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a4bd217b JG |
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 | ||
588726d3 JG |
26 | int pblk_rl_is_limit(struct pblk_rl *rl) |
27 | { | |
28 | int rb_space; | |
29 | ||
30 | rb_space = atomic_read(&rl->rb_space); | |
31 | ||
32 | return (rb_space == 0); | |
33 | } | |
34 | ||
a4bd217b JG |
35 | int pblk_rl_user_may_insert(struct pblk_rl *rl, int nr_entries) |
36 | { | |
37 | int rb_user_cnt = atomic_read(&rl->rb_user_cnt); | |
588726d3 JG |
38 | int rb_space = atomic_read(&rl->rb_space); |
39 | ||
40 | if (unlikely(rb_space >= 0) && (rb_space - nr_entries < 0)) | |
41 | return NVM_IO_ERR; | |
42 | ||
43 | if (rb_user_cnt >= rl->rb_user_max) | |
44 | return NVM_IO_REQUEUE; | |
a4bd217b | 45 | |
588726d3 JG |
46 | return NVM_IO_OK; |
47 | } | |
48 | ||
49 | void pblk_rl_inserted(struct pblk_rl *rl, int nr_entries) | |
50 | { | |
51 | int rb_space = atomic_read(&rl->rb_space); | |
52 | ||
53 | if (unlikely(rb_space >= 0)) | |
54 | atomic_sub(nr_entries, &rl->rb_space); | |
a4bd217b JG |
55 | } |
56 | ||
57 | int pblk_rl_gc_may_insert(struct pblk_rl *rl, int nr_entries) | |
58 | { | |
59 | int rb_gc_cnt = atomic_read(&rl->rb_gc_cnt); | |
60 | int rb_user_active; | |
61 | ||
62 | /* If there is no user I/O let GC take over space on the write buffer */ | |
63 | rb_user_active = READ_ONCE(rl->rb_user_active); | |
b20ba1bc | 64 | return (!(rb_gc_cnt >= rl->rb_gc_max && rb_user_active)); |
a4bd217b JG |
65 | } |
66 | ||
67 | void pblk_rl_user_in(struct pblk_rl *rl, int nr_entries) | |
68 | { | |
69 | atomic_add(nr_entries, &rl->rb_user_cnt); | |
70 | ||
71 | /* Release user I/O state. Protect from GC */ | |
72 | smp_store_release(&rl->rb_user_active, 1); | |
73 | pblk_rl_kick_u_timer(rl); | |
74 | } | |
75 | ||
76 | void pblk_rl_gc_in(struct pblk_rl *rl, int nr_entries) | |
77 | { | |
78 | atomic_add(nr_entries, &rl->rb_gc_cnt); | |
79 | } | |
80 | ||
81 | void pblk_rl_out(struct pblk_rl *rl, int nr_user, int nr_gc) | |
82 | { | |
83 | atomic_sub(nr_user, &rl->rb_user_cnt); | |
84 | atomic_sub(nr_gc, &rl->rb_gc_cnt); | |
85 | } | |
86 | ||
87 | unsigned long pblk_rl_nr_free_blks(struct pblk_rl *rl) | |
88 | { | |
89 | return atomic_read(&rl->free_blocks); | |
90 | } | |
91 | ||
92 | /* | |
93 | * We check for (i) the number of free blocks in the current LUN and (ii) the | |
94 | * total number of free blocks in the pblk instance. This is to even out the | |
95 | * number of free blocks on each LUN when GC kicks in. | |
96 | * | |
97 | * Only the total number of free blocks is used to configure the rate limiter. | |
98 | */ | |
99 | static int pblk_rl_update_rates(struct pblk_rl *rl, unsigned long max) | |
100 | { | |
101 | unsigned long free_blocks = pblk_rl_nr_free_blks(rl); | |
102 | ||
103 | if (free_blocks >= rl->high) { | |
b20ba1bc JG |
104 | rl->rb_user_max = max; |
105 | rl->rb_gc_max = 0; | |
a4bd217b JG |
106 | rl->rb_state = PBLK_RL_HIGH; |
107 | } else if (free_blocks < rl->high) { | |
108 | int shift = rl->high_pw - rl->rb_windows_pw; | |
109 | int user_windows = free_blocks >> shift; | |
110 | int user_max = user_windows << PBLK_MAX_REQ_ADDRS_PW; | |
a4bd217b JG |
111 | |
112 | rl->rb_user_max = user_max; | |
b20ba1bc JG |
113 | rl->rb_gc_max = max - user_max; |
114 | ||
115 | if (free_blocks <= rl->rsv_blocks) { | |
116 | rl->rb_user_max = 0; | |
117 | rl->rb_gc_max = max; | |
118 | } | |
119 | ||
120 | /* In the worst case, we will need to GC lines in the low list | |
121 | * (high valid sector count). If there are lines to GC on high | |
122 | * or mid lists, these will be prioritized | |
123 | */ | |
124 | rl->rb_state = PBLK_RL_LOW; | |
a4bd217b JG |
125 | } |
126 | ||
127 | return rl->rb_state; | |
128 | } | |
129 | ||
a4bd217b JG |
130 | void pblk_rl_free_lines_inc(struct pblk_rl *rl, struct pblk_line *line) |
131 | { | |
132 | struct pblk *pblk = container_of(rl, struct pblk, rl); | |
a44f53fa | 133 | int blk_in_line = atomic_read(&line->blk_in_line); |
a4bd217b JG |
134 | int ret; |
135 | ||
a44f53fa | 136 | atomic_add(blk_in_line, &rl->free_blocks); |
a4bd217b JG |
137 | /* Rates will not change that often - no need to lock update */ |
138 | ret = pblk_rl_update_rates(rl, rl->rb_budget); | |
139 | ||
140 | if (ret == (PBLK_RL_MID | PBLK_RL_LOW)) | |
141 | pblk_gc_should_start(pblk); | |
142 | else | |
143 | pblk_gc_should_stop(pblk); | |
144 | } | |
145 | ||
146 | void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line) | |
147 | { | |
a44f53fa | 148 | int blk_in_line = atomic_read(&line->blk_in_line); |
a4bd217b | 149 | |
a44f53fa | 150 | atomic_sub(blk_in_line, &rl->free_blocks); |
b20ba1bc JG |
151 | } |
152 | ||
153 | void pblk_gc_should_kick(struct pblk *pblk) | |
154 | { | |
155 | struct pblk_rl *rl = &pblk->rl; | |
156 | int ret; | |
a4bd217b JG |
157 | |
158 | /* Rates will not change that often - no need to lock update */ | |
159 | ret = pblk_rl_update_rates(rl, rl->rb_budget); | |
160 | if (ret == (PBLK_RL_MID | PBLK_RL_LOW)) | |
161 | pblk_gc_should_start(pblk); | |
162 | else | |
163 | pblk_gc_should_stop(pblk); | |
164 | } | |
165 | ||
b20ba1bc | 166 | int pblk_rl_high_thrs(struct pblk_rl *rl) |
a4bd217b JG |
167 | { |
168 | return rl->high; | |
169 | } | |
170 | ||
b20ba1bc JG |
171 | int pblk_rl_low_thrs(struct pblk_rl *rl) |
172 | { | |
173 | return rl->low; | |
174 | } | |
175 | ||
a4bd217b JG |
176 | int pblk_rl_sysfs_rate_show(struct pblk_rl *rl) |
177 | { | |
178 | return rl->rb_user_max; | |
179 | } | |
180 | ||
181 | static void pblk_rl_u_timer(unsigned long data) | |
182 | { | |
183 | struct pblk_rl *rl = (struct pblk_rl *)data; | |
184 | ||
185 | /* Release user I/O state. Protect from GC */ | |
186 | smp_store_release(&rl->rb_user_active, 0); | |
187 | } | |
188 | ||
189 | void pblk_rl_free(struct pblk_rl *rl) | |
190 | { | |
191 | del_timer(&rl->u_timer); | |
192 | } | |
193 | ||
194 | void pblk_rl_init(struct pblk_rl *rl, int budget) | |
195 | { | |
b20ba1bc JG |
196 | struct pblk *pblk = container_of(rl, struct pblk, rl); |
197 | struct pblk_line_meta *lm = &pblk->lm; | |
198 | int min_blocks = lm->blk_per_line * PBLK_GC_RSV_LINE; | |
a4bd217b JG |
199 | unsigned int rb_windows; |
200 | ||
201 | rl->high = rl->total_blocks / PBLK_USER_HIGH_THRS; | |
a4bd217b JG |
202 | rl->high_pw = get_count_order(rl->high); |
203 | ||
b20ba1bc JG |
204 | rl->low = rl->total_blocks / PBLK_USER_LOW_THRS; |
205 | if (rl->low < min_blocks) | |
206 | rl->low = min_blocks; | |
207 | ||
208 | rl->rsv_blocks = min_blocks; | |
209 | ||
a4bd217b JG |
210 | /* This will always be a power-of-2 */ |
211 | rb_windows = budget / PBLK_MAX_REQ_ADDRS; | |
b20ba1bc | 212 | rl->rb_windows_pw = get_count_order(rb_windows); |
a4bd217b JG |
213 | |
214 | /* To start with, all buffer is available to user I/O writers */ | |
215 | rl->rb_budget = budget; | |
216 | rl->rb_user_max = budget; | |
a4bd217b JG |
217 | rl->rb_gc_max = 0; |
218 | rl->rb_state = PBLK_RL_HIGH; | |
588726d3 JG |
219 | |
220 | atomic_set(&rl->rb_user_cnt, 0); | |
a4bd217b | 221 | atomic_set(&rl->rb_gc_cnt, 0); |
588726d3 | 222 | atomic_set(&rl->rb_space, -1); |
a4bd217b JG |
223 | |
224 | setup_timer(&rl->u_timer, pblk_rl_u_timer, (unsigned long)rl); | |
b20ba1bc | 225 | |
a4bd217b | 226 | rl->rb_user_active = 0; |
b20ba1bc | 227 | rl->rb_gc_active = 0; |
a4bd217b | 228 | } |