Merge remote-tracking branch 'github/master'

Conflicts:
	bin/rtspin.c

Resolve option clash by moving the calibration loop to -a0.

2 files changed, 112 insertions, 30 deletions

diff --git a/bin/rtspin.c b/bin/rtspin.c
index 68f721d..fb7f13f 100644
--- a/bin/rtspin.c
+++ b/bin/rtspin.c
@@ -19,8 +19,9 @@ const char *usage_msg =
         "Usage: (1) rtspin OPTIONS WCET PERIOD DURATION\n"
         "       (2) rtspin -S [INPUT] WCET PERIOD DURATION\n"
         "       (3) rtspin OPTIONS -C FILE:COLUMN WCET PERIOD [DURATION]\n"
-        "       (4) rtspin -l\n"
+        "       (4) rtspin -l [-a CYCLES]\n"
         "       (5) rtspin -B -m FOOTPRINT\n"
+        "       (6) rtspin -a 0\n"
         "\n"
         "Modes: (1) run as periodic task with given WCET and PERIOD\n"
         "       (2) run as sporadic task with given WCET and PERIOD,\n"
@@ -31,12 +32,15 @@ const char *usage_msg =
         "       (4) Run calibration loop (how accurately are target\n"
         "           runtimes met?)\n"
         "       (5) Run background, non-real-time cache-thrashing loop.\n"
+        "       (6) Run 1 ms workload calibration (estimate cycles for 1ms, 10ms, 100ms workload)\n"
         "\n"
         "Required arguments:\n"
         "    WCET, PERIOD      reservation parameters (in ms)\n"
         "    DURATION          terminate the task after DURATION seconds\n"
         "\n"
         "Options:\n"
+        "    -a CYCLES         number of cycles for 1ms of workload loop chosen after calibration;\n "
+        "                      pass '0' to run the calibration loop\n"
         "    -B                run non-real-time background loop\n"
         "    -c be|srt|hrt     task class (best-effort, soft real-time, hard real-time)\n"
         "    -d DEADLINE       relative deadline, equal to the period by default (in ms)\n"
@@ -106,18 +110,23 @@ static int nr_of_pages = 0;
 static int page_size;
 static void *base = NULL;
 
-static int loop_once(void)
+static int cycles_ms = 0;
+
+static noinline int loop(int count)
 {
         int i, j = 0;
         /* touch some numbers and do some math */
-        for (i = 0; i < NUMS; i++) {
-                j += num[i]++;
-                if (j > num[i])
-                        num[i] = (j / 2) + 1;
+        for (i = 0; i < count; i++) {
+                int index = i % NUMS;
+                j += num[index]++;
+                if (j > num[index])
+                        num[index] = (j / 2) + 1;
         }
         return j;
 }
 
+#define loop_once() loop(NUMS)
+
 static int loop_once_with_mem(void)
 {
         int i, j = 0;
@@ -143,30 +152,35 @@ static int loop_once_with_mem(void)
 
 static int loop_for(double exec_time, double emergency_exit)
 {
-        double last_loop = 0, loop_start;
         int tmp = 0;
 
-        double start = cputime();
-        double now = cputime();
+        if (cycles_ms) {
+                double count = cycles_ms * exec_time * 1000;
+                tmp += loop(count);
+        } else {
+                double last_loop = 0, loop_start;
+                double start = cputime();
+                double now = cputime();
 
-        while (now + last_loop < start + exec_time) {
-                loop_start = now;
-                if (nr_of_pages)
-                        tmp += loop_once_with_mem();
-                else
-                        tmp += loop_once();
-                now = cputime();
-                last_loop = now - loop_start;
-                if (emergency_exit && wctime() > emergency_exit) {
-                        /* Oops --- this should only be possible if the
-                         * execution time tracking is broken in the LITMUS^RT
-                         * kernel or the user specified infeasible parameters.
-                         */
-                        fprintf(stderr, "!!! rtspin/%d emergency exit!\n",
-                                getpid());
-                        fprintf(stderr, "Reached experiment timeout while "
-                                "spinning.\n");
-                        break;
+                while (now + last_loop < start + exec_time) {
+                        loop_start = now;
+                        if (nr_of_pages)
+                                tmp += loop_once_with_mem();
+                        else
+                                tmp += loop_once();
+                        now = cputime();
+                        last_loop = now - loop_start;
+                        if (emergency_exit && wctime() > emergency_exit) {
+                                /* Oops --- this should only be possible if the
+                                 * execution time tracking is broken in the LITMUS^RT
+                                 * kernel or the user specified infeasible parameters.
+                                 */
+                                fprintf(stderr, "!!! rtspin/%d emergency exit!\n",
+                                        getpid());
+                                fprintf(stderr, "Reached experiment timeout while "
+                                        "spinning.\n");
+                                break;
+                        }
                 }
         }
 
@@ -180,9 +194,9 @@ static void debug_delay_loop(void)
 
         while (1) {
                 for (delay = 0.5; delay > 0.01; delay -= 0.01) {
-                        start = wctime();
+                        start = cputime();
                         loop_for(delay, 0);
-                        end = wctime();
+                        end = cputime();
                         printf("%6.4fs: looped for %10.8fs, delta=%11.8fs, error=%7.4f%%\n",
                                delay,
                                end - start,
@@ -194,6 +208,51 @@ static void debug_delay_loop(void)
 
 static char input_buf[4096] = "<no input>";
 
+static int calibrate_ms(int ms)
+{
+        int right = NUMS;
+        int left = 0;
+        int middle;
+
+        double start;
+        double now;
+        double dms = 0.001 * ms;
+
+        /*look for initial loop count values for binary search*/
+        for (;;)
+        {
+                printf("Probe %d loops for %d ms:\n", right, ms);
+                start = wctime();
+                loop(right);
+                now = wctime();
+                if ((now - start) >= dms)
+                        break;
+                left = right;
+                right += right;
+        }
+
+        middle = (left + right) / 2;
+
+        /*binary search for a loop count value for expected calibration time*/
+        while (left < middle)
+        {
+                start = wctime();
+                loop(middle);
+                now = wctime();
+
+                printf("%d loops elapsed in %4.20f s\n", middle, now - start);
+
+                if ((now - start) < dms)
+                        left = middle;
+                else if ((now - start) == dms)
+                        return middle;
+                else
+                        right = middle;
+                middle = (left + right) / 2;
+        }
+        return middle;
+}
+
 static int wait_for_input(int event_fd)
 {
         /* We do a blocking read, accepting up to 4KiB of data.
@@ -277,7 +336,7 @@ static lt_t choose_inter_arrival_time_ns(
         return ms2ns(iat_ms);
 }
 
-#define OPTSTR "p:c:wlveo:s:m:q:r:X:L:Q:iRu:U:Bhd:C:S::O::TD:E:A:"
+#define OPTSTR "p:c:wlveo:s:m:q:r:X:L:Q:iRu:U:Bhd:C:S::O::TD:E:A:a:"
 
 int main(int argc, char** argv)
 {
@@ -298,6 +357,7 @@ int main(int argc, char** argv)
         int opt;
         int wait = 0;
         int test_loop = 0;
+        int caliber_ms = 0;
         int background_loop = 0;
 
         int cost_column = 1;
@@ -480,6 +540,11 @@ int main(int argc, char** argv)
                         verbose = 1;
                         report_interrupts = 1;
                         break;
+                case 'a':
+                        cycles_ms = want_non_negative_int(optarg, "-a");
+                        if (!cycles_ms)
+                                caliber_ms = 1;
+                        break;
                 case ':':
                         usage("Argument missing.");
                         break;
@@ -513,10 +578,21 @@ int main(int argc, char** argv)
         srand(getpid());
 
         if (test_loop) {
+                if (cycles_ms > 0)
+                        printf("Evaluating loop with %d cycles:\n", cycles_ms);
+
                 debug_delay_loop();
                 return 0;
         }
 
+        if (caliber_ms) {
+                printf("In 1 ms %d loops.\n", calibrate_ms(1));
+                printf("In 10 ms %d loops.\n", calibrate_ms(10));
+                printf("In 100 ms %d loops.\n", calibrate_ms(100));
+                printf("In 1 s %d loops.\n", calibrate_ms(1000));
+                return 0;
+        }
+
         if (background_loop) {
                 while (1) {
                         if (nr_of_pages)
diff --git a/include/common.h b/include/common.h
index b77ae67..7c33c94 100644
--- a/include/common.h
+++ b/include/common.h
@@ -6,6 +6,12 @@
 #ifndef COMMON_H
 #define COMMON_H
 
+#if defined(__GNUC__)
+#define noinline      __attribute__((__noinline__))
+#else
+#define noinline
+#endif
+
 /**
  * End the current task with a message
  * @param msg Message to output before bailing