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blkio: Group time used accounting and workload context save restore

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o This patch introduces the functionality to do the accounting of group time
  when a queue expires. This time used decides which is the group to go
  next.

o Also introduce the functionlity to save and restore the workload type
  context with-in group. It might happen that once we expire the cfq queue
  and group, a different group will schedule in and we will lose the context
  of the workload type. Hence save and restore it upon queue expiry.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Vivek Goyal 2009-12-03 12:59:45 -05:00 committed by Jens Axboe
parent 58ff82f34c
commit dae739ebc4
1 changed files with 79 additions and 0 deletions
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79
block/cfq-iosched.c
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@ -115,6 +115,10 @@ struct cfq_queue {
/* fifo list of requests in sort_list */
struct list_head fifo;
/* time when queue got scheduled in to dispatch first request. */
unsigned long dispatch_start;
/* time when first request from queue completed and slice started. */
unsigned long slice_start;
unsigned long slice_end;
long slice_resid;
unsigned int slice_dispatch;
@ -181,6 +185,10 @@ struct cfq_group {
*/
struct cfq_rb_root service_trees[2][3];
struct cfq_rb_root service_tree_idle;
unsigned long saved_workload_slice;
enum wl_type_t saved_workload;
enum wl_prio_t saved_serving_prio;
};
/*
@ -543,6 +551,7 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
low_slice);
}
}
cfqq->slice_start = jiffies;
cfqq->slice_end = jiffies + slice;
cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
}
@ -818,6 +827,58 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
st->total_weight -= cfqg->weight;
if (!RB_EMPTY_NODE(&cfqg->rb_node))
cfq_rb_erase(&cfqg->rb_node, st);
cfqg->saved_workload_slice = 0;
}
static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
{
unsigned int slice_used, allocated_slice;
/*
* Queue got expired before even a single request completed or
* got expired immediately after first request completion.
*/
if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
/*
* Also charge the seek time incurred to the group, otherwise
* if there are mutiple queues in the group, each can dispatch
* a single request on seeky media and cause lots of seek time
* and group will never know it.
*/
slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1);
} else {
slice_used = jiffies - cfqq->slice_start;
allocated_slice = cfqq->slice_end - cfqq->slice_start;
if (slice_used > allocated_slice)
slice_used = allocated_slice;
}
cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u", slice_used);
return slice_used;
}
static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
struct cfq_queue *cfqq)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
unsigned int used_sl;
used_sl = cfq_cfqq_slice_usage(cfqq);
/* Can't update vdisktime while group is on service tree */
cfq_rb_erase(&cfqg->rb_node, st);
cfqg->vdisktime += cfq_scale_slice(used_sl, cfqg);
__cfq_group_service_tree_add(st, cfqg);
/* This group is being expired. Save the context */
if (time_after(cfqd->workload_expires, jiffies)) {
cfqg->saved_workload_slice = cfqd->workload_expires
- jiffies;
cfqg->saved_workload = cfqd->serving_type;
cfqg->saved_serving_prio = cfqd->serving_prio;
} else
cfqg->saved_workload_slice = 0;
}
/*
@ -833,6 +894,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
unsigned long rb_key;
struct cfq_rb_root *service_tree;
int left;
int new_cfqq = 1;
service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
cfqq_type(cfqq), cfqd);
@ -861,6 +923,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
}
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
new_cfqq = 0;
/*
* same position, nothing more to do
*/
@ -902,6 +965,8 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
rb_link_node(&cfqq->rb_node, parent, p);
rb_insert_color(&cfqq->rb_node, &service_tree->rb);
service_tree->count++;
if (add_front || !new_cfqq)
return;
cfq_group_service_tree_add(cfqd, cfqq->cfqg);
}
@ -1218,6 +1283,8 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
{
if (cfqq) {
cfq_log_cfqq(cfqd, cfqq, "set_active");
cfqq->slice_start = 0;
cfqq->dispatch_start = jiffies;
cfqq->slice_end = 0;
cfqq->slice_dispatch = 0;
@ -1255,6 +1322,8 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
}
cfq_group_served(cfqd, cfqq->cfqg, cfqq);
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
cfq_del_cfqq_rr(cfqd, cfqq);
@ -1263,6 +1332,9 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (cfqq == cfqd->active_queue)
cfqd->active_queue = NULL;
if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active)
cfqd->grp_service_tree.active = NULL;
if (cfqd->active_cic) {
put_io_context(cfqd->active_cic->ioc);
cfqd->active_cic = NULL;
@ -1747,6 +1819,13 @@ static void cfq_choose_cfqg(struct cfq_data *cfqd)
struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
cfqd->serving_group = cfqg;
/* Restore the workload type data */
if (cfqg->saved_workload_slice) {
cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
cfqd->serving_type = cfqg->saved_workload;
cfqd->serving_prio = cfqg->saved_serving_prio;
}
choose_service_tree(cfqd, cfqg);
}