osd: prevent pgs from getting too far ahead of the min pg epoch

Bound the range of PG epochs between the slowest and fastest pg
(epoch-wise) with 'osd map max advance'.  This value should be set to
something less than 'osd map cache size' so that the maps we are
processing will be in memory as many PGs advance forward in time in
loose synchrony.

This is part of the solution to #7576.

Signed-off-by: Sage Weil <sage@inktank.com>
(cherry picked from commit cf25bdf6b0090379903981fe8cee5ea75efd7ba0)

diff --git a/src/common/config_opts.h b/src/common/config_opts.h
index fdd35575dfe9a0dc5f5fadf72d3f2f257353847f..0d328e07583b3bc776aaa84fb9d224a572ab74bc 100644 (file)
--- a/src/common/config_opts.h
+++ b/src/common/config_opts.h
@@ -451,6 +451,7 @@ OPTION(osd_tier_default_cache_hit_set_period, OPT_INT, 1200)
 OPTION(osd_tier_default_cache_hit_set_type, OPT_STR, "bloom")
 
 OPTION(osd_map_dedup, OPT_BOOL, true)
+OPTION(osd_map_max_advance, OPT_INT, 200) // make this < cache_size!
 OPTION(osd_map_cache_size, OPT_INT, 500)
 OPTION(osd_map_message_max, OPT_INT, 100)  // max maps per MOSDMap message
 OPTION(osd_map_share_max_epochs, OPT_INT, 100)  // cap on # of inc maps we send to peers, clients

diff --git a/src/osd/OSD.cc b/src/osd/OSD.cc
index 747894acf6dcff156388a1a8685a6fc577a64f41..9bcee749ed557291fd99b2df3ad400a80aabb930 100644 (file)
--- a/src/osd/OSD.cc
+++ b/src/osd/OSD.cc
@@ -5752,7 +5752,7 @@ void OSD::check_osdmap_features(ObjectStore *fs)
   }
 }
 
-void OSD::advance_pg(
+bool OSD::advance_pg(
   epoch_t osd_epoch, PG *pg,
   ThreadPool::TPHandle &handle,
   PG::RecoveryCtx *rctx,
@@ -5763,11 +5763,19 @@ void OSD::advance_pg(
   OSDMapRef lastmap = pg->get_osdmap();
 
   if (lastmap->get_epoch() == osd_epoch)
-    return;
+    return true;
   assert(lastmap->get_epoch() < osd_epoch);
 
+  epoch_t min_epoch = service.get_min_pg_epoch();
+  epoch_t max;
+  if (min_epoch) {
+    max = min_epoch + g_conf->osd_map_max_advance;
+  } else {
+    max = next_epoch + g_conf->osd_map_max_advance;
+  }
+
   for (;
-       next_epoch <= osd_epoch;
+       next_epoch <= osd_epoch && next_epoch <= max;
        ++next_epoch) {
     OSDMapRef nextmap = service.try_get_map(next_epoch);
     if (!nextmap)
@@ -5801,6 +5809,13 @@ void OSD::advance_pg(
   }
   service.pg_update_epoch(pg->info.pgid, lastmap->get_epoch());
   pg->handle_activate_map(rctx);
+  if (next_epoch <= osd_epoch) {
+    dout(10) << __func__ << " advanced by max " << g_conf->osd_map_max_advance
+            << " past min epoch " << min_epoch
+            << " ... will requeue " << *pg << dendl;
+    return false;
+  }
+  return true;
 }
 
 /** 
@@ -7813,8 +7828,9 @@ void OSD::process_peering_events(
       pg->unlock();
       continue;
     }
-    advance_pg(curmap->get_epoch(), pg, handle, &rctx, &split_pgs);
-    if (!pg->peering_queue.empty()) {
+    if (!advance_pg(curmap->get_epoch(), pg, handle, &rctx, &split_pgs)) {
+      pg->queue_null(curmap->get_epoch(), curmap->get_epoch());
+    } else if (!pg->peering_queue.empty()) {
       PG::CephPeeringEvtRef evt = pg->peering_queue.front();
       pg->peering_queue.pop_front();
       pg->handle_peering_event(evt, &rctx);

diff --git a/src/osd/OSD.h b/src/osd/OSD.h
index bc3eb4eaa74f4aa207c8577f883255f6b2d48b84..bd994df7cba8dcc433166799ed441af10e9080a1 100644 (file)
--- a/src/osd/OSD.h
+++ b/src/osd/OSD.h
@@ -1291,7 +1291,7 @@ private:
   void note_down_osd(int osd);
   void note_up_osd(int osd);
   
-  void advance_pg(
+  bool advance_pg(
     epoch_t advance_to, PG *pg,
     ThreadPool::TPHandle &handle,
     PG::RecoveryCtx *rctx,