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https://github.com/torvalds/linux
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1d0903d61e
Now that we disable wbt by simply zero out rwb->wb_normal in
wbt_disable_default() when switch elevator to bfq, but it's not safe
because it will become false positive if we change queue depth. If it
become false positive between wbt_wait() and wbt_track() when submit
write request, it will lead to drop rqw->inflight to -1 in wbt_done(),
which will end up trigger IO hung. Fix this issue by introduce a new
state which mean the wbt was disabled.
Fixes: a79050434b ("blk-rq-qos: refactor out common elements of blk-wbt")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20210619093700.920393-2-yi.zhang@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
134 lines
2.8 KiB
C
134 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef WB_THROTTLE_H
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#define WB_THROTTLE_H
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#include <linux/kernel.h>
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#include <linux/atomic.h>
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#include <linux/wait.h>
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#include <linux/timer.h>
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#include <linux/ktime.h>
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#include "blk-stat.h"
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#include "blk-rq-qos.h"
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enum wbt_flags {
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WBT_TRACKED = 1, /* write, tracked for throttling */
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WBT_READ = 2, /* read */
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WBT_KSWAPD = 4, /* write, from kswapd */
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WBT_DISCARD = 8, /* discard */
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WBT_NR_BITS = 4, /* number of bits */
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};
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enum {
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WBT_RWQ_BG = 0,
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WBT_RWQ_KSWAPD,
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WBT_RWQ_DISCARD,
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WBT_NUM_RWQ,
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};
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/*
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* Enable states. Either off, or on by default (done at init time),
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* or on through manual setup in sysfs.
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*/
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enum {
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WBT_STATE_ON_DEFAULT = 1,
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WBT_STATE_ON_MANUAL = 2,
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WBT_STATE_OFF_DEFAULT
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};
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struct rq_wb {
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/*
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* Settings that govern how we throttle
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*/
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unsigned int wb_background; /* background writeback */
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unsigned int wb_normal; /* normal writeback */
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short enable_state; /* WBT_STATE_* */
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/*
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* Number of consecutive periods where we don't have enough
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* information to make a firm scale up/down decision.
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*/
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unsigned int unknown_cnt;
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u64 win_nsec; /* default window size */
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u64 cur_win_nsec; /* current window size */
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struct blk_stat_callback *cb;
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u64 sync_issue;
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void *sync_cookie;
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unsigned int wc;
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unsigned long last_issue; /* last non-throttled issue */
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unsigned long last_comp; /* last non-throttled comp */
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unsigned long min_lat_nsec;
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struct rq_qos rqos;
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struct rq_wait rq_wait[WBT_NUM_RWQ];
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struct rq_depth rq_depth;
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};
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static inline struct rq_wb *RQWB(struct rq_qos *rqos)
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{
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return container_of(rqos, struct rq_wb, rqos);
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}
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static inline unsigned int wbt_inflight(struct rq_wb *rwb)
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{
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unsigned int i, ret = 0;
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for (i = 0; i < WBT_NUM_RWQ; i++)
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ret += atomic_read(&rwb->rq_wait[i].inflight);
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return ret;
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}
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#ifdef CONFIG_BLK_WBT
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int wbt_init(struct request_queue *);
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void wbt_disable_default(struct request_queue *);
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void wbt_enable_default(struct request_queue *);
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u64 wbt_get_min_lat(struct request_queue *q);
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void wbt_set_min_lat(struct request_queue *q, u64 val);
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void wbt_set_write_cache(struct request_queue *, bool);
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u64 wbt_default_latency_nsec(struct request_queue *);
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#else
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static inline void wbt_track(struct request *rq, enum wbt_flags flags)
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{
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}
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static inline int wbt_init(struct request_queue *q)
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{
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return -EINVAL;
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}
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static inline void wbt_disable_default(struct request_queue *q)
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{
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}
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static inline void wbt_enable_default(struct request_queue *q)
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{
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}
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static inline void wbt_set_write_cache(struct request_queue *q, bool wc)
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{
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}
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static inline u64 wbt_get_min_lat(struct request_queue *q)
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{
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return 0;
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}
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static inline void wbt_set_min_lat(struct request_queue *q, u64 val)
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{
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}
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static inline u64 wbt_default_latency_nsec(struct request_queue *q)
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{
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return 0;
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}
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#endif /* CONFIG_BLK_WBT */
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#endif
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