drivers/lightnvm/pblk-rl.c

   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_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
  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);
  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;
  45
  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);
  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);
  64         return (!(rb_gc_cnt >= rl->rb_gc_max && rb_user_active));
  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_werr_line_in(struct pblk_rl *rl)
  77 {
  78         atomic_inc(&rl->werr_lines);
  79 }
  80
  81 void pblk_rl_werr_line_out(struct pblk_rl *rl)
  82 {
  83         atomic_dec(&rl->werr_lines);
  84 }
  85
  86 void pblk_rl_gc_in(struct pblk_rl *rl, int nr_entries)
  87 {
  88         atomic_add(nr_entries, &rl->rb_gc_cnt);
  89 }
  90
  91 void pblk_rl_out(struct pblk_rl *rl, int nr_user, int nr_gc)
  92 {
  93         atomic_sub(nr_user, &rl->rb_user_cnt);
  94         atomic_sub(nr_gc, &rl->rb_gc_cnt);
  95 }
  96
  97 unsigned long pblk_rl_nr_free_blks(struct pblk_rl *rl)
  98 {
  99         return atomic_read(&rl->free_blocks);
 100 }
 101
 102 unsigned long pblk_rl_nr_user_free_blks(struct pblk_rl *rl)
 103 {
 104         return atomic_read(&rl->free_user_blocks);
 105 }
 106
 107 static void __pblk_rl_update_rates(struct pblk_rl *rl,
 108                                    unsigned long free_blocks)
 109 {
 110         struct pblk *pblk = container_of(rl, struct pblk, rl);
 111         int max = rl->rb_budget;
 112         int werr_gc_needed = atomic_read(&rl->werr_lines);
 113
 114         if (free_blocks >= rl->high) {
 115                 if (werr_gc_needed) {
 116                         /* Allocate a small budget for recovering
 117                          * lines with write errors
 118                          */
 119                         rl->rb_gc_max = 1 << rl->rb_windows_pw;
 120                         rl->rb_user_max = max - rl->rb_gc_max;
 121                         rl->rb_state = PBLK_RL_WERR;
 122                 } else {
 123                         rl->rb_user_max = max;
 124                         rl->rb_gc_max = 0;
 125                         rl->rb_state = PBLK_RL_OFF;
 126                 }
 127         } else if (free_blocks < rl->high) {
 128                 int shift = rl->high_pw - rl->rb_windows_pw;
 129                 int user_windows = free_blocks >> shift;
 130                 int user_max = user_windows << PBLK_MAX_REQ_ADDRS_PW;
 131
 132                 rl->rb_user_max = user_max;
 133                 rl->rb_gc_max = max - user_max;
 134
 135                 if (free_blocks <= rl->rsv_blocks) {
 136                         rl->rb_user_max = 0;
 137                         rl->rb_gc_max = max;
 138                 }
 139
 140                 /* In the worst case, we will need to GC lines in the low list
 141                  * (high valid sector count). If there are lines to GC on high
 142                  * or mid lists, these will be prioritized
 143                  */
 144                 rl->rb_state = PBLK_RL_LOW;
 145         }
 146
 147         if (rl->rb_state != PBLK_RL_OFF)
 148                 pblk_gc_should_start(pblk);
 149         else
 150                 pblk_gc_should_stop(pblk);
 151 }
 152
 153 void pblk_rl_update_rates(struct pblk_rl *rl)
 154 {
 155         __pblk_rl_update_rates(rl, pblk_rl_nr_user_free_blks(rl));
 156 }
 157
 158 void pblk_rl_free_lines_inc(struct pblk_rl *rl, struct pblk_line *line)
 159 {
 160         int blk_in_line = atomic_read(&line->blk_in_line);
 161         int free_blocks;
 162
 163         atomic_add(blk_in_line, &rl->free_blocks);
 164         free_blocks = atomic_add_return(blk_in_line, &rl->free_user_blocks);
 165
 166         __pblk_rl_update_rates(rl, free_blocks);
 167 }
 168
 169 void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line,
 170                             bool used)
 171 {
 172         int blk_in_line = atomic_read(&line->blk_in_line);
 173         int free_blocks;
 174
 175         atomic_sub(blk_in_line, &rl->free_blocks);
 176
 177         if (used)
 178                 free_blocks = atomic_sub_return(blk_in_line,
 179                                                         &rl->free_user_blocks);
 180         else
 181                 free_blocks = atomic_read(&rl->free_user_blocks);
 182
 183         __pblk_rl_update_rates(rl, free_blocks);
 184 }
 185
 186 int pblk_rl_high_thrs(struct pblk_rl *rl)
 187 {
 188         return rl->high;
 189 }
 190
 191 int pblk_rl_max_io(struct pblk_rl *rl)
 192 {
 193         return rl->rb_max_io;
 194 }
 195
 196 static void pblk_rl_u_timer(struct timer_list *t)
 197 {
 198         struct pblk_rl *rl = from_timer(rl, t, u_timer);
 199
 200         /* Release user I/O state. Protect from GC */
 201         smp_store_release(&rl->rb_user_active, 0);
 202 }
 203
 204 void pblk_rl_free(struct pblk_rl *rl)
 205 {
 206         del_timer(&rl->u_timer);
 207 }
 208
 209 void pblk_rl_init(struct pblk_rl *rl, int budget)
 210 {
 211         struct pblk *pblk = container_of(rl, struct pblk, rl);
 212         struct nvm_tgt_dev *dev = pblk->dev;
 213         struct nvm_geo *geo = &dev->geo;
 214         struct pblk_line_mgmt *l_mg = &pblk->l_mg;
 215         struct pblk_line_meta *lm = &pblk->lm;
 216         int min_blocks = lm->blk_per_line * PBLK_GC_RSV_LINE;
 217         int sec_meta, blk_meta;
 218
 219         unsigned int rb_windows;
 220
 221         /* Consider sectors used for metadata */
 222         sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;
 223         blk_meta = DIV_ROUND_UP(sec_meta, geo->clba);
 224
 225         rl->high = pblk->op_blks - blk_meta - lm->blk_per_line;
 226         rl->high_pw = get_count_order(rl->high);
 227
 228         rl->rsv_blocks = min_blocks;
 229
 230         /* This will always be a power-of-2 */
 231         rb_windows = budget / PBLK_MAX_REQ_ADDRS;
 232         rl->rb_windows_pw = get_count_order(rb_windows);
 233
 234         /* To start with, all buffer is available to user I/O writers */
 235         rl->rb_budget = budget;
 236         rl->rb_user_max = budget;
 237         rl->rb_max_io = budget >> 1;
 238         rl->rb_gc_max = 0;
 239         rl->rb_state = PBLK_RL_HIGH;
 240
 241         atomic_set(&rl->rb_user_cnt, 0);
 242         atomic_set(&rl->rb_gc_cnt, 0);
 243         atomic_set(&rl->rb_space, -1);
 244         atomic_set(&rl->werr_lines, 0);
 245
 246         timer_setup(&rl->u_timer, pblk_rl_u_timer, 0);
 247
 248         rl->rb_user_active = 0;
 249         rl->rb_gc_active = 0;
 250 }