From 3c5820c743479285ce2678fd3c12b1fd39fe998f Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Fri, 11 Sep 2009 21:54:52 +0200 Subject: block: Optimal I/O limit wrapper Implement blk_limits_io_opt() and make blk_queue_io_opt() a wrapper around it. DM needs this to avoid poking at the queue_limits directly. Signed-off-by: Martin K. Petersen Signed-off-by: Mike Snitzer Signed-off-by: Jens Axboe --- block/blk-settings.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) (limited to 'block/blk-settings.c') diff --git a/block/blk-settings.c b/block/blk-settings.c index 476d8706507..83413ff8373 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -427,6 +427,25 @@ void blk_queue_io_min(struct request_queue *q, unsigned int min) } EXPORT_SYMBOL(blk_queue_io_min); +/** + * blk_limits_io_opt - set optimal request size for a device + * @limits: the queue limits + * @opt: smallest I/O size in bytes + * + * Description: + * Storage devices may report an optimal I/O size, which is the + * device's preferred unit for sustained I/O. This is rarely reported + * for disk drives. For RAID arrays it is usually the stripe width or + * the internal track size. A properly aligned multiple of + * optimal_io_size is the preferred request size for workloads where + * sustained throughput is desired. + */ +void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) +{ + limits->io_opt = opt; +} +EXPORT_SYMBOL(blk_limits_io_opt); + /** * blk_queue_io_opt - set optimal request size for the queue * @q: the request queue for the device @@ -442,7 +461,7 @@ EXPORT_SYMBOL(blk_queue_io_min); */ void blk_queue_io_opt(struct request_queue *q, unsigned int opt) { - q->limits.io_opt = opt; + blk_limits_io_opt(&q->limits, opt); } EXPORT_SYMBOL(blk_queue_io_opt); -- cgit v1.2.3-70-g09d2