[PATCH 03/21] blkcg: introduce blkg_stat and blkg_rwstat

From: Tejun Heo
Date: Wed Mar 28 2012 - 18:53:42 EST

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blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values
on 32bit archs and some stat counters have subtypes to distinguish
read/writes and sync/async IOs. The stat code paths are confusing and
involve a lot of going back and forth between blkcg core and specific
policy implementations, and synchronization and subtype handling are
open coded in blkcg core.

This patch introduces struct blkg_stat and blkg_rwstat which, with
accompanying operations, encapsulate stat updating and accessing with
proper synchronization.

blkg_stat is simple u64 counter with 64bit read-access protection.
blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw
flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and
replaces stat_sub_type indexed arrays.

All counters in blkio_group_stats and blkio_group_stats_cpu are
replaced with either blkg_stat or blkg_rwstat along with all users.

This does add one u64_stats_sync per counter and increase stats_sync
operations but they're empty/noops on 64bit archs and blkcg doesn't
have too many counters, especially with DEBUG_BLK_CGROUP off.

While the currently resulting code isn't necessarily simpler at the
moment, this will enable further clean up of blkcg stats code.

- BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to
BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}.

- blkg_stat_add() replaces blkio_add_stat() and
blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the
latter function no longer exists. It's *way* better to have
underflowed stat counters than oopsing.

- blkio_group_stats->dequeue is now a proper u64 stat counter instead
of ulong.

- reset_stats() updated to clear each stat counters individually and
BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed.

- Some functions reconstruct rw flags from direction and sync
booleans. This will be removed by future patches.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
block/blk-cgroup.c | 289 +++++++++++++++++++++++-----------------------------
block/blk-cgroup.h | 211 ++++++++++++++++++++++++++++++--------
2 files changed, 293 insertions(+), 207 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index d4cf77d..153a2db 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -132,46 +132,6 @@ static inline void blkio_update_group_iops(struct blkio_group *blkg,
}
}

-/*
- * Add to the appropriate stat variable depending on the request type.
- * This should be called with queue_lock held.
- */
-static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
- bool sync)
-{
- if (direction)
- stat[BLKIO_STAT_WRITE] += add;
- else
- stat[BLKIO_STAT_READ] += add;
- if (sync)
- stat[BLKIO_STAT_SYNC] += add;
- else
- stat[BLKIO_STAT_ASYNC] += add;
-}
-
-/*
- * Decrements the appropriate stat variable if non-zero depending on the
- * request type. Panics on value being zero.
- * This should be called with the queue_lock held.
- */
-static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
-{
- if (direction) {
- BUG_ON(stat[BLKIO_STAT_WRITE] == 0);
- stat[BLKIO_STAT_WRITE]--;
- } else {
- BUG_ON(stat[BLKIO_STAT_READ] == 0);
- stat[BLKIO_STAT_READ]--;
- }
- if (sync) {
- BUG_ON(stat[BLKIO_STAT_SYNC] == 0);
- stat[BLKIO_STAT_SYNC]--;
- } else {
- BUG_ON(stat[BLKIO_STAT_ASYNC] == 0);
- stat[BLKIO_STAT_ASYNC]--;
- }
-}
-
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* This should be called with the queue_lock held. */
static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
@@ -198,7 +158,8 @@ static void blkio_update_group_wait_time(struct blkio_group_stats *stats)

now = sched_clock();
if (time_after64(now, stats->start_group_wait_time))
- stats->group_wait_time += now - stats->start_group_wait_time;
+ blkg_stat_add(&stats->group_wait_time,
+ now - stats->start_group_wait_time);
blkio_clear_blkg_waiting(stats);
}

@@ -212,7 +173,8 @@ static void blkio_end_empty_time(struct blkio_group_stats *stats)

now = sched_clock();
if (time_after64(now, stats->start_empty_time))
- stats->empty_time += now - stats->start_empty_time;
+ blkg_stat_add(&stats->empty_time,
+ now - stats->start_empty_time);
blkio_clear_blkg_empty(stats);
}

@@ -239,11 +201,9 @@ void blkiocg_update_idle_time_stats(struct blkio_group *blkg,
if (blkio_blkg_idling(stats)) {
unsigned long long now = sched_clock();

- if (time_after64(now, stats->start_idle_time)) {
- u64_stats_update_begin(&stats->syncp);
- stats->idle_time += now - stats->start_idle_time;
- u64_stats_update_end(&stats->syncp);
- }
+ if (time_after64(now, stats->start_idle_time))
+ blkg_stat_add(&stats->idle_time,
+ now - stats->start_idle_time);
blkio_clear_blkg_idling(stats);
}
}
@@ -256,13 +216,10 @@ void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg,

lockdep_assert_held(blkg->q->queue_lock);

- u64_stats_update_begin(&stats->syncp);
- stats->avg_queue_size_sum +=
- stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
- stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
- stats->avg_queue_size_samples++;
+ blkg_stat_add(&stats->avg_queue_size_sum,
+ blkg_rwstat_sum(&stats->queued));
+ blkg_stat_add(&stats->avg_queue_size_samples, 1);
blkio_update_group_wait_time(stats);
- u64_stats_update_end(&stats->syncp);
}
EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);

@@ -273,8 +230,7 @@ void blkiocg_set_start_empty_time(struct blkio_group *blkg,

lockdep_assert_held(blkg->q->queue_lock);

- if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] ||
- stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE])
+ if (blkg_rwstat_sum(&stats->queued))
return;

/*
@@ -298,7 +254,7 @@ void blkiocg_update_dequeue_stats(struct blkio_group *blkg,

lockdep_assert_held(blkg->q->queue_lock);

- pd->stats.dequeue += dequeue;
+ blkg_stat_add(&pd->stats.dequeue, dequeue);
}
EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
#else
@@ -314,14 +270,12 @@ void blkiocg_update_io_add_stats(struct blkio_group *blkg,
bool sync)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
+ int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);

lockdep_assert_held(blkg->q->queue_lock);

- u64_stats_update_begin(&stats->syncp);
- blkio_add_stat(stats->stat_arr[BLKIO_STAT_QUEUED], 1, direction, sync);
+ blkg_rwstat_add(&stats->queued, rw, 1);
blkio_end_empty_time(stats);
- u64_stats_update_end(&stats->syncp);
-
blkio_set_start_group_wait_time(blkg, pol, curr_blkg);
}
EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
@@ -331,13 +285,11 @@ void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
bool direction, bool sync)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
+ int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);

lockdep_assert_held(blkg->q->queue_lock);

- u64_stats_update_begin(&stats->syncp);
- blkio_check_and_dec_stat(stats->stat_arr[BLKIO_STAT_QUEUED], direction,
- sync);
- u64_stats_update_end(&stats->syncp);
+ blkg_rwstat_add(&stats->queued, rw, -1);
}
EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);

@@ -350,12 +302,10 @@ void blkiocg_update_timeslice_used(struct blkio_group *blkg,

lockdep_assert_held(blkg->q->queue_lock);

- u64_stats_update_begin(&stats->syncp);
- stats->time += time;
+ blkg_stat_add(&stats->time, time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
- stats->unaccounted_time += unaccounted_time;
+ blkg_stat_add(&stats->unaccounted_time, unaccounted_time);
#endif
- u64_stats_update_end(&stats->syncp);
}
EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);

@@ -367,6 +317,7 @@ void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
struct blkio_policy_type *pol,
uint64_t bytes, bool direction, bool sync)
{
+ int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);
struct blkg_policy_data *pd = blkg->pd[pol->plid];
struct blkio_group_stats_cpu *stats_cpu;
unsigned long flags;
@@ -384,13 +335,10 @@ void blkiocg_update_dispatch_stats(struct blkio_group *blkg,

stats_cpu = this_cpu_ptr(pd->stats_cpu);

- u64_stats_update_begin(&stats_cpu->syncp);
- stats_cpu->sectors += bytes >> 9;
- blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICED],
- 1, direction, sync);
- blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICE_BYTES],
- bytes, direction, sync);
- u64_stats_update_end(&stats_cpu->syncp);
+ blkg_stat_add(&stats_cpu->sectors, bytes >> 9);
+ blkg_rwstat_add(&stats_cpu->serviced, rw, 1);
+ blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
+
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
@@ -403,17 +351,15 @@ void blkiocg_update_completion_stats(struct blkio_group *blkg,
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
unsigned long long now = sched_clock();
+ int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);

lockdep_assert_held(blkg->q->queue_lock);

- u64_stats_update_begin(&stats->syncp);
if (time_after64(now, io_start_time))
- blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
- now - io_start_time, direction, sync);
+ blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
if (time_after64(io_start_time, start_time))
- blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME],
- io_start_time - start_time, direction, sync);
- u64_stats_update_end(&stats->syncp);
+ blkg_rwstat_add(&stats->wait_time, rw,
+ io_start_time - start_time);
}
EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);

@@ -423,12 +369,11 @@ void blkiocg_update_io_merged_stats(struct blkio_group *blkg,
bool direction, bool sync)
{
struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
+ int rw = (direction ? REQ_WRITE : 0) | (sync ? REQ_SYNC : 0);

lockdep_assert_held(blkg->q->queue_lock);

- u64_stats_update_begin(&stats->syncp);
- blkio_add_stat(stats->stat_arr[BLKIO_STAT_MERGED], 1, direction, sync);
- u64_stats_update_end(&stats->syncp);
+ blkg_rwstat_add(&stats->merged, rw, 1);
}
EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);

@@ -757,8 +702,9 @@ static void blkio_reset_stats_cpu(struct blkio_group *blkg, int plid)
struct blkio_group_stats_cpu *sc =
per_cpu_ptr(pd->stats_cpu, cpu);

- sc->sectors = 0;
- memset(sc->stat_arr_cpu, 0, sizeof(sc->stat_arr_cpu));
+ blkg_rwstat_reset(&sc->service_bytes);
+ blkg_rwstat_reset(&sc->serviced);
+ blkg_stat_reset(&sc->sectors);
}
}

@@ -768,7 +714,6 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
struct blkio_group *blkg;
struct hlist_node *n;
- int i;

spin_lock(&blkio_list_lock);
spin_lock_irq(&blkcg->lock);
@@ -786,14 +731,18 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
struct blkio_group_stats *stats = &pd->stats;

/* queued stats shouldn't be cleared */
- for (i = 0; i < ARRAY_SIZE(stats->stat_arr); i++)
- if (i != BLKIO_STAT_QUEUED)
- memset(stats->stat_arr[i], 0,
- sizeof(stats->stat_arr[i]));
- stats->time = 0;
+ blkg_rwstat_reset(&stats->merged);
+ blkg_rwstat_reset(&stats->service_time);
+ blkg_rwstat_reset(&stats->wait_time);
+ blkg_stat_reset(&stats->time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
- memset((void *)stats + BLKG_STATS_DEBUG_CLEAR_START, 0,
- BLKG_STATS_DEBUG_CLEAR_SIZE);
+ blkg_stat_reset(&stats->unaccounted_time);
+ blkg_stat_reset(&stats->avg_queue_size_sum);
+ blkg_stat_reset(&stats->avg_queue_size_samples);
+ blkg_stat_reset(&stats->dequeue);
+ blkg_stat_reset(&stats->group_wait_time);
+ blkg_stat_reset(&stats->idle_time);
+ blkg_stat_reset(&stats->empty_time);
#endif
blkio_reset_stats_cpu(blkg, pol->plid);
}
@@ -804,7 +753,7 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
return 0;
}

-static void blkio_get_key_name(enum stat_sub_type type, const char *dname,
+static void blkio_get_key_name(enum blkg_rwstat_type type, const char *dname,
char *str, int chars_left, bool diskname_only)
{
snprintf(str, chars_left, "%s", dname);
@@ -817,19 +766,19 @@ static void blkio_get_key_name(enum stat_sub_type type, const char *dname,
if (diskname_only)
return;
switch (type) {
- case BLKIO_STAT_READ:
+ case BLKG_RWSTAT_READ:
strlcat(str, " Read", chars_left);
break;
- case BLKIO_STAT_WRITE:
+ case BLKG_RWSTAT_WRITE:
strlcat(str, " Write", chars_left);
break;
- case BLKIO_STAT_SYNC:
+ case BLKG_RWSTAT_SYNC:
strlcat(str, " Sync", chars_left);
break;
- case BLKIO_STAT_ASYNC:
+ case BLKG_RWSTAT_ASYNC:
strlcat(str, " Async", chars_left);
break;
- case BLKIO_STAT_TOTAL:
+ case BLKG_RWSTAT_TOTAL:
strlcat(str, " Total", chars_left);
break;
default:
@@ -838,29 +787,34 @@ static void blkio_get_key_name(enum stat_sub_type type, const char *dname,
}

static uint64_t blkio_read_stat_cpu(struct blkio_group *blkg, int plid,
- enum stat_type_cpu type, enum stat_sub_type sub_type)
+ enum stat_type_cpu type,
+ enum blkg_rwstat_type sub_type)
{
struct blkg_policy_data *pd = blkg->pd[plid];
+ u64 val = 0;
int cpu;
- struct blkio_group_stats_cpu *stats_cpu;
- u64 val = 0, tval;

if (pd->stats_cpu == NULL)
return val;

for_each_possible_cpu(cpu) {
- unsigned int start;
- stats_cpu = per_cpu_ptr(pd->stats_cpu, cpu);
-
- do {
- start = u64_stats_fetch_begin(&stats_cpu->syncp);
- if (type == BLKIO_STAT_CPU_SECTORS)
- tval = stats_cpu->sectors;
- else
- tval = stats_cpu->stat_arr_cpu[type][sub_type];
- } while(u64_stats_fetch_retry(&stats_cpu->syncp, start));
-
- val += tval;
+ struct blkio_group_stats_cpu *stats_cpu =
+ per_cpu_ptr(pd->stats_cpu, cpu);
+ struct blkg_rwstat rws;
+
+ switch (type) {
+ case BLKIO_STAT_CPU_SECTORS:
+ val += blkg_stat_read(&stats_cpu->sectors);
+ break;
+ case BLKIO_STAT_CPU_SERVICE_BYTES:
+ rws = blkg_rwstat_read(&stats_cpu->service_bytes);
+ val += rws.cnt[sub_type];
+ break;
+ case BLKIO_STAT_CPU_SERVICED:
+ rws = blkg_rwstat_read(&stats_cpu->serviced);
+ val += rws.cnt[sub_type];
+ break;
+ }
}

return val;
@@ -872,7 +826,7 @@ static uint64_t blkio_get_stat_cpu(struct blkio_group *blkg, int plid,
{
uint64_t disk_total, val;
char key_str[MAX_KEY_LEN];
- enum stat_sub_type sub_type;
+ enum blkg_rwstat_type sub_type;

if (type == BLKIO_STAT_CPU_SECTORS) {
val = blkio_read_stat_cpu(blkg, plid, type, 0);
@@ -881,7 +835,7 @@ static uint64_t blkio_get_stat_cpu(struct blkio_group *blkg, int plid,
return val;
}

- for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
+ for (sub_type = BLKG_RWSTAT_READ; sub_type < BLKG_RWSTAT_NR;
sub_type++) {
blkio_get_key_name(sub_type, dname, key_str, MAX_KEY_LEN,
false);
@@ -889,10 +843,10 @@ static uint64_t blkio_get_stat_cpu(struct blkio_group *blkg, int plid,
cb->fill(cb, key_str, val);
}

- disk_total = blkio_read_stat_cpu(blkg, plid, type, BLKIO_STAT_READ) +
- blkio_read_stat_cpu(blkg, plid, type, BLKIO_STAT_WRITE);
+ disk_total = blkio_read_stat_cpu(blkg, plid, type, BLKG_RWSTAT_READ) +
+ blkio_read_stat_cpu(blkg, plid, type, BLKG_RWSTAT_WRITE);

- blkio_get_key_name(BLKIO_STAT_TOTAL, dname, key_str, MAX_KEY_LEN,
+ blkio_get_key_name(BLKG_RWSTAT_TOTAL, dname, key_str, MAX_KEY_LEN,
false);
cb->fill(cb, key_str, disk_total);
return disk_total;
@@ -905,65 +859,76 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg, int plid,
struct blkio_group_stats *stats = &blkg->pd[plid]->stats;
uint64_t v = 0, disk_total = 0;
char key_str[MAX_KEY_LEN];
- unsigned int sync_start;
+ struct blkg_rwstat rws = { };
int st;

if (type >= BLKIO_STAT_ARR_NR) {
- do {
- sync_start = u64_stats_fetch_begin(&stats->syncp);
- switch (type) {
- case BLKIO_STAT_TIME:
- v = stats->time;
- break;
+ switch (type) {
+ case BLKIO_STAT_TIME:
+ v = blkg_stat_read(&stats->time);
+ break;
#ifdef CONFIG_DEBUG_BLK_CGROUP
- case BLKIO_STAT_UNACCOUNTED_TIME:
- v = stats->unaccounted_time;
- break;
- case BLKIO_STAT_AVG_QUEUE_SIZE: {
- uint64_t samples = stats->avg_queue_size_samples;
+ case BLKIO_STAT_UNACCOUNTED_TIME:
+ v = blkg_stat_read(&stats->unaccounted_time);
+ break;
+ case BLKIO_STAT_AVG_QUEUE_SIZE: {
+ uint64_t samples;

- if (samples) {
- v = stats->avg_queue_size_sum;
- do_div(v, samples);
- }
- break;
+ samples = blkg_stat_read(&stats->avg_queue_size_samples);
+ if (samples) {
+ v = blkg_stat_read(&stats->avg_queue_size_sum);
+ do_div(v, samples);
}
- case BLKIO_STAT_IDLE_TIME:
- v = stats->idle_time;
- break;
- case BLKIO_STAT_EMPTY_TIME:
- v = stats->empty_time;
- break;
- case BLKIO_STAT_DEQUEUE:
- v = stats->dequeue;
- break;
- case BLKIO_STAT_GROUP_WAIT_TIME:
- v = stats->group_wait_time;
- break;
+ break;
+ }
+ case BLKIO_STAT_IDLE_TIME:
+ v = blkg_stat_read(&stats->idle_time);
+ break;
+ case BLKIO_STAT_EMPTY_TIME:
+ v = blkg_stat_read(&stats->empty_time);
+ break;
+ case BLKIO_STAT_DEQUEUE:
+ v = blkg_stat_read(&stats->dequeue);
+ break;
+ case BLKIO_STAT_GROUP_WAIT_TIME:
+ v = blkg_stat_read(&stats->group_wait_time);
+ break;
#endif
- default:
- WARN_ON_ONCE(1);
- }
- } while (u64_stats_fetch_retry(&stats->syncp, sync_start));
+ default:
+ WARN_ON_ONCE(1);
+ }

blkio_get_key_name(0, dname, key_str, MAX_KEY_LEN, true);
cb->fill(cb, key_str, v);
return v;
}

- for (st = BLKIO_STAT_READ; st < BLKIO_STAT_TOTAL; st++) {
- do {
- sync_start = u64_stats_fetch_begin(&stats->syncp);
- v = stats->stat_arr[type][st];
- } while (u64_stats_fetch_retry(&stats->syncp, sync_start));
+ switch (type) {
+ case BLKIO_STAT_MERGED:
+ rws = blkg_rwstat_read(&stats->merged);
+ break;
+ case BLKIO_STAT_SERVICE_TIME:
+ rws = blkg_rwstat_read(&stats->service_time);
+ break;
+ case BLKIO_STAT_WAIT_TIME:
+ rws = blkg_rwstat_read(&stats->wait_time);
+ break;
+ case BLKIO_STAT_QUEUED:
+ rws = blkg_rwstat_read(&stats->queued);
+ break;
+ default:
+ WARN_ON_ONCE(true);
+ break;
+ }

+ for (st = BLKG_RWSTAT_READ; st < BLKG_RWSTAT_NR; st++) {
blkio_get_key_name(st, dname, key_str, MAX_KEY_LEN, false);
- cb->fill(cb, key_str, v);
- if (st == BLKIO_STAT_READ || st == BLKIO_STAT_WRITE)
- disk_total += v;
+ cb->fill(cb, key_str, rws.cnt[st]);
+ if (st == BLKG_RWSTAT_READ || st == BLKG_RWSTAT_WRITE)
+ disk_total += rws.cnt[st];
}

- blkio_get_key_name(BLKIO_STAT_TOTAL, dname, key_str, MAX_KEY_LEN,
+ blkio_get_key_name(BLKG_RWSTAT_TOTAL, dname, key_str, MAX_KEY_LEN,
false);
cb->fill(cb, key_str, disk_total);
return disk_total;
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 2060d81..7578df3 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -69,12 +69,14 @@ enum stat_type_cpu {

#define BLKIO_STAT_CPU_ARR_NR (BLKIO_STAT_CPU_SERVICED + 1)

-enum stat_sub_type {
- BLKIO_STAT_READ = 0,
- BLKIO_STAT_WRITE,
- BLKIO_STAT_SYNC,
- BLKIO_STAT_ASYNC,
- BLKIO_STAT_TOTAL
+enum blkg_rwstat_type {
+ BLKG_RWSTAT_READ,
+ BLKG_RWSTAT_WRITE,
+ BLKG_RWSTAT_SYNC,
+ BLKG_RWSTAT_ASYNC,
+
+ BLKG_RWSTAT_NR,
+ BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
};

/* blkg state flags */
@@ -124,54 +126,58 @@ struct blkio_cgroup {
uint64_t id;
};

+struct blkg_stat {
+ struct u64_stats_sync syncp;
+ uint64_t cnt;
+};
+
+struct blkg_rwstat {
+ struct u64_stats_sync syncp;
+ uint64_t cnt[BLKG_RWSTAT_NR];
+};
+
struct blkio_group_stats {
- struct u64_stats_sync syncp;
+ /* number of ios merged */
+ struct blkg_rwstat merged;
+ /* total time spent on device in ns, may not be accurate w/ queueing */
+ struct blkg_rwstat service_time;
+ /* total time spent waiting in scheduler queue in ns */
+ struct blkg_rwstat wait_time;
+ /* number of IOs queued up */
+ struct blkg_rwstat queued;
/* total disk time and nr sectors dispatched by this group */
- uint64_t time;
- uint64_t stat_arr[BLKIO_STAT_ARR_NR][BLKIO_STAT_TOTAL];
+ struct blkg_stat time;
#ifdef CONFIG_DEBUG_BLK_CGROUP
- /* Time not charged to this cgroup */
- uint64_t unaccounted_time;
-
- /* Sum of number of IOs queued across all samples */
- uint64_t avg_queue_size_sum;
- /* Count of samples taken for average */
- uint64_t avg_queue_size_samples;
- /* How many times this group has been removed from service tree */
- unsigned long dequeue;
-
- /* Total time spent waiting for it to be assigned a timeslice. */
- uint64_t group_wait_time;
-
- /* Time spent idling for this blkio_group */
- uint64_t idle_time;
- /*
- * Total time when we have requests queued and do not contain the
- * current active queue.
- */
- uint64_t empty_time;
-
+ /* time not charged to this cgroup */
+ struct blkg_stat unaccounted_time;
+ /* sum of number of ios queued across all samples */
+ struct blkg_stat avg_queue_size_sum;
+ /* count of samples taken for average */
+ struct blkg_stat avg_queue_size_samples;
+ /* how many times this group has been removed from service tree */
+ struct blkg_stat dequeue;
+ /* total time spent waiting for it to be assigned a timeslice. */
+ struct blkg_stat group_wait_time;
+ /* time spent idling for this blkio_group */
+ struct blkg_stat idle_time;
+ /* total time with empty current active q with other requests queued */
+ struct blkg_stat empty_time;
/* fields after this shouldn't be cleared on stat reset */
- uint64_t start_group_wait_time;
- uint64_t start_idle_time;
- uint64_t start_empty_time;
- uint16_t flags;
+ uint64_t start_group_wait_time;
+ uint64_t start_idle_time;
+ uint64_t start_empty_time;
+ uint16_t flags;
#endif
};

-#ifdef CONFIG_DEBUG_BLK_CGROUP
-#define BLKG_STATS_DEBUG_CLEAR_START \
- offsetof(struct blkio_group_stats, unaccounted_time)
-#define BLKG_STATS_DEBUG_CLEAR_SIZE \
- (offsetof(struct blkio_group_stats, start_group_wait_time) - \
- BLKG_STATS_DEBUG_CLEAR_START)
-#endif
-
/* Per cpu blkio group stats */
struct blkio_group_stats_cpu {
- uint64_t sectors;
- uint64_t stat_arr_cpu[BLKIO_STAT_CPU_ARR_NR][BLKIO_STAT_TOTAL];
- struct u64_stats_sync syncp;
+ /* total bytes transferred */
+ struct blkg_rwstat service_bytes;
+ /* total IOs serviced, post merge */
+ struct blkg_rwstat serviced;
+ /* total sectors transferred */
+ struct blkg_stat sectors;
};

struct blkio_group_conf {
@@ -316,6 +322,121 @@ static inline void blkg_put(struct blkio_group *blkg)
__blkg_release(blkg);
}

+/**
+ * blkg_stat_add - add a value to a blkg_stat
+ * @stat: target blkg_stat
+ * @val: value to add
+ *
+ * Add @val to @stat. The caller is responsible for synchronizing calls to
+ * this function.
+ */
+static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
+{
+ u64_stats_update_begin(&stat->syncp);
+ stat->cnt += val;
+ u64_stats_update_end(&stat->syncp);
+}
+
+/**
+ * blkg_stat_read - read the current value of a blkg_stat
+ * @stat: blkg_stat to read
+ *
+ * Read the current value of @stat. This function can be called without
+ * synchroniztion and takes care of u64 atomicity.
+ */
+static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
+{
+ unsigned int start;
+ uint64_t v;
+
+ do {
+ start = u64_stats_fetch_begin(&stat->syncp);
+ v = stat->cnt;
+ } while (u64_stats_fetch_retry(&stat->syncp, start));
+
+ return v;
+}
+
+/**
+ * blkg_stat_reset - reset a blkg_stat
+ * @stat: blkg_stat to reset
+ */
+static inline void blkg_stat_reset(struct blkg_stat *stat)
+{
+ stat->cnt = 0;
+}
+
+/**
+ * blkg_rwstat_add - add a value to a blkg_rwstat
+ * @rwstat: target blkg_rwstat
+ * @rw: mask of REQ_{WRITE|SYNC}
+ * @val: value to add
+ *
+ * Add @val to @rwstat. The counters are chosen according to @rw. The
+ * caller is responsible for synchronizing calls to this function.
+ */
+static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
+ int rw, uint64_t val)
+{
+ u64_stats_update_begin(&rwstat->syncp);
+
+ if (rw & REQ_WRITE)
+ rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
+ else
+ rwstat->cnt[BLKG_RWSTAT_READ] += val;
+ if (rw & REQ_SYNC)
+ rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
+ else
+ rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
+
+ u64_stats_update_end(&rwstat->syncp);
+}
+
+/**
+ * blkg_rwstat_read - read the current values of a blkg_rwstat
+ * @rwstat: blkg_rwstat to read
+ *
+ * Read the current snapshot of @rwstat and return it as the return value.
+ * This function can be called without synchronization and takes care of
+ * u64 atomicity.
+ */
+static struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
+{
+ unsigned int start;
+ struct blkg_rwstat tmp;
+
+ do {
+ start = u64_stats_fetch_begin(&rwstat->syncp);
+ tmp = *rwstat;
+ } while (u64_stats_fetch_retry(&rwstat->syncp, start));
+
+ return tmp;
+}
+
+/**
+ * blkg_rwstat_sum - read the total count of a blkg_rwstat
+ * @rwstat: blkg_rwstat to read
+ *
+ * Return the total count of @rwstat regardless of the IO direction. This
+ * function can be called without synchronization and takes care of u64
+ * atomicity.
+ */
+static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
+{
+ struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
+
+ return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
+}
+
+/**
+ * blkg_rwstat_reset - reset a blkg_rwstat
+ * @rwstat: blkg_rwstat to reset
+ */
+static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
+{
+ memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
+}
+
#else

struct blkio_group {
--
1.7.7.3

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