diff --git a/src/bees-context.cc b/src/bees-context.cc
index 9823011..fd360c5 100644
--- a/src/bees-context.cc
+++ b/src/bees-context.cc
@@ -29,13 +29,14 @@ BeesFdCache::BeesFdCache()
 		BEESCOUNTADD(open_root_ms, open_timer.age() * 1000);
 		return rv;
 	});
+	m_root_cache.max_size(BEES_ROOT_FD_CACHE_SIZE);
 	m_file_cache.func([&](shared_ptr<BeesContext> ctx, uint64_t root, uint64_t ino) -> Fd {
 		Timer open_timer;
 		auto rv = ctx->roots()->open_root_ino_nocache(root, ino);
 		BEESCOUNTADD(open_ino_ms, open_timer.age() * 1000);
 		return rv;
 	});
-	m_file_cache.max_size(BEES_FD_CACHE_SIZE);
+	m_file_cache.max_size(BEES_FILE_FD_CACHE_SIZE);
 }
 
 Fd
diff --git a/src/bees.cc b/src/bees.cc
index ea3e10c..91534ae 100644
--- a/src/bees.cc
+++ b/src/bees.cc
@@ -19,6 +19,10 @@
 #include <linux/fs.h>
 #include <sys/ioctl.h>
 
+// setrlimit
+#include <sys/time.h>
+#include <sys/resource.h>
+
 #include <getopt.h>
 
 using namespace crucible;
@@ -647,6 +651,17 @@ bees_main(int argc, char *argv[])
 		BEESLOG("using relative path " << relative_path() << "\n");
 	}
 
+	BEESLOG("setting rlimit NOFILE to " << BEES_OPEN_FILE_LIMIT);
+
+	struct rlimit lim = {
+		.rlim_cur = BEES_OPEN_FILE_LIMIT,
+		.rlim_max = BEES_OPEN_FILE_LIMIT,
+	};
+	int rv = setrlimit(RLIMIT_NOFILE, &lim);
+	if (rv) {
+		BEESLOG("setrlimit(RLIMIT_NOFILE, { " << lim.rlim_cur << " }): " << strerror(errno));
+	};
+
 	// Create a context and start crawlers
 	bool did_subscription = false;
 	while (optind < argc) {
diff --git a/src/bees.h b/src/bees.h
index 04af577..53ed33c 100644
--- a/src/bees.h
+++ b/src/bees.h
@@ -75,14 +75,25 @@ const int BEES_PROGRESS_INTERVAL = BEES_STATS_INTERVAL;
 // Status is output every freakin second.  Use a ramdisk.
 const int BEES_STATUS_INTERVAL = 1;
 
-// Number of FDs to open (not counting 100 roots)
-const size_t BEES_FD_CACHE_SIZE = 384;
+// Number of file FDs to cache when not in active use
+const size_t BEES_FILE_FD_CACHE_SIZE = 4096;
+
+// Number of root FDs to cache when not in active use
+const size_t BEES_ROOT_FD_CACHE_SIZE = 1024;
+
+// Number of FDs to open (rlimit)
+const size_t BEES_OPEN_FILE_LIMIT = (BEES_FILE_FD_CACHE_SIZE + BEES_ROOT_FD_CACHE_SIZE) * 2 + 100;
+
+// Worker thread limit (more threads may be created, but only this number will be active concurrently)
+const size_t BEES_WORKER_THREAD_LIMIT = 128;
 
 // Log warnings when an operation takes too long
 const double BEES_TOO_LONG = 2.5;
 
 // Avoid any extent where LOGICAL_INO takes this long
-const double BEES_TOXIC_DURATION = 9.9;
+// const double BEES_TOXIC_DURATION = 9.9;
+// EXPERIMENT:  Kernel v4.14+ may let us ignore toxicity
+const double BEES_TOXIC_DURATION = BEES_COMMIT_INTERVAL;
 
 // How long between hash table histograms
 const double BEES_HASH_TABLE_ANALYZE_INTERVAL = BEES_STATS_INTERVAL;