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-rw-r--r--block/cfq-iosched.c200
1 files changed, 168 insertions, 32 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 76afa369689..859f534ae9e 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -134,7 +134,7 @@ struct cfq_queue {
};
/*
- * Index in the service_trees.
+ * First index in the service_trees.
* IDLE is handled separately, so it has negative index
*/
enum wl_prio_t {
@@ -144,6 +144,16 @@ enum wl_prio_t {
};
/*
+ * 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 {
@@ -153,12 +163,14 @@ struct cfq_data {
* 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_trees[2];
+ 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
@@ -221,12 +233,13 @@ struct cfq_data {
};
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];
+ return &cfqd->service_trees[prio][type];
}
enum cfqq_state_flags {
@@ -282,12 +295,24 @@ static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
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].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 *);
@@ -597,7 +622,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_rb_root *service_tree;
int left;
- service_tree = service_tree_for(cfqq_prio(cfqq), cfqd);
+ 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(&service_tree->rb);
@@ -1030,7 +1055,7 @@ static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
{
struct cfq_rb_root *service_tree =
- service_tree_for(cfqd->serving_prio, cfqd);
+ service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd);
if (RB_EMPTY_ROOT(&service_tree->rb))
return NULL;
@@ -1167,7 +1192,7 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
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;
+ struct cfq_rb_root *service_tree = cfqq->service_tree;
/* We never do for idle class queues. */
if (prio == IDLE_WORKLOAD)
@@ -1181,7 +1206,9 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
* Otherwise, we do only if they are the last ones
* in their service tree.
*/
- service_tree = service_tree_for(prio, cfqd);
+ if (!service_tree)
+ service_tree = service_tree_for(prio, cfqq_type(cfqq), cfqd);
+
if (service_tree->count == 0)
return true;
@@ -1235,14 +1262,20 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
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);
@@ -1346,6 +1379,106 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
}
}
+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.
@@ -1398,14 +1531,13 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
expire:
cfq_slice_expired(cfqd, 0);
new_queue:
- if (!new_cfqq) {
- 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;
- }
+ /*
+ * 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;
@@ -1432,10 +1564,12 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq;
int dispatched = 0;
- int i;
+ int i, j;
for (i = 0; i < 2; ++i)
- while ((cfqq = cfq_rb_first(&cfqd->service_trees[i])) != NULL)
- dispatched += __cfq_forced_dispatch_cfqq(cfqq);
+ 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);
@@ -2218,13 +2352,10 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
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;
@@ -2262,6 +2393,10 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
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.
@@ -2778,14 +2913,15 @@ static void cfq_exit_queue(struct elevator_queue *e)
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;
for (i = 0; i < 2; ++i)
- cfqd->service_trees[i] = CFQ_RB_ROOT;
+ for (j = 0; j < 3; ++j)
+ cfqd->service_trees[i][j] = CFQ_RB_ROOT;
cfqd->service_tree_idle = CFQ_RB_ROOT;
/*
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-23 12:51:31 +0000