fix bug in overshoot_fudge computation; reduce number of knobs

git-svn-id: svn+ssh://svn.corp.yahoo.com/yahoo/yrl/labs/pnuts/code/logstore@860 8dad8b1f-cf64-0410-95b6-bcf113ffbcfe

mergeManager.cpp

@@ -48,15 +48,13 @@ void mergeManager::set_c0_size(int64_t size) {
   c0->target_size = size;
 }
 
-static const int UPDATE_PROGRESS_DELTA = 1 * 1024 * 1024;
-
 void mergeManager::update_progress(mergeStats * s, int delta) {
   s->delta += delta;
-  if((!delta) || s->delta > UPDATE_PROGRESS_DELTA) { //512 * 1024) {
+  if((!delta) || s->delta > UPDATE_PROGRESS_DELTA) {
     if(delta) {
       rwlc_writelock(ltable->header_mut);
       s->delta = 0;
-      s->need_tick = true;
+      if(!s->need_tick) { s->need_tick = 1; }
     }
     if(s->merge_level != 0) {
       if(s->active) {
@@ -69,7 +67,7 @@ void mergeManager::update_progress(mergeStats * s, int delta) {
       if(s->mergeable_size) {
         s->out_progress = ((double)s->current_size) / (double)s->target_size;
       } else {
-        s->out_progress = 0;
+        s->out_progress = 0.0;
       }
     }
     s->current_size = s->base_size + s->bytes_out - s->bytes_in_large;
@@ -116,13 +114,12 @@ void mergeManager::update_progress(mergeStats * s, int delta) {
  * bytes_consumed_by_merger = sum(bytes_in_small_delta)
  */
 void mergeManager::tick(mergeStats * s, bool block, bool force) {
-#define PRINT_SKIP 1000
-
+#define PRINT_SKIP 100
   if(force || s->need_tick) {
 
     if(block) {
       rwlc_writelock(ltable->header_mut);
-      s->need_tick = false;
+
       while(sleeping[s->merge_level]) {
         rwlc_cond_wait(&throttle_wokeup_cond, ltable->header_mut);
       }
@@ -130,8 +127,9 @@ void mergeManager::tick(mergeStats * s, bool block, bool force) {
       int64_t overshoot = 0;
       int64_t raw_overshoot = 0;
 //      int64_t overshoot_fudge = (int64_t)((s->out_progress-0.5) * 18.0 * 1024.0 * 1024.0);
-      double skew = 0.1; // should be between 0 and 0.5.  0 means that there is no 'catch up' after merge commit
-      int64_t overshoot_fudge = (int64_t)((s->out_progress-skew) * (6 / (1.0-skew)) * 1024.0 * 1024.0);  // should be some function of R, delta interval, and force interval.
+//      double skew = 0.5; // should be between 0 and 0.5.  0 means that there is no 'catch up' after merge commit
+      int64_t overshoot_fudge = UPDATE_PROGRESS_DELTA + (int64_t)(s->out_progress * ((double)FORCE_INTERVAL)); //+ (int64_t)((s->out_progress-skew) * (0.0 / (1.0-skew)) * 1024.0 * 1024.0);  // should be some function of R, delta interval, and force interval. // xxx divide FORCE_INTERVAL by R?
+      overshoot_fudge *= 2;
       int spin = 0;
       double total_sleep = 0.0;
       do{
@@ -161,7 +159,7 @@ void mergeManager::tick(mergeStats * s, bool block, bool force) {
         } else {
           s->print_skipped++;
         }
-        if(overshoot > 0 && (raw_overshoot > 0 || total_sleep < 1)) {
+        if(overshoot > 0 && (raw_overshoot > 0 || total_sleep < 0.01)) {
           // throttle
           // it took "elapsed" seconds to process "tick_length_bytes" mb
           double sleeptime = 2.0 * (double)overshoot / bps;
@@ -170,7 +168,7 @@ void mergeManager::tick(mergeStats * s, bool block, bool force) {
 
           double max_c0_sleep = 0.1;
           double min_c0_sleep = 0.05;
-          double max_c1_sleep = 0.1;
+          double max_c1_sleep = 0.5;
           double min_c1_sleep = 0.1;
           double max_sleep = s->merge_level == 0 ? max_c0_sleep : max_c1_sleep;
           double min_sleep = s->merge_level == 0 ? min_c0_sleep : min_c1_sleep;
@@ -199,7 +197,12 @@ void mergeManager::tick(mergeStats * s, bool block, bool force) {
           if(s->merge_level == 0) { update_progress(c1, 0); }
           if(s->merge_level == 1) { update_progress(c2, 0); }
         } else {
-          if(overshoot > 0) { s->need_tick = true; }
+          if(overshoot > 0) {
+            s->need_tick ++;
+            if(s->need_tick > 100) { printf("need tick %d\n", s->need_tick); }
+          } else {
+            s->need_tick = 0;
+          }
           break;
         }
       } while(1);

mergeManager.h

@@ -21,6 +21,8 @@ class mergeStats;
 
 class mergeManager {
 public:
+  static const int UPDATE_PROGRESS_DELTA = 1024 * 1024;
+  static const int FORCE_INTERVAL = 5 * 1024 * 1024;
   static double tv_to_double(struct timeval * tv) {
     return (double)tv->tv_sec + ((double)tv->tv_usec)/1000000.0;
   }

mergeStats.h

@@ -39,7 +39,7 @@ class mergeStats {
       num_tuples_in_large(0),
       just_handed_off(false),
       delta(0),
-      need_tick(false),
+      need_tick(0),
       in_progress(0),
       out_progress(0),
       lifetime_elapsed(0),
@@ -133,7 +133,7 @@ class mergeStats {
     bool just_handed_off;
 
     int delta;
-    bool need_tick;
+    int need_tick;
     double in_progress;
     double out_progress;
 

merger.cpp

@@ -390,10 +390,8 @@ void *diskMergeThread(void*arg)
     return 0;
 }
 
-#define FORCE_INTERVAL (5 * 1024 * 1024) // XXX do not hardcode FORCE_INTERVAL
-
 static void periodically_force(int xid, int *i, diskTreeComponent * forceMe, stasis_log_t * log) {
-  if(*i > FORCE_INTERVAL) {
+  if(*i > mergeManager::FORCE_INTERVAL) {
     if(forceMe) forceMe->force(xid);
     log->force_tail(log, LOG_FORCE_WAL);
     *i = 0;