Add kstats tracking gang allocations

Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Signed-off-by: Paul Dagnelie <[email protected]>
openzfs · Jan 28, 2025 · eb47f59 · eb47f59
1 parent fe44c5a
commit eb47f59
Showing 1 changed file with 29 additions and 0 deletions.
diff --git a/module/zfs/zio.c b/module/zfs/zio.c
@@ -145,6 +145,21 @@ static const int zio_buf_debug_limit = 16384;
 static const int zio_buf_debug_limit = 0;
 #endif
 
+typedef struct zio_stats {
+	kstat_named_t ziostat_gang_writes;
+	kstat_named_t ziostat_gang_multilevel;
+} zio_stats_t;
+
+static zio_stats_t zio_stats = {
+	{ "gang_writes",	KSTAT_DATA_UINT64 },
+	{ "gang_multilevel",	KSTAT_DATA_UINT64 },
+};
+
+#define	ZIOSTAT_BUMP(stat) \
+	atomic_inc_64(&zio_stats.stat.value.ui64);
+
+static kstat_t *zio_ksp;
+
 static inline void __zio_execute(zio_t *zio);
 
 static void zio_taskq_dispatch(zio_t *, zio_taskq_type_t, boolean_t);
@@ -158,6 +173,13 @@ zio_init(void)
 	    sizeof (zio_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
 	zio_link_cache = kmem_cache_create("zio_link_cache",
 	    sizeof (zio_link_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
+	zio_ksp = kstat_create("zfs", 0, "zio_stats",
+	    "misc", KSTAT_TYPE_NAMED, sizeof (zio_stats) /
+	    sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
+	if (zio_ksp != NULL) {
+		zio_ksp->ks_data = &zio_stats;
+		kstat_install(zio_ksp);
+	}
 
 	for (c = 0; c < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT; c++) {
 		size_t size = (c + 1) << SPA_MINBLOCKSHIFT;
@@ -286,6 +308,10 @@ zio_fini(void)
 		VERIFY3P(zio_data_buf_cache[i], ==, NULL);
 	}
 
+	if (zio_ksp != NULL) {
+		kstat_delete(zio_ksp);
+		zio_ksp = NULL;
+	}
 	kmem_cache_destroy(zio_link_cache);
 	kmem_cache_destroy(zio_cache);
 
@@ -4114,6 +4140,9 @@ zio_dva_allocate(zio_t *zio)
 			    spa_name(spa), zio, (u_longlong_t)zio->io_size,
 			    error);
 		}
+		ZIOSTAT_BUMP(ziostat_gang_writes);
+		if (flags & METASLAB_GANG_CHILD)
+			ZIOSTAT_BUMP(ziostat_gang_multilevel);
 		return (zio_write_gang_block(zio, mc));
 	}
 	if (error != 0) {