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1 | /* |
2 | * Copyright (C) 2016 CNEX Labs | |
3 | * Initial release: Javier Gonzalez <javier@cnexlabs.com> | |
4 | * Matias Bjorling <matias@cnexlabs.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License version | |
8 | * 2 as published by the Free Software Foundation. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, but | |
11 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | * General Public License for more details. | |
14 | * | |
15 | * pblk-rl.c - pblk's rate limiter for user I/O | |
16 | * | |
17 | */ | |
18 | ||
19 | #include "pblk.h" | |
20 | ||
21 | static void pblk_rl_kick_u_timer(struct pblk_rl *rl) | |
22 | { | |
23 | mod_timer(&rl->u_timer, jiffies + msecs_to_jiffies(5000)); | |
24 | } | |
25 | ||
26 | int pblk_rl_user_may_insert(struct pblk_rl *rl, int nr_entries) | |
27 | { | |
28 | int rb_user_cnt = atomic_read(&rl->rb_user_cnt); | |
29 | ||
30 | return (!(rb_user_cnt + nr_entries > rl->rb_user_max)); | |
31 | } | |
32 | ||
33 | int pblk_rl_gc_may_insert(struct pblk_rl *rl, int nr_entries) | |
34 | { | |
35 | int rb_gc_cnt = atomic_read(&rl->rb_gc_cnt); | |
36 | int rb_user_active; | |
37 | ||
38 | /* If there is no user I/O let GC take over space on the write buffer */ | |
39 | rb_user_active = READ_ONCE(rl->rb_user_active); | |
40 | return (!(rb_gc_cnt + nr_entries > rl->rb_gc_max && rb_user_active)); | |
41 | } | |
42 | ||
43 | void pblk_rl_user_in(struct pblk_rl *rl, int nr_entries) | |
44 | { | |
45 | atomic_add(nr_entries, &rl->rb_user_cnt); | |
46 | ||
47 | /* Release user I/O state. Protect from GC */ | |
48 | smp_store_release(&rl->rb_user_active, 1); | |
49 | pblk_rl_kick_u_timer(rl); | |
50 | } | |
51 | ||
52 | void pblk_rl_gc_in(struct pblk_rl *rl, int nr_entries) | |
53 | { | |
54 | atomic_add(nr_entries, &rl->rb_gc_cnt); | |
55 | } | |
56 | ||
57 | void pblk_rl_out(struct pblk_rl *rl, int nr_user, int nr_gc) | |
58 | { | |
59 | atomic_sub(nr_user, &rl->rb_user_cnt); | |
60 | atomic_sub(nr_gc, &rl->rb_gc_cnt); | |
61 | } | |
62 | ||
63 | unsigned long pblk_rl_nr_free_blks(struct pblk_rl *rl) | |
64 | { | |
65 | return atomic_read(&rl->free_blocks); | |
66 | } | |
67 | ||
68 | /* | |
69 | * We check for (i) the number of free blocks in the current LUN and (ii) the | |
70 | * total number of free blocks in the pblk instance. This is to even out the | |
71 | * number of free blocks on each LUN when GC kicks in. | |
72 | * | |
73 | * Only the total number of free blocks is used to configure the rate limiter. | |
74 | */ | |
75 | static int pblk_rl_update_rates(struct pblk_rl *rl, unsigned long max) | |
76 | { | |
77 | unsigned long free_blocks = pblk_rl_nr_free_blks(rl); | |
78 | ||
79 | if (free_blocks >= rl->high) { | |
80 | rl->rb_user_max = max - rl->rb_gc_rsv; | |
81 | rl->rb_gc_max = rl->rb_gc_rsv; | |
82 | rl->rb_state = PBLK_RL_HIGH; | |
83 | } else if (free_blocks < rl->high) { | |
84 | int shift = rl->high_pw - rl->rb_windows_pw; | |
85 | int user_windows = free_blocks >> shift; | |
86 | int user_max = user_windows << PBLK_MAX_REQ_ADDRS_PW; | |
87 | int gc_max; | |
88 | ||
89 | rl->rb_user_max = user_max; | |
90 | gc_max = max - rl->rb_user_max; | |
91 | rl->rb_gc_max = max(gc_max, rl->rb_gc_rsv); | |
92 | ||
93 | if (free_blocks > rl->low) | |
94 | rl->rb_state = PBLK_RL_MID; | |
95 | else | |
96 | rl->rb_state = PBLK_RL_LOW; | |
97 | } | |
98 | ||
99 | return rl->rb_state; | |
100 | } | |
101 | ||
102 | void pblk_rl_set_gc_rsc(struct pblk_rl *rl, int rsv) | |
103 | { | |
104 | rl->rb_gc_rsv = rl->rb_gc_max = rsv; | |
105 | } | |
106 | ||
107 | void pblk_rl_free_lines_inc(struct pblk_rl *rl, struct pblk_line *line) | |
108 | { | |
109 | struct pblk *pblk = container_of(rl, struct pblk, rl); | |
a44f53fa | 110 | int blk_in_line = atomic_read(&line->blk_in_line); |
a4bd217b JG |
111 | int ret; |
112 | ||
a44f53fa | 113 | atomic_add(blk_in_line, &rl->free_blocks); |
a4bd217b JG |
114 | /* Rates will not change that often - no need to lock update */ |
115 | ret = pblk_rl_update_rates(rl, rl->rb_budget); | |
116 | ||
117 | if (ret == (PBLK_RL_MID | PBLK_RL_LOW)) | |
118 | pblk_gc_should_start(pblk); | |
119 | else | |
120 | pblk_gc_should_stop(pblk); | |
121 | } | |
122 | ||
123 | void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line) | |
124 | { | |
125 | struct pblk *pblk = container_of(rl, struct pblk, rl); | |
a44f53fa | 126 | int blk_in_line = atomic_read(&line->blk_in_line); |
a4bd217b JG |
127 | int ret; |
128 | ||
a44f53fa | 129 | atomic_sub(blk_in_line, &rl->free_blocks); |
a4bd217b JG |
130 | |
131 | /* Rates will not change that often - no need to lock update */ | |
132 | ret = pblk_rl_update_rates(rl, rl->rb_budget); | |
133 | if (ret == (PBLK_RL_MID | PBLK_RL_LOW)) | |
134 | pblk_gc_should_start(pblk); | |
135 | else | |
136 | pblk_gc_should_stop(pblk); | |
137 | } | |
138 | ||
139 | int pblk_rl_gc_thrs(struct pblk_rl *rl) | |
140 | { | |
141 | return rl->high; | |
142 | } | |
143 | ||
144 | int pblk_rl_sysfs_rate_show(struct pblk_rl *rl) | |
145 | { | |
146 | return rl->rb_user_max; | |
147 | } | |
148 | ||
149 | static void pblk_rl_u_timer(unsigned long data) | |
150 | { | |
151 | struct pblk_rl *rl = (struct pblk_rl *)data; | |
152 | ||
153 | /* Release user I/O state. Protect from GC */ | |
154 | smp_store_release(&rl->rb_user_active, 0); | |
155 | } | |
156 | ||
157 | void pblk_rl_free(struct pblk_rl *rl) | |
158 | { | |
159 | del_timer(&rl->u_timer); | |
160 | } | |
161 | ||
162 | void pblk_rl_init(struct pblk_rl *rl, int budget) | |
163 | { | |
164 | unsigned int rb_windows; | |
165 | ||
166 | rl->high = rl->total_blocks / PBLK_USER_HIGH_THRS; | |
167 | rl->low = rl->total_blocks / PBLK_USER_LOW_THRS; | |
168 | rl->high_pw = get_count_order(rl->high); | |
169 | ||
170 | /* This will always be a power-of-2 */ | |
171 | rb_windows = budget / PBLK_MAX_REQ_ADDRS; | |
172 | rl->rb_windows_pw = get_count_order(rb_windows) + 1; | |
173 | ||
174 | /* To start with, all buffer is available to user I/O writers */ | |
175 | rl->rb_budget = budget; | |
176 | rl->rb_user_max = budget; | |
177 | atomic_set(&rl->rb_user_cnt, 0); | |
178 | rl->rb_gc_max = 0; | |
179 | rl->rb_state = PBLK_RL_HIGH; | |
180 | atomic_set(&rl->rb_gc_cnt, 0); | |
181 | ||
182 | setup_timer(&rl->u_timer, pblk_rl_u_timer, (unsigned long)rl); | |
183 | rl->rb_user_active = 0; | |
184 | } |