Add a config threshold for running periodic NFS GC

Summary:
We want to add a threshold config to the number of inodes on NFS, and the periodic NFS GC only runs if the number of inodes is higher than this number for a mount.
This diff makes periodic NFS GC less aggressive.

Reviewed By: genevievehelsel

Differential Revision: D75610448

fbshipit-source-id: baf526d90c0b6fe34825ef5369899949ca578552

Author: kavehahmadi60

eden/fs/config/EdenConfig.h

@@ -442,6 +442,17 @@ class EdenConfig : private ConfigSettingManager {
       std::chrono::hours(1),
       this};
 
+  /**
+   * Mininum number of inodes that need to be loaded  before triggering the
+   * periodic NFS Garbage Collector (GC). If the loaded inode count is below
+   * this number, a GC will be skipped. A value of 0 will effectively skip this
+   * check.
+   */
+  ConfigSetting<uint64_t> nfsPeriodicGcLoadedInodesThreshold{
+      "mount:nfs-periodic-gc-loaded-inodes-threshold",
+      1000000,
+      this};
+
   /**
    * Files with an atime older than this will be invalidated during GC.
    *

eden/fs/service/EdenServer.cpp

@@ -2794,6 +2794,19 @@ void EdenServer::garbageCollectAllMounts() {
 
   auto mountPoints = getMountPoints();
   for (auto& mountHandle : mountPoints) {
+#ifdef __APPLE__
+    // On macOS, we don't want to run periodic GC if the number of inodes for
+    // the mount is below the threshold.
+    auto inodeCountsBeforeGC =
+        mountHandle.getEdenMount().getInodeMap()->getInodeCounts();
+    auto totalNumberOfInodesBeforeGC = inodeCountsBeforeGC.fileCount +
+        inodeCountsBeforeGC.treeCount + inodeCountsBeforeGC.unloadedInodeCount;
+    auto nfsPeriodicGcLoadedInodesThreshold =
+        config->nfsPeriodicGcLoadedInodesThreshold.getValue();
+    if (totalNumberOfInodesBeforeGC < nfsPeriodicGcLoadedInodesThreshold) {
+      continue;
+    }
+#endif
     folly::via(
         getServerState()->getThreadPool().get(),
         [this, mountHandle, cutoff]() mutable {