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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Copyright (C) 2016 CNEX Labs
- * Initial release: Javier Gonzalez <javier@cnexlabs.com>
- * Matias Bjorling <matias@cnexlabs.com>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License version
- * 2 as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * pblk-rl.c - pblk's rate limiter for user I/O
- *
- */
- #include "pblk.h"
- static void pblk_rl_kick_u_timer(struct pblk_rl *rl)
- {
- mod_timer(&rl->u_timer, jiffies + msecs_to_jiffies(5000));
- }
- int pblk_rl_is_limit(struct pblk_rl *rl)
- {
- int rb_space;
- rb_space = atomic_read(&rl->rb_space);
- return (rb_space == 0);
- }
- int pblk_rl_user_may_insert(struct pblk_rl *rl, int nr_entries)
- {
- int rb_user_cnt = atomic_read(&rl->rb_user_cnt);
- int rb_space = atomic_read(&rl->rb_space);
- if (unlikely(rb_space >= 0) && (rb_space - nr_entries < 0))
- return NVM_IO_ERR;
- if (rb_user_cnt >= rl->rb_user_max)
- return NVM_IO_REQUEUE;
- return NVM_IO_OK;
- }
- void pblk_rl_inserted(struct pblk_rl *rl, int nr_entries)
- {
- int rb_space = atomic_read(&rl->rb_space);
- if (unlikely(rb_space >= 0))
- atomic_sub(nr_entries, &rl->rb_space);
- }
- int pblk_rl_gc_may_insert(struct pblk_rl *rl, int nr_entries)
- {
- int rb_gc_cnt = atomic_read(&rl->rb_gc_cnt);
- int rb_user_active;
- /* If there is no user I/O let GC take over space on the write buffer */
- rb_user_active = READ_ONCE(rl->rb_user_active);
- return (!(rb_gc_cnt >= rl->rb_gc_max && rb_user_active));
- }
- void pblk_rl_user_in(struct pblk_rl *rl, int nr_entries)
- {
- atomic_add(nr_entries, &rl->rb_user_cnt);
- /* Release user I/O state. Protect from GC */
- smp_store_release(&rl->rb_user_active, 1);
- pblk_rl_kick_u_timer(rl);
- }
- void pblk_rl_werr_line_in(struct pblk_rl *rl)
- {
- atomic_inc(&rl->werr_lines);
- }
- void pblk_rl_werr_line_out(struct pblk_rl *rl)
- {
- atomic_dec(&rl->werr_lines);
- }
- void pblk_rl_gc_in(struct pblk_rl *rl, int nr_entries)
- {
- atomic_add(nr_entries, &rl->rb_gc_cnt);
- }
- void pblk_rl_out(struct pblk_rl *rl, int nr_user, int nr_gc)
- {
- atomic_sub(nr_user, &rl->rb_user_cnt);
- atomic_sub(nr_gc, &rl->rb_gc_cnt);
- }
- unsigned long pblk_rl_nr_free_blks(struct pblk_rl *rl)
- {
- return atomic_read(&rl->free_blocks);
- }
- unsigned long pblk_rl_nr_user_free_blks(struct pblk_rl *rl)
- {
- return atomic_read(&rl->free_user_blocks);
- }
- static void __pblk_rl_update_rates(struct pblk_rl *rl,
- unsigned long free_blocks)
- {
- struct pblk *pblk = container_of(rl, struct pblk, rl);
- int max = rl->rb_budget;
- int werr_gc_needed = atomic_read(&rl->werr_lines);
- if (free_blocks >= rl->high) {
- if (werr_gc_needed) {
- /* Allocate a small budget for recovering
- * lines with write errors
- */
- rl->rb_gc_max = 1 << rl->rb_windows_pw;
- rl->rb_user_max = max - rl->rb_gc_max;
- rl->rb_state = PBLK_RL_WERR;
- } else {
- rl->rb_user_max = max;
- rl->rb_gc_max = 0;
- rl->rb_state = PBLK_RL_OFF;
- }
- } else if (free_blocks < rl->high) {
- int shift = rl->high_pw - rl->rb_windows_pw;
- int user_windows = free_blocks >> shift;
- int user_max = user_windows << ilog2(NVM_MAX_VLBA);
- rl->rb_user_max = user_max;
- rl->rb_gc_max = max - user_max;
- if (free_blocks <= rl->rsv_blocks) {
- rl->rb_user_max = 0;
- rl->rb_gc_max = max;
- }
- /* In the worst case, we will need to GC lines in the low list
- * (high valid sector count). If there are lines to GC on high
- * or mid lists, these will be prioritized
- */
- rl->rb_state = PBLK_RL_LOW;
- }
- if (rl->rb_state != PBLK_RL_OFF)
- pblk_gc_should_start(pblk);
- else
- pblk_gc_should_stop(pblk);
- }
- void pblk_rl_update_rates(struct pblk_rl *rl)
- {
- __pblk_rl_update_rates(rl, pblk_rl_nr_user_free_blks(rl));
- }
- void pblk_rl_free_lines_inc(struct pblk_rl *rl, struct pblk_line *line)
- {
- int blk_in_line = atomic_read(&line->blk_in_line);
- int free_blocks;
- atomic_add(blk_in_line, &rl->free_blocks);
- free_blocks = atomic_add_return(blk_in_line, &rl->free_user_blocks);
- __pblk_rl_update_rates(rl, free_blocks);
- }
- void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line,
- bool used)
- {
- int blk_in_line = atomic_read(&line->blk_in_line);
- int free_blocks;
- atomic_sub(blk_in_line, &rl->free_blocks);
- if (used)
- free_blocks = atomic_sub_return(blk_in_line,
- &rl->free_user_blocks);
- else
- free_blocks = atomic_read(&rl->free_user_blocks);
- __pblk_rl_update_rates(rl, free_blocks);
- }
- int pblk_rl_high_thrs(struct pblk_rl *rl)
- {
- return rl->high;
- }
- int pblk_rl_max_io(struct pblk_rl *rl)
- {
- return rl->rb_max_io;
- }
- static void pblk_rl_u_timer(struct timer_list *t)
- {
- struct pblk_rl *rl = from_timer(rl, t, u_timer);
- /* Release user I/O state. Protect from GC */
- smp_store_release(&rl->rb_user_active, 0);
- }
- void pblk_rl_free(struct pblk_rl *rl)
- {
- del_timer(&rl->u_timer);
- }
- void pblk_rl_init(struct pblk_rl *rl, int budget, int threshold)
- {
- struct pblk *pblk = container_of(rl, struct pblk, rl);
- struct nvm_tgt_dev *dev = pblk->dev;
- struct nvm_geo *geo = &dev->geo;
- struct pblk_line_mgmt *l_mg = &pblk->l_mg;
- struct pblk_line_meta *lm = &pblk->lm;
- int sec_meta, blk_meta;
- unsigned int rb_windows;
- /* Consider sectors used for metadata */
- sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;
- blk_meta = DIV_ROUND_UP(sec_meta, geo->clba);
- rl->high = pblk->op_blks - blk_meta - lm->blk_per_line;
- rl->high_pw = get_count_order(rl->high);
- rl->rsv_blocks = pblk_get_min_chks(pblk);
- /* This will always be a power-of-2 */
- rb_windows = budget / NVM_MAX_VLBA;
- rl->rb_windows_pw = get_count_order(rb_windows);
- /* To start with, all buffer is available to user I/O writers */
- rl->rb_budget = budget;
- rl->rb_user_max = budget;
- rl->rb_gc_max = 0;
- rl->rb_state = PBLK_RL_HIGH;
- /* Maximize I/O size and ansure that back threshold is respected */
- if (threshold)
- rl->rb_max_io = budget - pblk->min_write_pgs_data - threshold;
- else
- rl->rb_max_io = budget - pblk->min_write_pgs_data - 1;
- atomic_set(&rl->rb_user_cnt, 0);
- atomic_set(&rl->rb_gc_cnt, 0);
- atomic_set(&rl->rb_space, -1);
- atomic_set(&rl->werr_lines, 0);
- timer_setup(&rl->u_timer, pblk_rl_u_timer, 0);
- rl->rb_user_active = 0;
- rl->rb_gc_active = 0;
- }
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