HPA: Fix typos with big performance implications.

This fixes two simple but significant typos in the HPA:
- The conf string parsing accidentally set a min value of PAGE for
  hpa_sec_batch_fill_extra; i.e. allocating 4096 extra pages every time we
  attempted to allocate a single page.  This puts us over the SEC flush limit,
  so we then immediately flush all but one of them (probably triggering
  purging).
- The HPA was using the default PAI batch alloc implementation, which meant it
  did not actually get any locking advantages.

This snuck by because I did all the performance testing without using the PAI
interface or config settings.  When I cleaned it up and put everything behind
nice interfaces, I only did correctness checks, and didn't try any performance
ones.

src/hpa.c

@@ -92,7 +92,7 @@ hpa_shard_init(hpa_shard_t *shard, emap_t *emap, base_t *base,
 	 * operating on corrupted data.
 	 */
 	shard->pai.alloc = &hpa_alloc;
-	shard->pai.alloc_batch = &pai_alloc_batch_default;
+	shard->pai.alloc_batch = &hpa_alloc_batch;
 	shard->pai.expand = &hpa_expand;
 	shard->pai.shrink = &hpa_shrink;
 	shard->pai.dalloc = &hpa_dalloc;

src/jemalloc.c

@@ -1489,8 +1489,8 @@ malloc_conf_init_helper(sc_data_t *sc_data, unsigned bin_shard_sizes[SC_NBINS],
 			    "hpa_sec_bytes_after_flush", PAGE, 0,
 			    CONF_CHECK_MIN, CONF_DONT_CHECK_MAX, true);
 			CONF_HANDLE_SIZE_T(opt_hpa_sec_opts.batch_fill_extra,
-			    "hpa_sec_batch_fill_extra", PAGE, 0, CONF_CHECK_MIN,
-			    CONF_DONT_CHECK_MAX, true);
+			    "hpa_sec_batch_fill_extra", 0, HUGEPAGE_PAGES,
+			    CONF_CHECK_MIN, CONF_CHECK_MAX, true);
 
 			if (CONF_MATCH("slab_sizes")) {
 				if (CONF_MATCH_VALUE("default")) {