diff --git a/include/common/time.h b/include/common/time.h
index d4446dc..a1664b4 100644
--- a/include/common/time.h
+++ b/include/common/time.h
@@ -63,6 +63,8 @@
 extern struct timeval start_date;       /* the process's start date */
 extern THREAD_LOCAL struct timeval before_poll;      /* system date before calling poll() */
 extern THREAD_LOCAL struct timeval after_poll;       /* system date after leaving poll() */
+extern THREAD_LOCAL uint64_t prev_cpu_time;          /* previous per thread CPU time */
+extern THREAD_LOCAL uint64_t prev_mono_time;         /* previous system wide monotonic time */
 
 
 /**** exported functions *************************************************/
@@ -83,6 +85,11 @@
  */
 REGPRM2 int tv_ms_cmp2(const struct timeval *tv1, const struct timeval *tv2);
 
+/* Updates the current thread's statistics about stolen CPU time. The unit for
+ * <stolen> is half-milliseconds.
+ */
+REGPRM1 void report_stolen_time(uint64_t stolen);
+
 /**** general purpose functions and macros *******************************/
 
 
@@ -574,6 +581,26 @@
  */
 static inline void tv_entering_poll()
 {
+	uint64_t new_mono_time;
+	uint64_t new_cpu_time;
+	int64_t stolen;
+
+	new_cpu_time   = now_cpu_time();
+	new_mono_time  = now_mono_time();
+
+	if (prev_cpu_time && prev_mono_time) {
+		new_cpu_time  -= prev_cpu_time;
+		new_mono_time -= prev_mono_time;
+		stolen = new_mono_time - new_cpu_time;
+		if (stolen >= 500000) {
+			stolen /= 500000;
+			/* more than half a millisecond difference might
+			 * indicate an undesired preemption.
+			 */
+			report_stolen_time(stolen);
+		}
+	}
+
 	gettimeofday(&before_poll, NULL);
 }
 
@@ -586,6 +613,8 @@
 {
 	tv_update_date(timeout, interrupted);
 	measure_idle();
+	prev_cpu_time  = now_cpu_time();
+	prev_mono_time = now_mono_time();
 }
 
 #endif /* _COMMON_TIME_H */
diff --git a/include/types/global.h b/include/types/global.h
index 616e8d3..5262867 100644
--- a/include/types/global.h
+++ b/include/types/global.h
@@ -195,6 +195,9 @@
 	unsigned int stream;       // calls to process_stream()
 	unsigned int empty_rq;     // calls to process_runnable_tasks() with nothing for the thread
 	unsigned int long_rq;      // process_runnable_tasks() left with tasks in the run queue
+	unsigned int cpust_total;  // sum of half-ms stolen per thread
+	struct freq_ctr cpust_1s;  // avg amount of half-ms stolen over last second
+	struct freq_ctr_period cpust_15s; // avg amount of half-ms stolen over last 15s
 	char __pad[0]; // unused except to check remaining room
 	char __end[0] __attribute__((aligned(64))); // align size to 64.
 };
diff --git a/src/cli.c b/src/cli.c
index ed17aac..07dce53 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -972,6 +972,9 @@
 	chunk_appendf(&trash, "\nstream:");       for (thr = 0; thr < global.nbthread; thr++) chunk_appendf(&trash, " %u", activity[thr].stream);
 	chunk_appendf(&trash, "\nempty_rq:");     for (thr = 0; thr < global.nbthread; thr++) chunk_appendf(&trash, " %u", activity[thr].empty_rq);
 	chunk_appendf(&trash, "\nlong_rq:");      for (thr = 0; thr < global.nbthread; thr++) chunk_appendf(&trash, " %u", activity[thr].long_rq);
+	chunk_appendf(&trash, "\ncpust_tot:");    for (thr = 0; thr < global.nbthread; thr++) chunk_appendf(&trash, " %u", activity[thr].cpust_total/2);
+	chunk_appendf(&trash, "\ncpust_1s:");     for (thr = 0; thr < global.nbthread; thr++) chunk_appendf(&trash, " %u", read_freq_ctr(&activity[thr].cpust_1s)/2);
+	chunk_appendf(&trash, "\ncpust_15s:");    for (thr = 0; thr < global.nbthread; thr++) chunk_appendf(&trash, " %u", read_freq_ctr_period(&activity[thr].cpust_15s, 15000)/2);
 
 	chunk_appendf(&trash, "\n");
 
diff --git a/src/time.c b/src/time.c
index 0de6962..b404b25 100644
--- a/src/time.c
+++ b/src/time.c
@@ -10,12 +10,16 @@
  *
  */
 
+#include <stdint.h>
+#include <unistd.h>
 #include <sys/time.h>
 
 #include <common/config.h>
 #include <common/standard.h>
 #include <common/time.h>
 #include <common/hathreads.h>
+#include <types/global.h>
+#include <proto/freq_ctr.h>
 
 THREAD_LOCAL unsigned int   ms_left_scaled;  /* milliseconds left for current second (0..2^32-1) */
 THREAD_LOCAL unsigned int   now_ms;          /* internal date in milliseconds (may wrap) */
@@ -27,6 +31,8 @@
 struct timeval start_date;      /* the process's start date */
 THREAD_LOCAL struct timeval before_poll;     /* system date before calling poll() */
 THREAD_LOCAL struct timeval after_poll;      /* system date after leaving poll() */
+THREAD_LOCAL uint64_t prev_cpu_time = 0;     /* previous per thread CPU time */
+THREAD_LOCAL uint64_t prev_mono_time = 0;    /* previous system wide monotonic time */
 
 static THREAD_LOCAL struct timeval tv_offset;  /* per-thread time ofsset relative to global time */
 volatile unsigned long long global_now;        /* common date between all threads (32:32) */
@@ -258,6 +264,16 @@
 	return;
 }
 
+/* Updates the current thread's statistics about stolen CPU time. The unit for
+ * <stolen> is half-milliseconds.
+ */
+REGPRM1 void report_stolen_time(uint64_t stolen)
+{
+	activity[tid].cpust_total += stolen;
+	update_freq_ctr(&activity[tid].cpust_1s, stolen);
+	update_freq_ctr_period(&activity[tid].cpust_15s, 15000, stolen);
+}
+
 /*
  * Local variables:
  *  c-indent-level: 8