Throttle discards like we would any background write. Discards should be background activity, so if they are impacting foreground IO, then we will throttle them down. Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> --- block/blk-stat.h | 6 +++--- block/blk-wbt.c | 43 ++++++++++++++++++++++++++----------------- block/blk-wbt.h | 4 +++- 3 files changed, 32 insertions(+), 21 deletions(-) diff --git a/block/blk-stat.h b/block/blk-stat.h index 2dd36347252a..c22049a8125e 100644 --- a/block/blk-stat.h +++ b/block/blk-stat.h @@ -10,11 +10,11 @@ /* * from upper: - * 3 bits: reserved for other usage + * 4 bits: reserved for other usage * 12 bits: size - * 49 bits: time + * 48 bits: time */ -#define BLK_STAT_RES_BITS 3 +#define BLK_STAT_RES_BITS 4 #define BLK_STAT_SIZE_BITS 12 #define BLK_STAT_RES_SHIFT (64 - BLK_STAT_RES_BITS) #define BLK_STAT_SIZE_SHIFT (BLK_STAT_RES_SHIFT - BLK_STAT_SIZE_BITS) diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 25d202345965..a7a724580033 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -106,6 +106,8 @@ static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb, { if (wb_acct & WBT_KSWAPD) return &rwb->rq_wait[WBT_RWQ_KSWAPD]; + else if (wb_acct & WBT_DISCARD) + return &rwb->rq_wait[WBT_RWQ_DISCARD]; return &rwb->rq_wait[WBT_RWQ_BG]; } @@ -143,10 +145,13 @@ void __wbt_done(struct rq_wb *rwb, enum wbt_flags wb_acct) } /* - * If the device does write back caching, drop further down - * before we wake people up. + * For discards, our limit is always the background. For writes, if + * the device does write back caching, drop further down before we + * wake people up. */ - if (rwb->wc && !wb_recent_wait(rwb)) + if (wb_acct & WBT_DISCARD) + limit = rwb->wb_background; + else if (rwb->wc && !wb_recent_wait(rwb)) limit = 0; else limit = rwb->wb_normal; @@ -483,6 +488,9 @@ static inline unsigned int get_limit(struct rq_wb *rwb, unsigned long rw) { unsigned int limit; + if ((rw & REQ_OP_MASK) == REQ_OP_DISCARD) + return rwb->wb_background; + /* * At this point we know it's a buffered write. If this is * kswapd trying to free memory, or REQ_SYNC is set, then @@ -564,21 +572,20 @@ static void __wbt_wait(struct rq_wb *rwb, enum wbt_flags wb_acct, static inline bool wbt_should_throttle(struct rq_wb *rwb, struct bio *bio) { - const int op = bio_op(bio); - - /* - * If not a WRITE, do nothing - */ - if (op != REQ_OP_WRITE) - return false; - - /* - * Don't throttle WRITE_ODIRECT - */ - if ((bio->bi_opf & (REQ_SYNC | REQ_IDLE)) == (REQ_SYNC | REQ_IDLE)) + switch (bio_op(bio)) { + case REQ_OP_WRITE: + /* + * Don't throttle WRITE_ODIRECT + */ + if ((bio->bi_opf & (REQ_SYNC | REQ_IDLE)) == + (REQ_SYNC | REQ_IDLE)) + return false; + /* fallthrough */ + case REQ_OP_DISCARD: + return true; + default: return false; - - return true; + } } /* @@ -605,6 +612,8 @@ enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio, spinlock_t *lock) if (current_is_kswapd()) ret |= WBT_KSWAPD; + if (bio_op(bio) == REQ_OP_DISCARD) + ret |= WBT_DISCARD; __wbt_wait(rwb, ret, bio->bi_opf, lock); diff --git a/block/blk-wbt.h b/block/blk-wbt.h index 8038b4a0d4ef..d6a125e49db5 100644 --- a/block/blk-wbt.h +++ b/block/blk-wbt.h @@ -14,13 +14,15 @@ enum wbt_flags { WBT_TRACKED = 1, /* write, tracked for throttling */ WBT_READ = 2, /* read */ WBT_KSWAPD = 4, /* write, from kswapd */ + WBT_DISCARD = 8, /* discard */ - WBT_NR_BITS = 3, /* number of bits */ + WBT_NR_BITS = 4, /* number of bits */ }; enum { WBT_RWQ_BG = 0, WBT_RWQ_KSWAPD, + WBT_RWQ_DISCARD, WBT_NUM_RWQ, }; -- 2.7.4