/*
* 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 << PBLK_MAX_REQ_ADDRS_PW;
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)
{
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 min_blocks = lm->blk_per_line * PBLK_GC_RSV_LINE;
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 = min_blocks;
/* This will always be a power-of-2 */
rb_windows = budget / PBLK_MAX_REQ_ADDRS;
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_max_io = budget >> 1;
rl->rb_gc_max = 0;
rl->rb_state = PBLK_RL_HIGH;
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;
}
