diff options
| -rw-r--r-- | Documentation/block/queue-sysfs.txt | 4 | ||||
| -rw-r--r-- | block/blk-sysfs.c | 22 | ||||
| -rw-r--r-- | block/blk-wbt.c | 17 | ||||
| -rw-r--r-- | block/blk-wbt.h | 6 |
4 files changed, 37 insertions, 12 deletions
diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt index 14235e72a702..51642159aedb 100644 --- a/Documentation/block/queue-sysfs.txt +++ b/Documentation/block/queue-sysfs.txt @@ -188,7 +188,9 @@ wb_lat_usec (RW) If the device is registered for writeback throttling, then this file shows the target minimum read latency. If this latency is exceeded in a given window of time (see wb_window_usec), then the writeback throttling will start -scaling back writes. +scaling back writes. Writing a value of '0' to this file disables the +feature. Writing a value of '-1' to this file resets the value to the +default setting. Jens Axboe <jens.axboe@oracle.com>, February 2009 diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 1855c6770045..f0ca569e276b 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -42,12 +42,12 @@ queue_var_store(unsigned long *var, const char *page, size_t count) return count; } -static ssize_t queue_var_store64(u64 *var, const char *page) +static ssize_t queue_var_store64(s64 *var, const char *page) { int err; - u64 v; + s64 v; - err = kstrtou64(page, 10, &v); + err = kstrtos64(page, 10, &v); if (err < 0) return err; @@ -421,18 +421,26 @@ static ssize_t queue_wb_lat_show(struct request_queue *q, char *page) static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page, size_t count) { + struct rq_wb *rwb; ssize_t ret; - u64 val; + s64 val; - if (!q->rq_wb) + rwb = q->rq_wb; + if (!rwb) return -EINVAL; ret = queue_var_store64(&val, page); if (ret < 0) return ret; - q->rq_wb->min_lat_nsec = val * 1000ULL; - wbt_update_limits(q->rq_wb); + if (val == -1) + rwb->min_lat_nsec = wbt_default_latency_nsec(q); + else if (val >= 0) + rwb->min_lat_nsec = val * 1000ULL; + else + return -EINVAL; + + wbt_update_limits(rwb); return count; } diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 9f97594e68ce..92df2f7c5af1 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -675,6 +675,18 @@ void wbt_disable(struct rq_wb *rwb) } EXPORT_SYMBOL_GPL(wbt_disable); +u64 wbt_default_latency_nsec(struct request_queue *q) +{ + /* + * We default to 2msec for non-rotational storage, and 75msec + * for rotational storage. + */ + if (blk_queue_nonrot(q)) + return 2000000ULL; + else + return 75000000ULL; +} + int wbt_init(struct request_queue *q) { struct rq_wb *rwb; @@ -711,10 +723,7 @@ int wbt_init(struct request_queue *q) q->rq_wb = rwb; blk_stat_enable(q); - if (blk_queue_nonrot(q)) - rwb->min_lat_nsec = 2000000ULL; - else - rwb->min_lat_nsec = 75000000ULL; + rwb->min_lat_nsec = wbt_default_latency_nsec(q); wbt_set_queue_depth(rwb, blk_queue_depth(q)); wbt_set_write_cache(rwb, test_bit(QUEUE_FLAG_WC, &q->queue_flags)); diff --git a/block/blk-wbt.h b/block/blk-wbt.h index 44dc2173dc1f..9dfc88ad7f30 100644 --- a/block/blk-wbt.h +++ b/block/blk-wbt.h @@ -110,6 +110,8 @@ void wbt_disable(struct rq_wb *); void wbt_set_queue_depth(struct rq_wb *, unsigned int); void wbt_set_write_cache(struct rq_wb *, bool); +u64 wbt_default_latency_nsec(struct request_queue *); + #else static inline void __wbt_done(struct rq_wb *rwb, enum wbt_flags flags) @@ -148,6 +150,10 @@ static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth) static inline void wbt_set_write_cache(struct rq_wb *rwb, bool wc) { } +static inline u64 wbt_default_latency_nsec(struct request_queue *q) +{ + return 0; +} #endif /* CONFIG_BLK_WBT */ |