Introduce read/write kstats per dataset

The following patch introduces a few statistics on reads and writes
grouped by dataset. These statistics are implemented as kstats
(backed by aggregate sums for performance) and can be retrieved by
using the dataset objset ID number. The motivation for this change is
to provide some preliminary analytics on dataset usage/performance.

Reviewed-by: Richard Elling <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>
Signed-off-by: Serapheim Dimitropoulos <[email protected]>
Closes #7705 

1 files changed, 59 insertions, 0 deletions

diff --git a/include/sys/dataset_kstats.h b/include/sys/dataset_kstats.h
new file mode 100644
index 000000000..5dd9a8e61
--- /dev/null
+++ b/include/sys/dataset_kstats.h
@@ -0,0 +1,59 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2018 by Delphix. All rights reserved.
+ */
+
+#ifndef _SYS_DATASET_KSTATS_H
+#define	_SYS_DATASET_KSTATS_H
+
+#include <sys/aggsum.h>
+#include <sys/dmu.h>
+#include <sys/kstat.h>
+
+typedef struct dataset_aggsum_stats_t {
+	aggsum_t das_writes;
+	aggsum_t das_nwritten;
+	aggsum_t das_reads;
+	aggsum_t das_nread;
+} dataset_aggsum_stats_t;
+
+typedef struct dataset_kstat_values {
+	kstat_named_t dkv_ds_name;
+	kstat_named_t dkv_writes;
+	kstat_named_t dkv_nwritten;
+	kstat_named_t dkv_reads;
+	kstat_named_t dkv_nread;
+} dataset_kstat_values_t;
+
+typedef struct dataset_kstats {
+	dataset_aggsum_stats_t dk_aggsums;
+	kstat_t *dk_kstats;
+} dataset_kstats_t;
+
+void dataset_kstats_create(dataset_kstats_t *, objset_t *);
+void dataset_kstats_destroy(dataset_kstats_t *);
+
+void dataset_kstats_update_write_kstats(dataset_kstats_t *, int64_t);
+void dataset_kstats_update_read_kstats(dataset_kstats_t *, int64_t);
+
+#endif /* _SYS_DATASET_KSTATS_H */