From 75ad23bc0fcb4f992a5d06982bf0857ab1738e9e Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Tue, 29 Apr 2008 14:48:33 +0200 Subject: block: make queue flags non-atomic We can save some atomic ops in the IO path, if we clearly define the rules of how to modify the queue flags. Signed-off-by: Jens Axboe --- block/blk-core.c | 39 ++++++++++++++++++++++++++------------- 1 file changed, 26 insertions(+), 13 deletions(-) (limited to 'block/blk-core.c') diff --git a/block/blk-core.c b/block/blk-core.c index e447799256d..d2f23ec5ebf 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -198,7 +198,8 @@ void blk_plug_device(struct request_queue *q) if (blk_queue_stopped(q)) return; - if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) { + if (!test_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) { + __set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags); mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG); } @@ -213,9 +214,10 @@ int blk_remove_plug(struct request_queue *q) { WARN_ON(!irqs_disabled()); - if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) + if (!test_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) return 0; + queue_flag_clear(QUEUE_FLAG_PLUGGED, q); del_timer(&q->unplug_timer); return 1; } @@ -311,15 +313,16 @@ void blk_start_queue(struct request_queue *q) { WARN_ON(!irqs_disabled()); - clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); + queue_flag_clear(QUEUE_FLAG_STOPPED, q); /* * one level of recursion is ok and is much faster than kicking * the unplug handling */ - if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { + if (!test_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { + queue_flag_set(QUEUE_FLAG_REENTER, q); q->request_fn(q); - clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); + queue_flag_clear(QUEUE_FLAG_REENTER, q); } else { blk_plug_device(q); kblockd_schedule_work(&q->unplug_work); @@ -344,7 +347,7 @@ EXPORT_SYMBOL(blk_start_queue); void blk_stop_queue(struct request_queue *q) { blk_remove_plug(q); - set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); + queue_flag_set(QUEUE_FLAG_STOPPED, q); } EXPORT_SYMBOL(blk_stop_queue); @@ -373,11 +376,8 @@ EXPORT_SYMBOL(blk_sync_queue); * blk_run_queue - run a single device queue * @q: The queue to run */ -void blk_run_queue(struct request_queue *q) +void __blk_run_queue(struct request_queue *q) { - unsigned long flags; - - spin_lock_irqsave(q->queue_lock, flags); blk_remove_plug(q); /* @@ -385,15 +385,28 @@ void blk_run_queue(struct request_queue *q) * handling reinvoke the handler shortly if we already got there. */ if (!elv_queue_empty(q)) { - if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { + if (!test_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { + queue_flag_set(QUEUE_FLAG_REENTER, q); q->request_fn(q); - clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); + queue_flag_clear(QUEUE_FLAG_REENTER, q); } else { blk_plug_device(q); kblockd_schedule_work(&q->unplug_work); } } +} +EXPORT_SYMBOL(__blk_run_queue); +/** + * blk_run_queue - run a single device queue + * @q: The queue to run + */ +void blk_run_queue(struct request_queue *q) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + __blk_run_queue(q); spin_unlock_irqrestore(q->queue_lock, flags); } EXPORT_SYMBOL(blk_run_queue); @@ -406,7 +419,7 @@ void blk_put_queue(struct request_queue *q) void blk_cleanup_queue(struct request_queue *q) { mutex_lock(&q->sysfs_lock); - set_bit(QUEUE_FLAG_DEAD, &q->queue_flags); + queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); mutex_unlock(&q->sysfs_lock); if (q->elevator) -- cgit v1.2.3