[PATCH] cfq-iosched: cleanups, fixes, dead code removal
A collection of little fixes and cleanups:
- We don't use the 'queued' sysfs exported attribute, since the
may_queue() logic was rewritten. So kill it.
- Remove dead defines.
- cfq_set_active_queue() can be rewritten cleaner with else if conditions.
- Several places had cfq_exit_cfqq() like logic, abstract that out and
use that.
- Annotate the cfqq kmem_cache_alloc() so the allocator knows that this
is a repeat allocation if it fails with __GFP_WAIT set. Allows the
allocator to start freeing some memory, if needed. CFQ already loops for
this condition, so might as well pass the hint down.
- Remove cfqd->rq_starved logic. It's not needed anymore after we dropped
the crq allocation in cfq_set_request().
- Remove uneeded parameter passing.
Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 2ac35aa..ec24284 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -17,7 +17,6 @@
* tunables
*/
static const int cfq_quantum = 4; /* max queue in one round of service */
-static const int cfq_queued = 8; /* minimum rq allocate limit per-queue*/
static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
static const int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */
static const int cfq_back_penalty = 2; /* penalty of a backwards seek */
@@ -54,7 +53,6 @@
#define CFQ_PRIO_LISTS IOPRIO_BE_NR
#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
-#define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE)
#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
#define ASYNC (0)
@@ -99,9 +97,6 @@
int hw_tag;
/*
- * schedule slice state info
- */
- /*
* idle window management
*/
struct timer_list idle_slice_timer;
@@ -117,13 +112,10 @@
sector_t last_sector;
unsigned long last_end_request;
- unsigned int rq_starved;
-
/*
* tunables, see top of file
*/
unsigned int cfq_quantum;
- unsigned int cfq_queued;
unsigned int cfq_fifo_expire[2];
unsigned int cfq_back_penalty;
unsigned int cfq_back_max;
@@ -484,12 +476,14 @@
{
struct task_struct *tsk = current;
pid_t key = cfq_queue_pid(tsk, bio_data_dir(bio));
- sector_t sector = bio->bi_sector + bio_sectors(bio);
struct cfq_queue *cfqq;
cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio);
- if (cfqq)
+ if (cfqq) {
+ sector_t sector = bio->bi_sector + bio_sectors(bio);
+
return elv_rb_find(&cfqq->sort_list, sector);
+ }
return NULL;
}
@@ -699,26 +693,25 @@
{
struct cfq_queue *cfqq = NULL;
- /*
- * if current list is non-empty, grab first entry. if it is empty,
- * get next prio level and grab first entry then if any are spliced
- */
- if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1)
+ if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) {
+ /*
+ * if current list is non-empty, grab first entry. if it is
+ * empty, get next prio level and grab first entry then if any
+ * are spliced
+ */
cfqq = list_entry_cfqq(cfqd->cur_rr.next);
-
- /*
- * If no new queues are available, check if the busy list has some
- * before falling back to idle io.
- */
- if (!cfqq && !list_empty(&cfqd->busy_rr))
+ } else if (!list_empty(&cfqd->busy_rr)) {
+ /*
+ * If no new queues are available, check if the busy list has
+ * some before falling back to idle io.
+ */
cfqq = list_entry_cfqq(cfqd->busy_rr.next);
-
- /*
- * if we have idle queues and no rt or be queues had pending
- * requests, either allow immediate service if the grace period
- * has passed or arm the idle grace timer
- */
- if (!cfqq && !list_empty(&cfqd->idle_rr)) {
+ } else if (!list_empty(&cfqd->idle_rr)) {
+ /*
+ * if we have idle queues and no rt or be queues had pending
+ * requests, either allow immediate service if the grace period
+ * has passed or arm the idle grace timer
+ */
unsigned long end = cfqd->last_end_request + CFQ_IDLE_GRACE;
if (time_after_eq(jiffies, end))
@@ -793,18 +786,19 @@
{
struct cfq_data *cfqd = cfqq->cfqd;
struct request *rq;
+ int fifo;
if (cfq_cfqq_fifo_expire(cfqq))
return NULL;
+ if (list_empty(&cfqq->fifo))
+ return NULL;
- if (!list_empty(&cfqq->fifo)) {
- int fifo = cfq_cfqq_class_sync(cfqq);
+ fifo = cfq_cfqq_class_sync(cfqq);
+ rq = rq_entry_fifo(cfqq->fifo.next);
- rq = rq_entry_fifo(cfqq->fifo.next);
- if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) {
- cfq_mark_cfqq_fifo_expire(cfqq);
- return rq;
- }
+ if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) {
+ cfq_mark_cfqq_fifo_expire(cfqq);
+ return rq;
}
return NULL;
@@ -1096,40 +1090,48 @@
cfq_free_io_context(ioc);
}
+static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ if (unlikely(cfqq == cfqd->active_queue))
+ __cfq_slice_expired(cfqd, cfqq, 0);
+
+ cfq_put_queue(cfqq);
+}
+
+static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
+ struct cfq_io_context *cic)
+{
+ if (cic->cfqq[ASYNC]) {
+ cfq_exit_cfqq(cfqd, cic->cfqq[ASYNC]);
+ cic->cfqq[ASYNC] = NULL;
+ }
+
+ if (cic->cfqq[SYNC]) {
+ cfq_exit_cfqq(cfqd, cic->cfqq[SYNC]);
+ cic->cfqq[SYNC] = NULL;
+ }
+
+ cic->key = NULL;
+ list_del_init(&cic->queue_list);
+}
+
+
/*
* Called with interrupts disabled
*/
static void cfq_exit_single_io_context(struct cfq_io_context *cic)
{
struct cfq_data *cfqd = cic->key;
- request_queue_t *q;
-
- if (!cfqd)
- return;
-
- q = cfqd->queue;
WARN_ON(!irqs_disabled());
- spin_lock(q->queue_lock);
+ if (cfqd) {
+ request_queue_t *q = cfqd->queue;
- if (cic->cfqq[ASYNC]) {
- if (unlikely(cic->cfqq[ASYNC] == cfqd->active_queue))
- __cfq_slice_expired(cfqd, cic->cfqq[ASYNC], 0);
- cfq_put_queue(cic->cfqq[ASYNC]);
- cic->cfqq[ASYNC] = NULL;
+ spin_lock(q->queue_lock);
+ __cfq_exit_single_io_context(cfqd, cic);
+ spin_unlock(q->queue_lock);
}
-
- if (cic->cfqq[SYNC]) {
- if (unlikely(cic->cfqq[SYNC] == cfqd->active_queue))
- __cfq_slice_expired(cfqd, cic->cfqq[SYNC], 0);
- cfq_put_queue(cic->cfqq[SYNC]);
- cic->cfqq[SYNC] = NULL;
- }
-
- cic->key = NULL;
- list_del_init(&cic->queue_list);
- spin_unlock(q->queue_lock);
}
static void cfq_exit_io_context(struct io_context *ioc)
@@ -1286,8 +1288,14 @@
cfqq = new_cfqq;
new_cfqq = NULL;
} else if (gfp_mask & __GFP_WAIT) {
+ /*
+ * Inform the allocator of the fact that we will
+ * just repeat this allocation if it fails, to allow
+ * the allocator to do whatever it needs to attempt to
+ * free memory.
+ */
spin_unlock_irq(cfqd->queue->queue_lock);
- new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask);
+ new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask|__GFP_NOFAIL);
spin_lock_irq(cfqd->queue->queue_lock);
goto retry;
} else {
@@ -1739,9 +1747,7 @@
cfq_resort_rr_list(cfqq, 0);
}
-static inline int
-__cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq,
- struct task_struct *task, int rw)
+static inline int __cfq_may_queue(struct cfq_queue *cfqq)
{
if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
!cfq_cfqq_must_alloc_slice(cfqq)) {
@@ -1769,27 +1775,12 @@
cfq_init_prio_data(cfqq);
cfq_prio_boost(cfqq);
- return __cfq_may_queue(cfqd, cfqq, tsk, rw);
+ return __cfq_may_queue(cfqq);
}
return ELV_MQUEUE_MAY;
}
-static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq)
-{
- struct cfq_data *cfqd = q->elevator->elevator_data;
-
- if (unlikely(cfqd->rq_starved)) {
- struct request_list *rl = &q->rq;
-
- smp_mb();
- if (waitqueue_active(&rl->wait[READ]))
- wake_up(&rl->wait[READ]);
- if (waitqueue_active(&rl->wait[WRITE]))
- wake_up(&rl->wait[WRITE]);
- }
-}
-
/*
* queue lock held here
*/
@@ -1808,7 +1799,6 @@
rq->elevator_private = NULL;
rq->elevator_private2 = NULL;
- cfq_check_waiters(q, cfqq);
cfq_put_queue(cfqq);
}
}
@@ -1848,7 +1838,6 @@
cfqq->allocated[rw]++;
cfq_clear_cfqq_must_alloc(cfqq);
- cfqd->rq_starved = 0;
atomic_inc(&cfqq->ref);
spin_unlock_irqrestore(q->queue_lock, flags);
@@ -1860,12 +1849,7 @@
queue_fail:
if (cic)
put_io_context(cic->ioc);
- /*
- * mark us rq allocation starved. we need to kickstart the process
- * ourselves if there are no pending requests that can do it for us.
- * that would be an extremely rare OOM situation
- */
- cfqd->rq_starved = 1;
+
cfq_schedule_dispatch(cfqd);
spin_unlock_irqrestore(q->queue_lock, flags);
return 1;
@@ -1874,25 +1858,9 @@
static void cfq_kick_queue(void *data)
{
request_queue_t *q = data;
- struct cfq_data *cfqd = q->elevator->elevator_data;
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
-
- if (cfqd->rq_starved) {
- struct request_list *rl = &q->rq;
-
- /*
- * we aren't guaranteed to get a request after this, but we
- * have to be opportunistic
- */
- smp_mb();
- if (waitqueue_active(&rl->wait[READ]))
- wake_up(&rl->wait[READ]);
- if (waitqueue_active(&rl->wait[WRITE]))
- wake_up(&rl->wait[WRITE]);
- }
-
blk_remove_plug(q);
q->request_fn(q);
spin_unlock_irqrestore(q->queue_lock, flags);
@@ -1987,16 +1955,8 @@
struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
struct cfq_io_context,
queue_list);
- if (cic->cfqq[ASYNC]) {
- cfq_put_queue(cic->cfqq[ASYNC]);
- cic->cfqq[ASYNC] = NULL;
- }
- if (cic->cfqq[SYNC]) {
- cfq_put_queue(cic->cfqq[SYNC]);
- cic->cfqq[SYNC] = NULL;
- }
- cic->key = NULL;
- list_del_init(&cic->queue_list);
+
+ __cfq_exit_single_io_context(cfqd, cic);
}
spin_unlock_irq(q->queue_lock);
@@ -2047,7 +2007,6 @@
INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q);
- cfqd->cfq_queued = cfq_queued;
cfqd->cfq_quantum = cfq_quantum;
cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
@@ -2119,7 +2078,6 @@
return cfq_var_show(__data, (page)); \
}
SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
-SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0);
SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
@@ -2147,7 +2105,6 @@
return ret; \
}
STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
-STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0);
STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
@@ -2163,7 +2120,6 @@
static struct elv_fs_entry cfq_attrs[] = {
CFQ_ATTR(quantum),
- CFQ_ATTR(queued),
CFQ_ATTR(fifo_expire_sync),
CFQ_ATTR(fifo_expire_async),
CFQ_ATTR(back_seek_max),