1 // SPDX-License-Identifier: CDDL-1.0
2 /*
3 * CDDL HEADER START
4 *
5 * This file and its contents are supplied under the terms of the
6 * Common Development and Distribution License ("CDDL"), version 1.0.
7 * You may only use this file in accordance with the terms of version
8 * 1.0 of the CDDL.
9 *
10 * A full copy of the text of the CDDL should have accompanied this
11 * source. A copy of the CDDL is also available via the Internet at
12 * http://www.illumos.org/license/CDDL.
13 *
14 * CDDL HEADER END
15 */
16
17 /*
18 * wmsum counters are a reduced version of aggsum counters, optimized for
19 * write-mostly scenarios. They do not provide optimized read functions,
20 * but instead allow much cheaper add function. The primary usage is
21 * infrequently read statistic counters, not requiring exact precision.
22 *
23 * The Linux implementation is directly mapped into percpu_counter KPI.
24 */
25
26 #ifndef _SYS_WMSUM_H
27 #define _SYS_WMSUM_H
28
29 #include <linux/percpu_counter.h>
30
31 #ifdef __cplusplus
32 extern "C" {
33 #endif
34
35 typedef struct percpu_counter wmsum_t;
36
37 static inline void
wmsum_init(wmsum_t * ws,uint64_t value)38 wmsum_init(wmsum_t *ws, uint64_t value)
39 {
40 percpu_counter_init(ws, value, GFP_KERNEL);
41 }
42
43 static inline void
wmsum_fini(wmsum_t * ws)44 wmsum_fini(wmsum_t *ws)
45 {
46
47 percpu_counter_destroy(ws);
48 }
49
50 static inline uint64_t
wmsum_value(wmsum_t * ws)51 wmsum_value(wmsum_t *ws)
52 {
53
54 return (percpu_counter_sum(ws));
55 }
56
57 static inline void
wmsum_add(wmsum_t * ws,int64_t delta)58 wmsum_add(wmsum_t *ws, int64_t delta)
59 {
60
61 percpu_counter_add_batch(ws, delta, INT_MAX / 2);
62 }
63
64 #ifdef __cplusplus
65 }
66 #endif
67
68 #endif /* _SYS_WMSUM_H */
69