From: Sage Weil <sage@inktank.com>
Date: Fri, 2 May 2014 00:24:48 +0000 (-0700)
Subject: osd: prevent pgs from getting too far ahead of the min pg epoch
X-Git-Tag: v0.81~59^2~3
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=cf25bdf6b0090379903981fe8cee5ea75efd7ba0;p=ceph.git

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>
---

diff --git a/src/common/config_opts.h b/src/common/config_opts.h
index 2d2f360a1602..3ef364c6d0ad 100644
--- a/src/common/config_opts.h
+++ b/src/common/config_opts.h
@@ -448,6 +448,7 @@ 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 5f9c258e4048..685e6081aa0d 100644
--- a/src/osd/OSD.cc
+++ b/src/osd/OSD.cc
@@ -5697,7 +5697,7 @@ 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,
@@ -5708,11 +5708,19 @@ 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)
@@ -5746,6 +5754,13 @@ 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;
 }
 
 /** 
@@ -7722,8 +7737,9 @@ 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 db433517af84..9ff5f27dd692 100644
--- a/src/osd/OSD.h
+++ b/src/osd/OSD.h
@@ -1287,7 +1287,7 @@ 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,