latency: skip RT-privilege warning on non-RT kernels

Only warn under PREEMPT_RT or RTAI; on a non-RT kernel the privileges
do not matter, so the check would be noise.

Author: grandixximo

scripts/latency-histogram

@@ -115,6 +115,11 @@ proc check_rt_privileges {} {
   # Without 'sudo make setuid' (or 'sudo make setcap') rtapi_app runs
   # unprivileged: realtime threads get no SCHED_FIFO and no locked memory, so
   # the latency readings are wildly inflated.  Warn rather than mislead.
+  # Only meaningful on an RT-capable kernel; stay quiet on non-RT (e.g. dev).
+  set rt 0
+  if {![catch {exec uname -v} kv] && [string match *PREEMPT_RT* $kv]} {set rt 1}
+  if {[string first rtai [string tolower $::tcl_platform(osVersion)]] >= 0} {set rt 1}
+  if {!$rt} return
   if {![catch {exec id -u} uid] && $uid == 0} return ;# root has every privilege
   if {[catch {which_exe rtapi_app} rtapi]} return ;# cannot locate, stay quiet
   if {![catch {file attributes $rtapi -permissions} mode] && ($mode & 04000)} return ;# setuid root

scripts/latency-test

@@ -20,6 +20,11 @@ icalc() { awk "BEGIN { printf \"%.0f\n\", ($1); }" < /dev/null; }
 # unprivileged: realtime threads get no SCHED_FIFO and no locked memory, so the
 # latency readings are wildly inflated.  Warn rather than mislead.
 check_rt_privileges () {
+    # only meaningful on an RT-capable kernel; stay quiet on non-RT (e.g. dev)
+    case "$(uname -v) $(uname -r)" in
+        *PREEMPT_RT*|*rtai*) ;;
+        *) return 0 ;;
+    esac
     [ "$(id -u)" = 0 ] && return 0          # root has every privilege
     rtapi_app=$(command -v rtapi_app) || return 0
     [ -n "$rtapi_app" ] || return 0