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[PATCH] cfq-iosched: style cleanups and comments

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Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2007-04-26 12:54:48 +02:00 committed by Jens Axboe
parent 67060e3799
commit 498d3aa2b4
1 changed files with 50 additions and 16 deletions
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66
block/cfq-iosched.c
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@ -222,7 +222,7 @@ CFQ_CFQQ_FNS(slice_new);
static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short);
static void cfq_dispatch_insert(request_queue_t *, struct request *);
static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask);
static struct cfq_queue *cfq_get_queue(struct cfq_data *, unsigned int, struct task_struct *, gfp_t);
/*
* scheduler run of queue, if there are requests pending and no one in the
@ -389,6 +389,9 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
}
}
/*
* The below is leftmost cache rbtree addon
*/
static struct rb_node *cfq_rb_first(struct cfq_rb_root *root)
{
if (!root->left)
@ -442,13 +445,18 @@ static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
return ((cfqd->busy_queues - 1) * cfq_prio_slice(cfqd, 1, 0));
}
/*
* The cfqd->service_tree holds all pending cfq_queue's that have
* requests waiting to be processed. It is sorted in the order that
* we will service the queues.
*/
static void cfq_service_tree_add(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
struct rb_node **p = &cfqd->service_tree.rb.rb_node;
struct rb_node *parent = NULL;
unsigned long rb_key;
int left = 1;
int left;
rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
rb_key += cfqq->slice_resid;
@ -464,6 +472,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd,
cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
}
left = 1;
while (*p) {
struct cfq_queue *__cfqq;
struct rb_node **n;
@ -503,17 +512,16 @@ static void cfq_service_tree_add(struct cfq_data *cfqd,
rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
}
/*
* Update cfqq's position in the service tree.
*/
static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
{
struct cfq_data *cfqd = cfqq->cfqd;
/*
* Resorting requires the cfqq to be on the RR list already.
*/
if (!cfq_cfqq_on_rr(cfqq))
return;
cfq_service_tree_add(cfqd, cfqq);
if (cfq_cfqq_on_rr(cfqq))
cfq_service_tree_add(cfqq->cfqd, cfqq);
}
/*
@ -530,6 +538,10 @@ cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
cfq_resort_rr_list(cfqq, 0);
}
/*
* Called when the cfqq no longer has requests pending, remove it from
* the service tree.
*/
static inline void
cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
@ -654,8 +666,7 @@ static void cfq_remove_request(struct request *rq)
}
}
static int
cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
static int cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct request *__rq;
@ -781,6 +792,10 @@ static inline void cfq_slice_expired(struct cfq_data *cfqd, int preempted,
__cfq_slice_expired(cfqd, cfqq, preempted, timed_out);
}
/*
* Get next queue for service. Unless we have a queue preemption,
* we'll simply select the first cfqq in the service tree.
*/
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq = NULL;
@ -792,10 +807,11 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
cfqq = list_entry_cfqq(cfqd->cur_rr.next);
} else if (!RB_EMPTY_ROOT(&cfqd->service_tree.rb)) {
struct rb_node *n = cfq_rb_first(&cfqd->service_tree);
unsigned long end;
cfqq = rb_entry(n, struct cfq_queue, rb_node);
if (cfq_class_idle(cfqq)) {
unsigned long end;
/*
* if we have idle queues and no rt or be queues had
* pending requests, either allow immediate service if
@ -813,6 +829,9 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
return cfqq;
}
/*
* Get and set a new active queue for service.
*/
static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq;
@ -898,6 +917,9 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
}
/*
* Move request from internal lists to the request queue dispatch list.
*/
static void cfq_dispatch_insert(request_queue_t *q, struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
@ -944,7 +966,8 @@ cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
}
/*
* get next queue for service
* Select a queue for service. If we have a current active queue,
* check whether to continue servicing it, or retrieve and set a new one.
*/
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
{
@ -985,6 +1008,10 @@ keep_queue:
return cfqq;
}
/*
* Dispatch some requests from cfqq, moving them to the request queue
* dispatch list.
*/
static int
__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
int max_dispatch)
@ -1059,6 +1086,10 @@ static int cfq_forced_dispatch_cfqqs(struct list_head *list)
return dispatched;
}
/*
* Drain our current requests. Used for barriers and when switching
* io schedulers on-the-fly.
*/
static int cfq_forced_dispatch(struct cfq_data *cfqd)
{
int dispatched = 0;
@ -1224,10 +1255,6 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
}
}
/*
* Called with interrupts disabled
*/
static void cfq_exit_single_io_context(struct cfq_io_context *cic)
{
struct cfq_data *cfqd = cic->key;
@ -1241,6 +1268,10 @@ static void cfq_exit_single_io_context(struct cfq_io_context *cic)
}
}
/*
* The process that ioc belongs to has exited, we need to clean up
* and put the internal structures we have that belongs to that process.
*/
static void cfq_exit_io_context(struct io_context *ioc)
{
struct cfq_io_context *__cic;
@ -1427,6 +1458,9 @@ out:
return cfqq;
}
/*
* We drop cfq io contexts lazily, so we may find a dead one.
*/
static void
cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic)
{