1 /* $NetBSD: shrinker.h,v 1.5 2021/12/19 01:22:37 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2013 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Taylor R. Campbell.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #ifndef _LINUX_SHRINKER_H_
33 #define _LINUX_SHRINKER_H_
34
35 #include <uvm/uvm.h>
36
37 struct shrink_control {
38 unsigned long nr_to_scan;
39 unsigned long nr_scanned;
40 };
41
42 struct shrinker {
43 int (*shrink)(struct shrinker *, struct shrink_control *);
44 unsigned long (*count_objects)(struct shrinker *,
45 struct shrink_control *);
46 unsigned long (*scan_objects)(struct shrinker *,
47 struct shrink_control *);
48 int seeks;
49 size_t batch;
50 };
51
52 #define SHRINK_STOP (~0UL)
53
54 #define DEFAULT_SEEKS 2 /* XXX cargo-culted from Linux */
55
56 static inline int
register_shrinker(struct shrinker * shrinker __unused)57 register_shrinker(struct shrinker *shrinker __unused)
58 {
59 return 0;
60 }
61
62 static inline void
unregister_shrinker(struct shrinker * shrinker __unused)63 unregister_shrinker(struct shrinker *shrinker __unused)
64 {
65 }
66
67 static inline bool
current_is_kswapd(void)68 current_is_kswapd(void)
69 {
70 return curlwp == uvm.pagedaemon_lwp;
71 }
72
73 static inline size_t
get_nr_swap_pages(void)74 get_nr_swap_pages(void)
75 {
76 return uvmexp.swpages;
77 }
78
79 #endif /* _LINUX_SHRINKER_H_ */
80