Revert "SERVER-23391 Lower WiredTiger cache size floor"

This reverts commit 5ee7b56b5b625dc62ef80ce4f5742ab837097567.

2 files changed, 7 insertions, 10 deletions

diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_init.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_init.cpp
index fffbf9c3fc9..5ccc1093549 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_init.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_init.cpp
@@ -62,27 +62,24 @@ public:
         }
 
         size_t cacheSizeGB = wiredTigerGlobalOptions.cacheSizeGB;
-        size_t cacheSizeMB = 256;  // minimum cache size
         if (cacheSizeGB == 0) {
             // Since the user didn't provide a cache size, choose a reasonable default value.
             // We want to reserve 1GB for the system and binaries, but it's not bad to
             // leave a fair amount left over for pagecache since that's compressed storage.
-            // If ProcessInfo indicates that there is < 2GB of memory, allocate 256M for cache.
-            // If ProcessInfo indicates exactly 2GB, allocate 614MB
             ProcessInfo pi;
             double memSizeMB = pi.getMemSizeMB();
-            if (memSizeMB >= 1024 * 2) {
+            if (memSizeMB > 0) {
                 double cacheMB = (memSizeMB - 1024) * 0.6;
-                cacheSizeMB = static_cast<size_t>(cacheMB);
+                cacheSizeGB = static_cast<size_t>(cacheMB / 1024);
+                if (cacheSizeGB < 1)
+                    cacheSizeGB = 1;
             }
-        } else {
-            cacheSizeMB = 1024 * cacheSizeGB;
         }
         const bool ephemeral = false;
         WiredTigerKVEngine* kv = new WiredTigerKVEngine(getCanonicalName().toString(),
                                                         params.dbpath,
                                                         wiredTigerGlobalOptions.engineConfig,
-                                                        cacheSizeMB,
+                                                        cacheSizeGB,
                                                         params.dur,
                                                         ephemeral,
                                                         params.repair,
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
index d8547c421f9..51749294c3d 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
@@ -171,7 +171,7 @@ TicketServerParameter openReadTransactionParam(&openReadTransaction,
 WiredTigerKVEngine::WiredTigerKVEngine(const std::string& canonicalName,
                                        const std::string& path,
                                        const std::string& extraOpenOptions,
-                                       size_t cacheSizeMB,
+                                       size_t cacheSizeGB,
                                        bool durable,
                                        bool ephemeral,
                                        bool repair,
@@ -200,7 +200,7 @@ WiredTigerKVEngine::WiredTigerKVEngine(const std::string& canonicalName,
 
     std::stringstream ss;
     ss << "create,";
-    ss << "cache_size=" << cacheSizeMB << "M,";
+    ss << "cache_size=" << cacheSizeGB << "G,";
     ss << "session_max=20000,";
     ss << "eviction=(threads_max=4),";
     ss << "config_base=false,";