diff --git a/fs/procfs/fs_procfsproc.c b/fs/procfs/fs_procfsproc.c
index f82354326f..fd532db835 100644
--- a/fs/procfs/fs_procfsproc.c
+++ b/fs/procfs/fs_procfsproc.c
@@ -802,7 +802,7 @@ static ssize_t proc_critmon(FAR struct proc_file_s *procfile,
   linesize = procfs_snprintf(procfile->line, STATUS_LINELEN, "%lu.%09lu,",
                              (unsigned long)maxtime.tv_sec,
                              (unsigned long)maxtime.tv_nsec);
-  copysize = procfs_memcpy(procfile->line, linesize, buffer, buflen,
+  copysize = procfs_memcpy(procfile->line, linesize, buffer, remaining,
                            &offset);
 
   totalsize += copysize;
@@ -832,10 +832,43 @@ static ssize_t proc_critmon(FAR struct proc_file_s *procfile,
 
   /* Generate output for maximum time in a critical section */
 
+  linesize = procfs_snprintf(procfile->line, STATUS_LINELEN, "%lu.%09lu,",
+                             (unsigned long)maxtime.tv_sec,
+                             (unsigned long)maxtime.tv_nsec);
+  copysize = procfs_memcpy(procfile->line, linesize, buffer, remaining,
+                           &offset);
+
+  totalsize += copysize;
+  buffer    += copysize;
+  remaining -= copysize;
+
+  if (totalsize >= buflen)
+    {
+      return totalsize;
+    }
+
+  /* Convert and generate output for maximum time thread running */
+
+  if (tcb->run_max > 0)
+    {
+      up_critmon_convert(tcb->run_max, &maxtime);
+    }
+  else
+    {
+      maxtime.tv_sec = 0;
+      maxtime.tv_nsec = 0;
+    }
+
+  /* Reset the maximum */
+
+  tcb->run_max = 0;
+
+  /* Generate output for maximum time thread running */
+
   linesize = procfs_snprintf(procfile->line, STATUS_LINELEN, "%lu.%09lu\n",
                              (unsigned long)maxtime.tv_sec,
                              (unsigned long)maxtime.tv_nsec);
-  copysize = procfs_memcpy(procfile->line, linesize, buffer, buflen,
+  copysize = procfs_memcpy(procfile->line, linesize, buffer, remaining,
                            &offset);
 
   totalsize += copysize;
diff --git a/include/nuttx/sched.h b/include/nuttx/sched.h
index d54e04fd42..e5577bbd80 100644
--- a/include/nuttx/sched.h
+++ b/include/nuttx/sched.h
@@ -707,6 +707,8 @@ struct tcb_s
   uint32_t premp_max;                    /* Max time preemption disabled        */
   uint32_t crit_start;                   /* Time critical section entered       */
   uint32_t crit_max;                     /* Max time in critical section        */
+  uint32_t run_start;                    /* Time when thread begin run          */
+  uint32_t run_max;                      /* Max time thread run                 */
 #endif
 
   /* State save areas *******************************************************/
diff --git a/sched/sched/sched_critmonitor.c b/sched/sched/sched_critmonitor.c
index 55611c100e..97862b7ee5 100644
--- a/sched/sched/sched_critmonitor.c
+++ b/sched/sched/sched_critmonitor.c
@@ -208,10 +208,14 @@ void nxsched_critmon_csection(FAR struct tcb_s *tcb, bool state)
 
 void nxsched_resume_critmon(FAR struct tcb_s *tcb)
 {
-  uint32_t elapsed;
+  uint32_t current = up_critmon_gettime();
   int cpu = this_cpu();
+  uint32_t elapsed;
 
-  DEBUGASSERT(tcb->premp_start == 0 && tcb->crit_start == 0);
+  DEBUGASSERT(tcb->premp_start == 0 && tcb->crit_start == 0 &&
+              tcb->run_start == 0);
+
+  tcb->run_start = current;
 
   /* Did this task disable pre-emption? */
 
@@ -219,7 +223,7 @@ void nxsched_resume_critmon(FAR struct tcb_s *tcb)
     {
       /* Yes.. Save the start time */
 
-      tcb->premp_start = up_critmon_gettime();
+      tcb->premp_start = current;
       DEBUGASSERT(tcb->premp_start != 0);
 
       /* Zero means that the timer is not ready */
@@ -233,7 +237,7 @@ void nxsched_resume_critmon(FAR struct tcb_s *tcb)
     {
       /* Check for the global max elapsed time */
 
-      elapsed            = up_critmon_gettime() - g_premp_start[cpu];
+      elapsed            = current - g_premp_start[cpu];
       g_premp_start[cpu] = 0;
 
       if (elapsed > g_premp_max[cpu])
@@ -248,7 +252,7 @@ void nxsched_resume_critmon(FAR struct tcb_s *tcb)
     {
       /* Yes.. Save the start time */
 
-      tcb->crit_start = up_critmon_gettime();
+      tcb->crit_start = current;
       DEBUGASSERT(tcb->crit_start != 0);
 
       if (g_crit_start[cpu] == 0)
@@ -260,7 +264,7 @@ void nxsched_resume_critmon(FAR struct tcb_s *tcb)
     {
       /* Check for the global max elapsed time */
 
-      elapsed      = up_critmon_gettime() - g_crit_start[cpu];
+      elapsed      = current - g_crit_start[cpu];
       g_crit_start[cpu] = 0;
 
       if (elapsed > g_crit_max[cpu])
@@ -285,7 +289,14 @@ void nxsched_resume_critmon(FAR struct tcb_s *tcb)
 
 void nxsched_suspend_critmon(FAR struct tcb_s *tcb)
 {
-  uint32_t elapsed;
+  uint32_t current = up_critmon_gettime();
+  uint32_t elapsed = current - tcb->run_start;
+
+  tcb->run_start = 0;
+  if (elapsed > tcb->run_max)
+    {
+      tcb->run_max = elapsed;
+    }
 
   /* Did this task disable preemption? */
 
@@ -293,7 +304,7 @@ void nxsched_suspend_critmon(FAR struct tcb_s *tcb)
     {
       /* Possibly re-enabling.. Check for the max elapsed time */
 
-      elapsed = up_critmon_gettime() - tcb->premp_start;
+      elapsed = current - tcb->premp_start;
 
       tcb->premp_start = 0;
       if (elapsed > tcb->premp_max)
@@ -308,7 +319,7 @@ void nxsched_suspend_critmon(FAR struct tcb_s *tcb)
     {
       /* Possibly leaving .. Check for the max elapsed time */
 
-      elapsed = up_critmon_gettime() - tcb->crit_start;
+      elapsed = current - tcb->crit_start;
 
       tcb->crit_start = 0;
       if (elapsed > tcb->crit_max)