SERVER-16602: Update WiredTiger default settings.

* Enable up to 4 eviction threads
* Reduce memory_page_max from 100MB to 10MB
* Update split_pct on collections to be 90, rather than 75

2 files changed, 7 insertions, 1 deletions

diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
index 74dde6db5ee..921847f1992 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
@@ -146,6 +146,7 @@ namespace mongo {
         ss << "create,";
         ss << "cache_size=" << cacheSizeGB << "G,";
         ss << "session_max=20000,";
+        ss << "eviction=(threads_max=4),";
         ss << "statistics=(fast),";
         if ( _durable ) {
             ss << "log=(enabled=true,archive=true,path=journal,compressor=";
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_record_store.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_record_store.cpp
index 59672bdf8df..bc5b647b4a1 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_record_store.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_record_store.cpp
@@ -91,7 +91,12 @@ namespace {
         // override values in the prefix, but not values in the suffix.
         str::stream ss;
         ss << "type=file,";
-        ss << "memory_page_max=100m,";
+        // Setting this larger than 10m can hurt latencies and throughput degradation if this
+        // is the oplog.  See SERVER-16247
+        ss << "memory_page_max=10m,";
+        // Choose a higher split percent, since most usage is append only. Allow some space
+        // for workloads where updates increase the size of documents.
+        ss << "split_pct=90,";
         ss << "leaf_value_max=1MB,";
         if (wiredTigerGlobalOptions.useCollectionPrefixCompression) {
             ss << "prefix_compression,";