No need for VSL infrastructure if LRU does not log

src/fellow_cache.c

@@ -3237,7 +3237,9 @@ static void *
 fellow_cache_lru_thread(struct worker *wrk, void *priv)
 {
 	struct fellow_cache_lru *lru;
+#ifdef LRU_NOISE
 	struct vsl_log vsl;
+#endif
 	struct buddy_reqs *reqs;
 	const struct fellow_cache *fc;
 	buddy_t *buddy;
@@ -3262,9 +3264,11 @@ fellow_cache_lru_thread(struct worker *wrk, void *priv)
 	reqs = BUDDY_REQS_STK(buddy, BUDDY_REQS_MAX);
 	BUDDY_REQS_PRI(reqs, FEP_RESERVE);
 
+#ifdef LRU_NOISE
 	AZ(wrk->vsl);
 	wrk->vsl = &vsl;
 	VSL_Setup(wrk->vsl, NULL, (size_t)0);
+#endif
 
 	while (fc->running) {
 		cb = fc->tune->chunk_exponent;
@@ -3314,9 +3318,9 @@ fellow_cache_lru_thread(struct worker *wrk, void *priv)
 		if (nr)
 			VSLb(wrk->vsl, SLT_Debug,
 			    "sfemem reserve fill: %u", filled);
-#endif
 
 		VSL_Flush(wrk->vsl, 0);
+#endif
 		stvfe_sumstat(wrk);
 		buddy_wait_needspace(buddy);