From 80e091d10e8bf7b801d634ea8870b9e907314424 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 28 Nov 2016 09:22:47 -0700 Subject: blk-wbt: allow reset of default latency through sysfs Allow a write of '-1' to reset the default latency target for a given device. This removes knowledge of the different default settings for rotational vs non-rotational from user space. Signed-off-by: Jens Axboe --- block/blk-wbt.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) (limited to 'block/blk-wbt.c') 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)); -- cgit v1.2.3