Make sure we have the same number of migrations and preemptions.

This skips unneeded samples once the desired number of migrations has been observed.

1 files changed, 28 insertions, 12 deletions

diff --git a/bin/cache_cost.c b/bin/cache_cost.c
index a33c1a0..808ca33 100644
--- a/bin/cache_cost.c
+++ b/bin/cache_cost.c
@@ -138,7 +138,9 @@ static void do_random_experiment(FILE* outfile,
                                  int sleep_min, int sleep_max,
                                  int write_cycle, int sample_count)
 {
-        int last_cpu, next_cpu, delay;
+        int last_cpu, next_cpu, delay, show = 1;
+        unsigned long preempt_counter = 0;
+        unsigned long migration_counter = 0;
         unsigned long counter = 1;
 
         cycles_t start, stop;
@@ -155,10 +157,17 @@ static void do_random_experiment(FILE* outfile,
 #if defined(__i386__) || defined(__x86_64__)
         iopl(3);
 #endif
-        while (!sample_count || sample_count >= counter) {
+        while (!sample_count ||
+               sample_count >= preempt_counter ||
+               sample_count >= migration_counter) {
+
                 delay = sleep_min + random() % (sleep_max - sleep_min + 1);
                 next_cpu = random() % num_cpus;
 
+                if (sample_count)
+                        show = (next_cpu == last_cpu && sample_count >= preempt_counter) ||
+                                (next_cpu != last_cpu && sample_count >= migration_counter);
+
                 mem = allocate(wss);
 
 #if defined(__i386__) || defined(__x86_64__)
@@ -200,18 +209,25 @@ static void do_random_experiment(FILE* outfile,
 #endif
                 after_resume = stop - start;
 
+
                 /* run, write ratio, wss, delay, from, to, cold, hot1, hot2,
                  * hot3, after_resume */
-                fprintf(outfile,
-                        "%6ld, %3d, %6d, %6d, %3d, %3d, "
-                        "%" CYCLES_FMT ", "
-                        "%" CYCLES_FMT ", "
-                        "%" CYCLES_FMT ", "
-                        "%" CYCLES_FMT ", "
-                        "%" CYCLES_FMT "\n",
-                        counter++, write_cycle,
-                        wss, delay, last_cpu, next_cpu, cold, hot1, hot2, hot3,
-                        after_resume);
+                if (show)
+                        fprintf(outfile,
+                                "%6ld, %3d, %6d, %6d, %3d, %3d, "
+                                "%" CYCLES_FMT ", "
+                                "%" CYCLES_FMT ", "
+                                "%" CYCLES_FMT ", "
+                                "%" CYCLES_FMT ", "
+                                "%" CYCLES_FMT "\n",
+                                counter++, write_cycle,
+                                wss, delay, last_cpu, next_cpu, cold,
+                                hot1, hot2, hot3,
+                                after_resume);
+                if (next_cpu == last_cpu)
+                        preempt_counter++;
+                else
+                        migration_counter++;
                 last_cpu = next_cpu;
                 deallocate(mem);
         }