(f"Failed to disable nmi_watchdog: {e}")
 
 
 # enable nmi watchdog
@@ -183,15 +185,19 @@ def set_perf_event_mux_interval(reset, interval_ms, mux_interval):
         if os.path.isdir(dirpath):
             muxfile = os.path.join(dirpath, "perf_event_mux_interval_ms")
             if os.path.isfile(muxfile):
-                with open(muxfile, "w") as f_mux:
-                    val = 0
-                    if reset:
-                        val = int(mux_interval[f])
-                    else:
-                        if int(mux_interval[f]):
-                            val = int(interval_ms)
-                    if val:
-                        f_mux.write(str(val))
+                try:
+                    with open(muxfile, "w") as f_mux:
+                        val = 0
+                        if reset:
+                            val = int(mux_interval[f])
+                        else:
+                            if int(mux_interval[f]):
+                                val = int(interval_ms)
+                        if val:
+                            f_mux.write(str(val))
+                except OSError as e:
+                    logging.warning(f"Failed to write mux interval: {e}")
+                    break
 
 
 # get linux kernel version

src/prepare_perf_events.py

@@ -63,8 +63,8 @@ def is_cpu_event(line):
     if (
         (len(tmp_list) == 1 or tmp_list[0] == "cpu" or tmp_list[0].startswith("cstate"))
         and "OCR." not in line
-        and "uops_retired.ms" not in line
-        and "int_misc.unknown_branch_cycles" not in line
+        and "uops_retired.ms" not in line.lower()
+        and "int_misc.unknown_branch_cycles" not in line.lower()
         and "power/" not in line
     ):
         return True