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blk-cgroup: introduce a new struct blkg_rwstat_sample 

When sampling the blkcg counts we don't need atomics or per-cpu
variables.  Introduce a new structure just containing plain u64
counters.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2019-06-06 12:26:21 +02:00 committed by Jens Axboe
parent 5d0b6e48cb
commit 7af6fd9112
3 changed files with 35 additions and 36 deletions
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10
block/bfq-cgroup.c
View File

@ -935,7 +935,7 @@ static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf, static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
struct blkg_policy_data *pd, int off) struct blkg_policy_data *pd, int off)
{ {
struct blkg_rwstat sum; struct blkg_rwstat_sample sum;
blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off, &sum); blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off, &sum);
return __blkg_prfill_rwstat(sf, pd, &sum); return __blkg_prfill_rwstat(sf, pd, &sum);
@ -975,15 +975,13 @@ static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf, static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
struct blkg_policy_data *pd, int off) struct blkg_policy_data *pd, int off)
{ {
struct blkg_rwstat tmp; struct blkg_rwstat_sample tmp;
u64 sum;
blkg_rwstat_recursive_sum(pd->blkg, NULL, blkg_rwstat_recursive_sum(pd->blkg, NULL,
offsetof(struct blkcg_gq, stat_bytes), &tmp); offsetof(struct blkcg_gq, stat_bytes), &tmp);
sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
return __blkg_prfill_u64(sf, pd, sum >> 9); return __blkg_prfill_u64(sf, pd,
(tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE]) >> 9);
} }
static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v) static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)

39
block/blk-cgroup.c
View File

@ -544,7 +544,7 @@ EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
* Print @rwstat to @sf for the device assocaited with @pd. * Print @rwstat to @sf for the device assocaited with @pd.
*/ */
u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
const struct blkg_rwstat *rwstat) const struct blkg_rwstat_sample *rwstat)
{ {
static const char *rwstr[] = { static const char *rwstr[] = {
[BLKG_RWSTAT_READ] = "Read", [BLKG_RWSTAT_READ] = "Read",
@ -562,12 +562,12 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
for (i = 0; i < BLKG_RWSTAT_NR; i++) for (i = 0; i < BLKG_RWSTAT_NR; i++)
seq_printf(sf, "%s %s %llu\n", dname, rwstr[i], seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
(unsigned long long)atomic64_read(&rwstat->aux_cnt[i])); rwstat->cnt[i]);
v = atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_READ]) + v = rwstat->cnt[BLKG_RWSTAT_READ] +
atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]) + rwstat->cnt[BLKG_RWSTAT_WRITE] +
atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_DISCARD]); rwstat->cnt[BLKG_RWSTAT_DISCARD];
seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v); seq_printf(sf, "%s Total %llu\n", dname, v);
return v; return v;
} }
EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
@ -597,7 +597,7 @@ EXPORT_SYMBOL_GPL(blkg_prfill_stat);
u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
int off) int off)
{ {
struct blkg_rwstat rwstat = { }; struct blkg_rwstat_sample rwstat = { };
blkg_rwstat_read((void *)pd + off, &rwstat); blkg_rwstat_read((void *)pd + off, &rwstat);
return __blkg_prfill_rwstat(sf, pd, &rwstat); return __blkg_prfill_rwstat(sf, pd, &rwstat);
@ -607,7 +607,7 @@ EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
static u64 blkg_prfill_rwstat_field(struct seq_file *sf, static u64 blkg_prfill_rwstat_field(struct seq_file *sf,
struct blkg_policy_data *pd, int off) struct blkg_policy_data *pd, int off)
{ {
struct blkg_rwstat rwstat = { }; struct blkg_rwstat_sample rwstat = { };
blkg_rwstat_read((void *)pd->blkg + off, &rwstat); blkg_rwstat_read((void *)pd->blkg + off, &rwstat);
return __blkg_prfill_rwstat(sf, pd, &rwstat); return __blkg_prfill_rwstat(sf, pd, &rwstat);
@ -651,7 +651,7 @@ static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf,
struct blkg_policy_data *pd, struct blkg_policy_data *pd,
int off) int off)
{ {
struct blkg_rwstat rwstat; struct blkg_rwstat_sample rwstat;
blkg_rwstat_recursive_sum(pd->blkg, NULL, off, &rwstat); blkg_rwstat_recursive_sum(pd->blkg, NULL, off, &rwstat);
return __blkg_prfill_rwstat(sf, pd, &rwstat); return __blkg_prfill_rwstat(sf, pd, &rwstat);
@ -734,7 +734,7 @@ EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
* @blkg: blkg of interest * @blkg: blkg of interest
* @pol: blkcg_policy which contains the blkg_rwstat * @pol: blkcg_policy which contains the blkg_rwstat
* @off: offset to the blkg_rwstat in blkg_policy_data or @blkg * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
* @sum: blkg_rwstat structure containing the results * @sum: blkg_rwstat_sample structure containing the results
* *
* Collect the blkg_rwstat specified by @blkg, @pol and @off and all its * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its
* online descendants and their aux counts. The caller must be holding the * online descendants and their aux counts. The caller must be holding the
@ -744,7 +744,7 @@ EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
* is at @off bytes into @blkg's blkg_policy_data of the policy. * is at @off bytes into @blkg's blkg_policy_data of the policy.
*/ */
void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol, void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol,
int off, struct blkg_rwstat *sum) int off, struct blkg_rwstat_sample *sum)
{ {
struct blkcg_gq *pos_blkg; struct blkcg_gq *pos_blkg;
struct cgroup_subsys_state *pos_css; struct cgroup_subsys_state *pos_css;
@ -765,8 +765,7 @@ void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol,
rwstat = (void *)pos_blkg + off; rwstat = (void *)pos_blkg + off;
for (i = 0; i < BLKG_RWSTAT_NR; i++) for (i = 0; i < BLKG_RWSTAT_NR; i++)
atomic64_set(&sum->aux_cnt[i], sum->cnt[i] = blkg_rwstat_read_counter(rwstat, i);
blkg_rwstat_read_counter(rwstat, i));
} }
rcu_read_unlock(); rcu_read_unlock();
} }
@ -934,7 +933,7 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
const char *dname; const char *dname;
char *buf; char *buf;
struct blkg_rwstat rwstat; struct blkg_rwstat_sample rwstat;
u64 rbytes, wbytes, rios, wios, dbytes, dios; u64 rbytes, wbytes, rios, wios, dbytes, dios;
size_t size = seq_get_buf(sf, &buf), off = 0; size_t size = seq_get_buf(sf, &buf), off = 0;
int i; int i;
@ -956,15 +955,15 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
blkg_rwstat_recursive_sum(blkg, NULL, blkg_rwstat_recursive_sum(blkg, NULL,
offsetof(struct blkcg_gq, stat_bytes), &rwstat); offsetof(struct blkcg_gq, stat_bytes), &rwstat);
rbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]); rbytes = rwstat.cnt[BLKG_RWSTAT_READ];
wbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]); wbytes = rwstat.cnt[BLKG_RWSTAT_WRITE];
dbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]); dbytes = rwstat.cnt[BLKG_RWSTAT_DISCARD];
blkg_rwstat_recursive_sum(blkg, NULL, blkg_rwstat_recursive_sum(blkg, NULL,
offsetof(struct blkcg_gq, stat_ios), &rwstat); offsetof(struct blkcg_gq, stat_ios), &rwstat);
rios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]); rios = rwstat.cnt[BLKG_RWSTAT_READ];
wios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]); wios = rwstat.cnt[BLKG_RWSTAT_WRITE];
dios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]); dios = rwstat.cnt[BLKG_RWSTAT_DISCARD];
spin_unlock_irq(&blkg->q->queue_lock); spin_unlock_irq(&blkg->q->queue_lock);

22
include/linux/blk-cgroup.h
View File

@ -63,8 +63,7 @@ struct blkcg {
/* /*
* blkg_[rw]stat->aux_cnt is excluded for local stats but included for * blkg_[rw]stat->aux_cnt is excluded for local stats but included for
* recursive. Used to carry stats of dead children, and, for blkg_rwstat, * recursive. Used to carry stats of dead children.
* to carry result values from read and sum operations.
*/ */
struct blkg_stat { struct blkg_stat {
struct percpu_counter cpu_cnt; struct percpu_counter cpu_cnt;
@ -76,6 +75,10 @@ struct blkg_rwstat {
atomic64_t aux_cnt[BLKG_RWSTAT_NR]; atomic64_t aux_cnt[BLKG_RWSTAT_NR];
}; };
struct blkg_rwstat_sample {
u64 cnt[BLKG_RWSTAT_NR];
};
/* /*
* A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
* request_queue (q). This is used by blkcg policies which need to track * request_queue (q). This is used by blkcg policies which need to track
@ -213,7 +216,7 @@ void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
bool show_total); bool show_total);
u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v); u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
const struct blkg_rwstat *rwstat); const struct blkg_rwstat_sample *rwstat);
u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off); u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
int off); int off);
@ -225,7 +228,7 @@ int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v);
u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg, u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
struct blkcg_policy *pol, int off); struct blkcg_policy *pol, int off);
void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol, void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol,
int off, struct blkg_rwstat *sum); int off, struct blkg_rwstat_sample *sum);
struct blkg_conf_ctx { struct blkg_conf_ctx {
struct gendisk *disk; struct gendisk *disk;
@ -701,13 +704,13 @@ static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
* Read the current snapshot of @rwstat and return it in the aux counts. * Read the current snapshot of @rwstat and return it in the aux counts.
*/ */
static inline void blkg_rwstat_read(struct blkg_rwstat *rwstat, static inline void blkg_rwstat_read(struct blkg_rwstat *rwstat,
struct blkg_rwstat *result) struct blkg_rwstat_sample *result)
{ {
int i; int i;
for (i = 0; i < BLKG_RWSTAT_NR; i++) for (i = 0; i < BLKG_RWSTAT_NR; i++)
atomic64_set(&result->aux_cnt[i], result->cnt[i] =
percpu_counter_sum_positive(&rwstat->cpu_cnt[i])); percpu_counter_sum_positive(&rwstat->cpu_cnt[i]);
} }
/** /**
@ -720,11 +723,10 @@ static inline void blkg_rwstat_read(struct blkg_rwstat *rwstat,
*/ */
static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat) static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
{ {
struct blkg_rwstat tmp = { }; struct blkg_rwstat_sample tmp = { };
blkg_rwstat_read(rwstat, &tmp); blkg_rwstat_read(rwstat, &tmp);
return atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) + return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
} }
/** /**