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 ++++++++++++++++++++++++++------------- block/blk-merge.c | 6 +++--- block/blk-settings.c | 2 +- block/blk-tag.c | 8 ++++---- block/elevator.c | 13 ++++++++++--- 5 files changed, 44 insertions(+), 24 deletions(-) (limited to 'block') 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) diff --git a/block/blk-merge.c b/block/blk-merge.c index b5c5c4a9e3f..73b23562af2 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -55,7 +55,7 @@ void blk_recalc_rq_segments(struct request *rq) if (!rq->bio) return; - cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); + cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags); hw_seg_size = seg_size = 0; phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; rq_for_each_segment(bv, rq, iter) { @@ -128,7 +128,7 @@ EXPORT_SYMBOL(blk_recount_segments); static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, struct bio *nxt) { - if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER))) + if (!test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags)) return 0; if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) @@ -175,7 +175,7 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq, int nsegs, cluster; nsegs = 0; - cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); + cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags); /* * for each bio in rq diff --git a/block/blk-settings.c b/block/blk-settings.c index 77b51dc37a3..6089384ab06 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -287,7 +287,7 @@ void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) t->max_segment_size = min(t->max_segment_size, b->max_segment_size); t->hardsect_size = max(t->hardsect_size, b->hardsect_size); if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) - clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags); + queue_flag_clear(QUEUE_FLAG_CLUSTER, t); } EXPORT_SYMBOL(blk_queue_stack_limits); diff --git a/block/blk-tag.c b/block/blk-tag.c index 4780a46ce23..e176ddbe599 100644 --- a/block/blk-tag.c +++ b/block/blk-tag.c @@ -70,7 +70,7 @@ void __blk_queue_free_tags(struct request_queue *q) __blk_free_tags(bqt); q->queue_tags = NULL; - q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED); + queue_flag_clear(QUEUE_FLAG_QUEUED, q); } /** @@ -98,7 +98,7 @@ EXPORT_SYMBOL(blk_free_tags); **/ void blk_queue_free_tags(struct request_queue *q) { - clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); + queue_flag_clear(QUEUE_FLAG_QUEUED, q); } EXPORT_SYMBOL(blk_queue_free_tags); @@ -188,7 +188,7 @@ int blk_queue_init_tags(struct request_queue *q, int depth, rc = blk_queue_resize_tags(q, depth); if (rc) return rc; - set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); + queue_flag_set(QUEUE_FLAG_QUEUED, q); return 0; } else atomic_inc(&tags->refcnt); @@ -197,7 +197,7 @@ int blk_queue_init_tags(struct request_queue *q, int depth, * assign it, all done */ q->queue_tags = tags; - q->queue_flags |= (1 << QUEUE_FLAG_QUEUED); + queue_flag_set(QUEUE_FLAG_QUEUED, q); INIT_LIST_HEAD(&q->tag_busy_list); return 0; fail: diff --git a/block/elevator.c b/block/elevator.c index 88318c38360..e8a90fe2342 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -1070,7 +1070,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) */ spin_lock_irq(q->queue_lock); - set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); elv_drain_elevator(q); @@ -1104,7 +1104,10 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) * finally exit old elevator and turn off BYPASS. */ elevator_exit(old_elevator); - clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + spin_lock_irq(q->queue_lock); + queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); + spin_unlock_irq(q->queue_lock); + return 1; fail_register: @@ -1115,7 +1118,11 @@ fail_register: elevator_exit(e); q->elevator = old_elevator; elv_register_queue(q); - clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); + + spin_lock_irq(q->queue_lock); + queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); + spin_unlock_irq(q->queue_lock); + return 0; } -- cgit v1.2.3