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blkcg: Track DISCARD statistics and output them in cgroup io.stat

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Add tracking of REQ_OP_DISCARD ios to the per-cgroup io.stat.  Two
fields, dbytes and dios, to respectively count the total bytes and
number of discards are added.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andy Newell <newella@fb.com>
Cc: Michael Callahan <michaelcallahan@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2018-07-18 04:47:41 -07:00 committed by Jens Axboe
parent bdca3c87fb
commit 636620b66d
3 changed files with 19 additions and 9 deletions
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10
Documentation/admin-guide/cgroup-v2.rst
View File

@ -1317,17 +1317,19 @@ IO Interface Files
Lines are keyed by $MAJ:$MIN device numbers and not ordered.
The following nested keys are defined.
====== ===================
====== =====================
rbytes Bytes read
wbytes Bytes written
rios Number of read IOs
wios Number of write IOs
====== ===================
dbytes Bytes discarded
dios Number of discard IOs
====== =====================
An example read output follows:
8:16 rbytes=1459200 wbytes=314773504 rios=192 wios=353
8:0 rbytes=90430464 wbytes=299008000 rios=8950 wios=1252
8:16 rbytes=1459200 wbytes=314773504 rios=192 wios=353 dbytes=0 dios=0
8:0 rbytes=90430464 wbytes=299008000 rios=8950 wios=1252 dbytes=50331648 dios=3021
io.weight
A read-write flat-keyed file which exists on non-root cgroups.

13
block/blk-cgroup.c
View File

@ -567,6 +567,7 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
[BLKG_RWSTAT_WRITE] = "Write",
[BLKG_RWSTAT_SYNC] = "Sync",
[BLKG_RWSTAT_ASYNC] = "Async",
[BLKG_RWSTAT_DISCARD] = "Discard",
};
const char *dname = blkg_dev_name(pd->blkg);
u64 v;
@ -580,7 +581,8 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
(unsigned long long)atomic64_read(&rwstat->aux_cnt[i]));
v = atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_READ]) +
atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]);
atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]) +
atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_DISCARD]);
seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);
return v;
}
@ -959,7 +961,7 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
const char *dname;
char *buf;
struct blkg_rwstat rwstat;
u64 rbytes, wbytes, rios, wios;
u64 rbytes, wbytes, rios, wios, dbytes, dios;
size_t size = seq_get_buf(sf, &buf), off = 0;
int i;
bool has_stats = false;
@ -982,19 +984,22 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
offsetof(struct blkcg_gq, stat_bytes));
rbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
wbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
dbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]);
rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
offsetof(struct blkcg_gq, stat_ios));
rios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]);
wios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]);
dios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]);
spin_unlock_irq(blkg->q->queue_lock);
if (rbytes || wbytes || rios || wios) {
has_stats = true;
off += scnprintf(buf+off, size-off,
"rbytes=%llu wbytes=%llu rios=%llu wios=%llu",
rbytes, wbytes, rios, wios);
"rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu",
rbytes, wbytes, rios, wios,
dbytes, dios);
}
if (!blkcg_debug_stats)

5
include/linux/blk-cgroup.h
View File

@ -35,6 +35,7 @@ enum blkg_rwstat_type {
BLKG_RWSTAT_WRITE,
BLKG_RWSTAT_SYNC,
BLKG_RWSTAT_ASYNC,
BLKG_RWSTAT_DISCARD,
BLKG_RWSTAT_NR,
BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
@ -649,7 +650,9 @@ static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
{
struct percpu_counter *cnt;
if (op_is_write(op))
if (op_is_discard(op))
cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_DISCARD];
else if (op_is_write(op))
cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_WRITE];
else
cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_READ];