Merge branch 'cfq-2.6.33' into for-2.6.33

This commit is contained in:
Jens Axboe 2009-11-03 21:12:10 +01:00
commit 150e6c67f4

View file

@ -27,6 +27,8 @@ static const int cfq_slice_sync = HZ / 10;
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
@ -73,8 +75,9 @@ static DEFINE_SPINLOCK(ioc_gone_lock);
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
@ -126,9 +129,30 @@ struct cfq_queue {
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
*/
@ -136,9 +160,17 @@ 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
@ -148,6 +180,7 @@ struct cfq_data {
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;
@ -199,6 +232,16 @@ struct cfq_data {
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 */
@ -243,6 +286,35 @@ CFQ_CFQQ_FNS(coop);
#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);
@ -315,10 +387,49 @@ cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
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);
}
@ -457,6 +568,7 @@ static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
if (root->left == n)
root->left = NULL;
rb_erase_init(n, &root->rb);
--root->count;
}
/*
@ -497,7 +609,7 @@ static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
}
/*
* 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.
*/
@ -507,11 +619,13 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
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;
@ -529,7 +643,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
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;
}
@ -537,15 +651,18 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
/*
* 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;
@ -553,35 +670,25 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
__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))
if (time_before(rb_key, __cfqq->rb_key))
n = &(*p)->rb_left;
else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
else {
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))
n = &(*p)->rb_left;
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 *
@ -683,8 +790,10 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
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;
@ -945,10 +1054,12 @@ 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)
{
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);
}
/*
@ -1065,9 +1176,45 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
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;
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;
@ -1088,7 +1235,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
/*
* 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;
/*
@ -1115,14 +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);
@ -1226,6 +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.
@ -1270,7 +1523,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
* 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;
}
@ -1278,6 +1531,13 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
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;
@ -1304,8 +1564,14 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq;
int dispatched = 0;
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)) != NULL)
while ((cfqq = cfq_rb_first(&cfqd->service_tree_idle)) != NULL)
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
cfq_slice_expired(cfqd, 0);
@ -1323,7 +1589,7 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
/*
* 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;
/*
@ -2086,13 +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;
@ -2130,6 +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.
@ -2243,10 +2510,9 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
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);
}
@ -2645,13 +2911,16 @@ 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;
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