static int cfq_slice_async = HZ / 25;
static const int cfq_slice_async_rq = 2;
static int cfq_slice_idle = HZ / 125;
+static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
+static const int cfq_hist_divisor = 4;
/*
* offset from end of service tree
*/
#define CFQ_MIN_TT (2)
+/*
+ * Allow merged cfqqs to perform this amount of seeky I/O before
+ * deciding to break the queues up again.
+ */
+#define CFQQ_COOP_TOUT (HZ)
+
#define CFQ_SLICE_SCALE (5)
#define CFQ_HW_QUEUE_MIN (5)
struct cfq_rb_root {
struct rb_root rb;
struct rb_node *left;
+ unsigned count;
};
-#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, }
+#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, }
/*
* Per process-grouping structure
u64 seek_total;
sector_t seek_mean;
sector_t last_request_pos;
+ unsigned long seeky_start;
pid_t pid;
+
+ struct cfq_rb_root *service_tree;
+ struct cfq_queue *new_cfqq;
};
/*
+ * First index in the service_trees.
+ * IDLE is handled separately, so it has negative index
+ */
+enum wl_prio_t {
+ IDLE_WORKLOAD = -1,
+ BE_WORKLOAD = 0,
+ RT_WORKLOAD = 1
+};
+
+/*
+ * Second index in the service_trees.
+ */
+enum wl_type_t {
+ ASYNC_WORKLOAD = 0,
+ SYNC_NOIDLE_WORKLOAD = 1,
+ SYNC_WORKLOAD = 2
+};
+
+
+/*
* Per block device queue structure
*/
struct cfq_data {
struct request_queue *queue;
/*
- * rr list of queues with requests and the count of them
+ * rr lists of queues with requests, onle rr for each priority class.
+ * Counts are embedded in the cfq_rb_root
*/
- struct cfq_rb_root service_tree;
+ struct cfq_rb_root service_trees[2][3];
+ struct cfq_rb_root service_tree_idle;
+ /*
+ * The priority currently being served
+ */
+ enum wl_prio_t serving_prio;
+ enum wl_type_t serving_type;
+ unsigned long workload_expires;
/*
* Each priority tree is sorted by next_request position. These
struct rb_root prio_trees[CFQ_PRIO_LISTS];
unsigned int busy_queues;
+ unsigned int busy_queues_avg[2];
int rq_in_driver[2];
int sync_flight;
unsigned long last_end_sync_rq;
};
+static struct cfq_rb_root *service_tree_for(enum wl_prio_t prio,
+ enum wl_type_t type,
+ struct cfq_data *cfqd)
+{
+ if (prio == IDLE_WORKLOAD)
+ return &cfqd->service_tree_idle;
+
+ return &cfqd->service_trees[prio][type];
+}
+
enum cfqq_state_flags {
CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
CFQ_CFQQ_FLAG_sync, /* synchronous queue */
- CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
+ CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
};
#define CFQ_CFQQ_FNS(name) \
#define cfq_log(cfqd, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
+static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
+{
+ if (cfq_class_idle(cfqq))
+ return IDLE_WORKLOAD;
+ if (cfq_class_rt(cfqq))
+ return RT_WORKLOAD;
+ return BE_WORKLOAD;
+}
+
+
+static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
+{
+ if (!cfq_cfqq_sync(cfqq))
+ return ASYNC_WORKLOAD;
+ if (!cfq_cfqq_idle_window(cfqq))
+ return SYNC_NOIDLE_WORKLOAD;
+ return SYNC_WORKLOAD;
+}
+
+static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd)
+{
+ if (wl == IDLE_WORKLOAD)
+ return cfqd->service_tree_idle.count;
+
+ return cfqd->service_trees[wl][ASYNC_WORKLOAD].count
+ + cfqd->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
+ + cfqd->service_trees[wl][SYNC_WORKLOAD].count;
+}
+
static void cfq_dispatch_insert(struct request_queue *, struct request *);
static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
struct io_context *, gfp_t);
return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
}
+/*
+ * get averaged number of queues of RT/BE priority.
+ * average is updated, with a formula that gives more weight to higher numbers,
+ * to quickly follows sudden increases and decrease slowly
+ */
+
+static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt)
+{
+ unsigned min_q, max_q;
+ unsigned mult = cfq_hist_divisor - 1;
+ unsigned round = cfq_hist_divisor / 2;
+ unsigned busy = cfq_busy_queues_wl(rt, cfqd);
+
+ min_q = min(cfqd->busy_queues_avg[rt], busy);
+ max_q = max(cfqd->busy_queues_avg[rt], busy);
+ cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
+ cfq_hist_divisor;
+ return cfqd->busy_queues_avg[rt];
+}
+
static inline void
cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
- cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
+ unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
+ if (cfqd->cfq_latency) {
+ /* interested queues (we consider only the ones with the same
+ * priority class) */
+ unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq));
+ unsigned sync_slice = cfqd->cfq_slice[1];
+ unsigned expect_latency = sync_slice * iq;
+ if (expect_latency > cfq_target_latency) {
+ unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
+ /* scale low_slice according to IO priority
+ * and sync vs async */
+ unsigned low_slice =
+ min(slice, base_low_slice * slice / sync_slice);
+ /* the adapted slice value is scaled to fit all iqs
+ * into the target latency */
+ slice = max(slice * cfq_target_latency / expect_latency,
+ low_slice);
+ }
+ }
+ cfqq->slice_end = jiffies + slice;
cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
}
if (root->left == n)
root->left = NULL;
rb_erase_init(n, &root->rb);
+ --root->count;
}
/*
}
/*
- * The cfqd->service_tree holds all pending cfq_queue's that have
+ * The cfqd->service_trees 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.
*/
struct rb_node **p, *parent;
struct cfq_queue *__cfqq;
unsigned long rb_key;
+ struct cfq_rb_root *service_tree;
int left;
+ service_tree = service_tree_for(cfqq_prio(cfqq), cfqq_type(cfqq), cfqd);
if (cfq_class_idle(cfqq)) {
rb_key = CFQ_IDLE_DELAY;
- parent = rb_last(&cfqd->service_tree.rb);
+ parent = rb_last(&service_tree->rb);
if (parent && parent != &cfqq->rb_node) {
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
rb_key += __cfqq->rb_key;
cfqq->slice_resid = 0;
} else {
rb_key = -HZ;
- __cfqq = cfq_rb_first(&cfqd->service_tree);
+ __cfqq = cfq_rb_first(service_tree);
rb_key += __cfqq ? __cfqq->rb_key : jiffies;
}
/*
* same position, nothing more to do
*/
- if (rb_key == cfqq->rb_key)
+ if (rb_key == cfqq->rb_key &&
+ cfqq->service_tree == service_tree)
return;
- cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
+ cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
+ cfqq->service_tree = NULL;
}
left = 1;
parent = NULL;
- p = &cfqd->service_tree.rb.rb_node;
+ cfqq->service_tree = service_tree;
+ p = &service_tree->rb.rb_node;
while (*p) {
struct rb_node **n;
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
/*
- * sort RT queues first, we always want to give
- * preference to them. IDLE queues goes to the back.
- * after that, sort on the next service time.
+ * sort by key, that represents service time.
*/
- if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
- n = &(*p)->rb_left;
- else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
- n = &(*p)->rb_right;
- else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
- n = &(*p)->rb_left;
- else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
- n = &(*p)->rb_right;
- else if (time_before(rb_key, __cfqq->rb_key))
+ if (time_before(rb_key, __cfqq->rb_key))
n = &(*p)->rb_left;
- else
+ else {
n = &(*p)->rb_right;
-
- if (n == &(*p)->rb_right)
left = 0;
+ }
p = n;
}
if (left)
- cfqd->service_tree.left = &cfqq->rb_node;
+ service_tree->left = &cfqq->rb_node;
cfqq->rb_key = rb_key;
rb_link_node(&cfqq->rb_node, parent, p);
- rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
+ rb_insert_color(&cfqq->rb_node, &service_tree->rb);
+ service_tree->count++;
}
static struct cfq_queue *
BUG_ON(!cfq_cfqq_on_rr(cfqq));
cfq_clear_cfqq_on_rr(cfqq);
- if (!RB_EMPTY_NODE(&cfqq->rb_node))
- cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
+ if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
+ cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
+ cfqq->service_tree = NULL;
+ }
if (cfqq->p_root) {
rb_erase(&cfqq->p_node, cfqq->p_root);
cfqq->p_root = NULL;
*/
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
{
- if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
- return NULL;
+ struct cfq_rb_root *service_tree =
+ service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd);
- return cfq_rb_first(&cfqd->service_tree);
+ if (RB_EMPTY_ROOT(&service_tree->rb))
+ return NULL;
+ return cfq_rb_first(service_tree);
}
/*
static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
- if (!cfqq) {
+ if (!cfqq)
cfqq = cfq_get_next_queue(cfqd);
- if (cfqq)
- cfq_clear_cfqq_coop(cfqq);
- }
__cfq_set_active_queue(cfqd, cfqq);
return cfqq;
* assumption.
*/
static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
- struct cfq_queue *cur_cfqq,
- bool probe)
+ struct cfq_queue *cur_cfqq)
{
struct cfq_queue *cfqq;
+ if (!cfq_cfqq_sync(cur_cfqq))
+ return NULL;
+ if (CFQQ_SEEKY(cur_cfqq))
+ return NULL;
+
/*
* We should notice if some of the queues are cooperating, eg
* working closely on the same area of the disk. In that case,
if (!cfqq)
return NULL;
- if (cfq_cfqq_coop(cfqq))
+ /*
+ * It only makes sense to merge sync queues.
+ */
+ if (!cfq_cfqq_sync(cfqq))
+ return NULL;
+ if (CFQQ_SEEKY(cfqq))
+ return NULL;
+
+ /*
+ * Do not merge queues of different priority classes
+ */
+ if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
return NULL;
- if (!probe)
- cfq_mark_cfqq_coop(cfqq);
return cfqq;
}
+/*
+ * Determine whether we should enforce idle window for this queue.
+ */
+
+static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ enum wl_prio_t prio = cfqq_prio(cfqq);
+ struct cfq_rb_root *service_tree = cfqq->service_tree;
+
+ /* We never do for idle class queues. */
+ if (prio == IDLE_WORKLOAD)
+ return false;
+
+ /* We do for queues that were marked with idle window flag. */
+ if (cfq_cfqq_idle_window(cfqq))
+ return true;
+
+ /*
+ * Otherwise, we do only if they are the last ones
+ * in their service tree.
+ */
+ if (!service_tree)
+ service_tree = service_tree_for(prio, cfqq_type(cfqq), cfqd);
+
+ if (service_tree->count == 0)
+ return true;
+
+ return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq);
+}
+
static void cfq_arm_slice_timer(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq = cfqd->active_queue;
/*
* idle is disabled, either manually or by past process history
*/
- if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
+ if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
return;
/*
cfq_mark_cfqq_wait_request(cfqq);
- /*
- * we don't want to idle for seeks, but we do want to allow
- * fair distribution of slice time for a process doing back-to-back
- * seeks. so allow a little bit of time for him to submit a new rq
- */
sl = cfqd->cfq_slice_idle;
- if (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq))
+ /* are we servicing noidle tree, and there are more queues?
+ * non-rotational or NCQ: no idle
+ * non-NCQ rotational : very small idle, to allow
+ * fair distribution of slice time for a process doing back-to-back
+ * seeks.
+ */
+ if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
+ service_tree_for(cfqd->serving_prio, SYNC_NOIDLE_WORKLOAD, cfqd)
+ ->count > 0) {
+ if (blk_queue_nonrot(cfqd->queue) || cfqd->hw_tag)
+ return;
sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
+ }
mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
}
/*
+ * Must be called with the queue_lock held.
+ */
+static int cfqq_process_refs(struct cfq_queue *cfqq)
+{
+ int process_refs, io_refs;
+
+ io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
+ process_refs = atomic_read(&cfqq->ref) - io_refs;
+ BUG_ON(process_refs < 0);
+ return process_refs;
+}
+
+static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
+{
+ int process_refs, new_process_refs;
+ struct cfq_queue *__cfqq;
+
+ /* Avoid a circular list and skip interim queue merges */
+ while ((__cfqq = new_cfqq->new_cfqq)) {
+ if (__cfqq == cfqq)
+ return;
+ new_cfqq = __cfqq;
+ }
+
+ process_refs = cfqq_process_refs(cfqq);
+ /*
+ * If the process for the cfqq has gone away, there is no
+ * sense in merging the queues.
+ */
+ if (process_refs == 0)
+ return;
+
+ /*
+ * Merge in the direction of the lesser amount of work.
+ */
+ new_process_refs = cfqq_process_refs(new_cfqq);
+ if (new_process_refs >= process_refs) {
+ cfqq->new_cfqq = new_cfqq;
+ atomic_add(process_refs, &new_cfqq->ref);
+ } else {
+ new_cfqq->new_cfqq = cfqq;
+ atomic_add(new_process_refs, &cfqq->ref);
+ }
+}
+
+static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, enum wl_prio_t prio,
+ bool prio_changed)
+{
+ struct cfq_queue *queue;
+ int i;
+ bool key_valid = false;
+ unsigned long lowest_key = 0;
+ enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
+
+ if (prio_changed) {
+ /*
+ * When priorities switched, we prefer starting
+ * from SYNC_NOIDLE (first choice), or just SYNC
+ * over ASYNC
+ */
+ if (service_tree_for(prio, cur_best, cfqd)->count)
+ return cur_best;
+ cur_best = SYNC_WORKLOAD;
+ if (service_tree_for(prio, cur_best, cfqd)->count)
+ return cur_best;
+
+ return ASYNC_WORKLOAD;
+ }
+
+ for (i = 0; i < 3; ++i) {
+ /* otherwise, select the one with lowest rb_key */
+ queue = cfq_rb_first(service_tree_for(prio, i, cfqd));
+ if (queue &&
+ (!key_valid || time_before(queue->rb_key, lowest_key))) {
+ lowest_key = queue->rb_key;
+ cur_best = i;
+ key_valid = true;
+ }
+ }
+
+ return cur_best;
+}
+
+static void choose_service_tree(struct cfq_data *cfqd)
+{
+ enum wl_prio_t previous_prio = cfqd->serving_prio;
+ bool prio_changed;
+ unsigned slice;
+ unsigned count;
+
+ /* Choose next priority. RT > BE > IDLE */
+ if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd))
+ cfqd->serving_prio = RT_WORKLOAD;
+ else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd))
+ cfqd->serving_prio = BE_WORKLOAD;
+ else {
+ cfqd->serving_prio = IDLE_WORKLOAD;
+ cfqd->workload_expires = jiffies + 1;
+ return;
+ }
+
+ /*
+ * For RT and BE, we have to choose also the type
+ * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
+ * expiration time
+ */
+ prio_changed = (cfqd->serving_prio != previous_prio);
+ count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd)
+ ->count;
+
+ /*
+ * If priority didn't change, check workload expiration,
+ * and that we still have other queues ready
+ */
+ if (!prio_changed && count &&
+ !time_after(jiffies, cfqd->workload_expires))
+ return;
+
+ /* otherwise select new workload type */
+ cfqd->serving_type =
+ cfq_choose_wl(cfqd, cfqd->serving_prio, prio_changed);
+ count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd)
+ ->count;
+
+ /*
+ * the workload slice is computed as a fraction of target latency
+ * proportional to the number of queues in that workload, over
+ * all the queues in the same priority class
+ */
+ slice = cfq_target_latency * count /
+ max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio],
+ cfq_busy_queues_wl(cfqd->serving_prio, cfqd));
+
+ if (cfqd->serving_type == ASYNC_WORKLOAD)
+ /* async workload slice is scaled down according to
+ * the sync/async slice ratio. */
+ slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
+ else
+ /* sync workload slice is at least 2 * cfq_slice_idle */
+ slice = max(slice, 2 * cfqd->cfq_slice_idle);
+
+ slice = max_t(unsigned, slice, CFQ_MIN_TT);
+ cfqd->workload_expires = jiffies + slice;
+}
+
+/*
* 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.
*/
* If another queue has a request waiting within our mean seek
* distance, let it run. The expire code will check for close
* cooperators and put the close queue at the front of the service
- * tree.
+ * tree. If possible, merge the expiring queue with the new cfqq.
*/
- new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
- if (new_cfqq)
+ new_cfqq = cfq_close_cooperator(cfqd, cfqq);
+ if (new_cfqq) {
+ if (!cfqq->new_cfqq)
+ cfq_setup_merge(cfqq, new_cfqq);
goto expire;
+ }
/*
* No requests pending. If the active queue still has requests in
* conditions to happen (or time out) before selecting a new queue.
*/
if (timer_pending(&cfqd->idle_slice_timer) ||
- (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
+ (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
cfqq = NULL;
goto keep_queue;
}
expire:
cfq_slice_expired(cfqd, 0);
new_queue:
+ /*
+ * Current queue expired. Check if we have to switch to a new
+ * service tree
+ */
+ if (!new_cfqq)
+ choose_service_tree(cfqd);
+
cfqq = cfq_set_active_queue(cfqd, new_cfqq);
keep_queue:
return cfqq;
{
struct cfq_queue *cfqq;
int dispatched = 0;
-
- while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
+ int i, j;
+ for (i = 0; i < 2; ++i)
+ for (j = 0; j < 3; ++j)
+ while ((cfqq = cfq_rb_first(&cfqd->service_trees[i][j]))
+ != NULL)
+ dispatched += __cfq_forced_dispatch_cfqq(cfqq);
+
+ while ((cfqq = cfq_rb_first(&cfqd->service_tree_idle)) != NULL)
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
cfq_slice_expired(cfqd, 0);
/*
* Drain async requests before we start sync IO
*/
- if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
+ if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
return false;
/*
static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
+ struct cfq_queue *__cfqq, *next;
+
if (unlikely(cfqq == cfqd->active_queue)) {
__cfq_slice_expired(cfqd, cfqq, 0);
cfq_schedule_dispatch(cfqd);
}
+ /*
+ * If this queue was scheduled to merge with another queue, be
+ * sure to drop the reference taken on that queue (and others in
+ * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
+ */
+ __cfqq = cfqq->new_cfqq;
+ while (__cfqq) {
+ if (__cfqq == cfqq) {
+ WARN(1, "cfqq->new_cfqq loop detected\n");
+ break;
+ }
+ next = __cfqq->new_cfqq;
+ cfq_put_queue(__cfqq);
+ __cfqq = next;
+ }
+
cfq_put_queue(cfqq);
}
total = cfqq->seek_total + (cfqq->seek_samples/2);
do_div(total, cfqq->seek_samples);
cfqq->seek_mean = (sector_t)total;
+
+ /*
+ * If this cfqq is shared between multiple processes, check to
+ * make sure that those processes are still issuing I/Os within
+ * the mean seek distance. If not, it may be time to break the
+ * queues apart again.
+ */
+ if (cfq_cfqq_coop(cfqq)) {
+ if (CFQQ_SEEKY(cfqq) && !cfqq->seeky_start)
+ cfqq->seeky_start = jiffies;
+ else if (!CFQQ_SEEKY(cfqq))
+ cfqq->seeky_start = 0;
+ }
}
/*
enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
- (!cfqd->cfq_latency && cfqd->hw_tag && CFQQ_SEEKY(cfqq)))
+ (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq)))
enable_idle = 0;
else if (sample_valid(cic->ttime_samples)) {
- unsigned int slice_idle = cfqd->cfq_slice_idle;
- if (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq))
- slice_idle = msecs_to_jiffies(CFQ_MIN_TT);
- if (cic->ttime_mean > slice_idle)
+ if (cic->ttime_mean > cfqd->cfq_slice_idle)
enable_idle = 0;
else
enable_idle = 1;
if (cfq_class_idle(cfqq))
return true;
+ if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD
+ && new_cfqq->service_tree == cfqq->service_tree)
+ return true;
+
/*
* if the new request is sync, but the currently running queue is
* not, let the sync request have priority.
* it's a metadata request and the current queue is doing regular IO.
*/
if (rq_is_meta(rq) && !cfqq->meta_pending)
- return false;
+ return true;
/*
* Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
cfq_log_cfqq(cfqd, cfqq, "insert_request");
cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
- cfq_add_rq_rb(rq);
-
rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
list_add_tail(&rq->queuelist, &cfqq->fifo);
+ cfq_add_rq_rb(rq);
cfq_rq_enqueued(cfqd, cfqq, rq);
}
*/
static void cfq_update_hw_tag(struct cfq_data *cfqd)
{
+ struct cfq_queue *cfqq = cfqd->active_queue;
+
if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
return;
+ /*
+ * If active queue hasn't enough requests and can idle, cfq might not
+ * dispatch sufficient requests to hardware. Don't zero hw_tag in this
+ * case
+ */
+ if (cfqq && cfq_cfqq_idle_window(cfqq) &&
+ cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
+ CFQ_HW_QUEUE_MIN && rq_in_driver(cfqd) < CFQ_HW_QUEUE_MIN)
+ return;
+
if (cfqd->hw_tag_samples++ < 50)
return;
*/
if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
cfq_slice_expired(cfqd, 1);
- else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
+ else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq) &&
sync && !rq_noidle(rq))
cfq_arm_slice_timer(cfqd);
}
cfqq->ioprio = IOPRIO_NORM;
} else {
/*
- * check if we need to unboost the queue
+ * unboost the queue (if needed)
*/
- if (cfqq->ioprio_class != cfqq->org_ioprio_class)
- cfqq->ioprio_class = cfqq->org_ioprio_class;
- if (cfqq->ioprio != cfqq->org_ioprio)
- cfqq->ioprio = cfqq->org_ioprio;
+ cfqq->ioprio_class = cfqq->org_ioprio_class;
+ cfqq->ioprio = cfqq->org_ioprio;
}
}
}
}
+static struct cfq_queue *
+cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
+ struct cfq_queue *cfqq)
+{
+ cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
+ cic_set_cfqq(cic, cfqq->new_cfqq, 1);
+ cfq_mark_cfqq_coop(cfqq->new_cfqq);
+ cfq_put_queue(cfqq);
+ return cic_to_cfqq(cic, 1);
+}
+
+static int should_split_cfqq(struct cfq_queue *cfqq)
+{
+ if (cfqq->seeky_start &&
+ time_after(jiffies, cfqq->seeky_start + CFQQ_COOP_TOUT))
+ return 1;
+ return 0;
+}
+
+/*
+ * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
+ * was the last process referring to said cfqq.
+ */
+static struct cfq_queue *
+split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
+{
+ if (cfqq_process_refs(cfqq) == 1) {
+ cfqq->seeky_start = 0;
+ cfqq->pid = current->pid;
+ cfq_clear_cfqq_coop(cfqq);
+ return cfqq;
+ }
+
+ cic_set_cfqq(cic, NULL, 1);
+ cfq_put_queue(cfqq);
+ return NULL;
+}
/*
* Allocate cfq data structures associated with this request.
*/
if (!cic)
goto queue_fail;
+new_queue:
cfqq = cic_to_cfqq(cic, is_sync);
if (!cfqq || cfqq == &cfqd->oom_cfqq) {
cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
cic_set_cfqq(cic, cfqq, is_sync);
+ } else {
+ /*
+ * If the queue was seeky for too long, break it apart.
+ */
+ if (cfq_cfqq_coop(cfqq) && should_split_cfqq(cfqq)) {
+ cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
+ cfqq = split_cfqq(cic, cfqq);
+ if (!cfqq)
+ goto new_queue;
+ }
+
+ /*
+ * Check to see if this queue is scheduled to merge with
+ * another, closely cooperating queue. The merging of
+ * queues happens here as it must be done in process context.
+ * The reference on new_cfqq was taken in merge_cfqqs.
+ */
+ if (cfqq->new_cfqq)
+ cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
}
cfqq->allocated[rw]++;
static void *cfq_init_queue(struct request_queue *q)
{
struct cfq_data *cfqd;
- int i;
+ int i, j;
cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
if (!cfqd)
return NULL;
- cfqd->service_tree = CFQ_RB_ROOT;
+ for (i = 0; i < 2; ++i)
+ for (j = 0; j < 3; ++j)
+ cfqd->service_trees[i][j] = CFQ_RB_ROOT;
+ cfqd->service_tree_idle = CFQ_RB_ROOT;
/*
* Not strictly needed (since RB_ROOT just clears the node and we
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff