osd: randomize deep scrubbing

src/common/config_opts.h

@@ -684,6 +684,7 @@ OPTION(osd_scrub_sleep, OPT_FLOAT, 0)   // sleep between [deep]scrub ops
 OPTION(osd_scrub_auto_repair, OPT_BOOL, false)   // whether auto-repair inconsistencies upon deep-scrubbing
 OPTION(osd_scrub_auto_repair_num_errors, OPT_U32, 5)   // only auto-repair when number of errors is below this threshold
 OPTION(osd_deep_scrub_interval, OPT_FLOAT, 60*60*24*7) // once a week
+OPTION(osd_deep_scrub_randomize_ratio, OPT_FLOAT, 0.15) // scrubs will randomly become deep scrubs at this rate (0.15 -> 15% of scrubs are deep)
 OPTION(osd_deep_scrub_stride, OPT_INT, 524288)
 OPTION(osd_deep_scrub_update_digest_min_age, OPT_INT, 2*60*60)   // objects must be this old (seconds) before we update the whole-object digest on scrub
 OPTION(osd_scan_list_ping_tp_interval, OPT_U64, 100)

src/osd/OSD.cc

@@ -1809,6 +1809,15 @@ int OSD::init()
 
   dout(2) << "boot" << dendl;
 
+  // initialize the daily loadavg with current 15min loadavg
+  double loadavgs[3];
+  if (getloadavg(loadavgs, 3) == 3) {
+    daily_loadavg = loadavgs[2];
+  } else {
+    derr << "OSD::init() : couldn't read loadavgs\n" << dendl;
+    daily_loadavg = 1.0;
+  }
+
   // read superblock
   r = read_superblock();
   if (r < 0) {
@@ -3862,8 +3871,12 @@ void OSD::heartbeat()
 
   // get CPU load avg
   double loadavgs[1];
-  if (getloadavg(loadavgs, 1) == 1)
+  int n_samples = 86400 / cct->_conf->osd_heartbeat_interval;
+  if (getloadavg(loadavgs, 1) == 1) {
     logger->set(l_osd_loadavg, 100 * loadavgs[0]);
+    daily_loadavg = (daily_loadavg * (n_samples - 1) + loadavgs[0]) / n_samples;
+    dout(30) << "heartbeat: daily_loadavg " << daily_loadavg << dendl;
+  }
 
   dout(30) << "heartbeat checking stats" << dendl;
 
@@ -6065,23 +6078,35 @@ bool OSD::scrub_time_permit(utime_t now)
 
 bool OSD::scrub_load_below_threshold()
 {
-  double loadavgs[1];
-  if (getloadavg(loadavgs, 1) != 1) {
+  double loadavgs[3];
+  if (getloadavg(loadavgs, 3) != 3) {
     dout(10) << __func__ << " couldn't read loadavgs\n" << dendl;
     return false;
   }
 
-  if (loadavgs[0] >= cct->_conf->osd_scrub_load_threshold) {
-    dout(20) << __func__ << " loadavg " << loadavgs[0]
-	     << " >= max " << cct->_conf->osd_scrub_load_threshold
-	     << " = no, load too high" << dendl;
-    return false;
-  } else {
+  // allow scrub if below configured threshold
+  if (loadavgs[0] < cct->_conf->osd_scrub_load_threshold) {
     dout(20) << __func__ << " loadavg " << loadavgs[0]
 	     << " < max " << cct->_conf->osd_scrub_load_threshold
 	     << " = yes" << dendl;
     return true;
   }
+
+  // allow scrub if below daily avg and currently decreasing
+  if (loadavgs[0] < daily_loadavg && loadavgs[0] < loadavgs[2]) {
+    dout(20) << __func__ << " loadavg " << loadavgs[0]
+	     << " < daily_loadavg " << daily_loadavg
+	     << " and < 15m avg " << loadavgs[2]
+	     << " = yes" << dendl;
+    return true;
+  }
+
+  dout(20) << __func__ << " loadavg " << loadavgs[0]
+	   << " >= max " << cct->_conf->osd_scrub_load_threshold
+	   << " and ( >= daily_loadavg " << daily_loadavg
+	   << " or >= 15m avg " << loadavgs[2]
+	   << ") = no" << dendl;
+  return false;
 }
 
 void OSD::sched_scrub()

src/osd/OSD.h

@@ -1505,6 +1505,7 @@ class OSD : public Dispatcher,
   Messenger *hb_front_server_messenger;
   Messenger *hb_back_server_messenger;
   utime_t last_heartbeat_resample;   ///< last time we chose random peers in waiting-for-healthy state
+  double daily_loadavg;
 
   void _add_heartbeat_peer(int p);
   void _remove_heartbeat_peer(int p);

src/osd/PG.cc

@@ -3246,6 +3246,11 @@ bool PG::sched_scrub()
   bool time_for_deep = (ceph_clock_now(cct) >=
     info.history.last_deep_scrub_stamp + cct->_conf->osd_deep_scrub_interval);
 
+  bool deep_coin_flip = (rand() % 100) < cct->_conf->osd_deep_scrub_randomize_ratio * 100;
+  dout(20) << __func__ << ": time_for_deep=" << time_for_deep << " deep_coin_flip=" << deep_coin_flip << dendl;
+
+  time_for_deep = (time_for_deep || deep_coin_flip);
+
   //NODEEP_SCRUB so ignore time initiated deep-scrub
   if (osd->osd->get_osdmap()->test_flag(CEPH_OSDMAP_NODEEP_SCRUB) ||
       pool.info.has_flag(pg_pool_t::FLAG_NODEEP_SCRUB))