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blk-cgroup: allow controllers to output their own stats 

blk-iolatency has a few stats that it would like to print out, and
instead of adding a bunch of crap to the generic code just provide a
helper so that controllers can add stuff to the stat line if they want
to.

Hide it behind a boot option since it changes the output of io.stat from
normal, and these stats are only interesting to developers.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Josef Bacik 2018-07-03 11:14:52 -04:00 committed by Jens Axboe
parent c7c98fd376
commit 903d23f0a3
2 changed files with 47 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
block/blk-cgroup.c
View File

@ -50,6 +50,8 @@ static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */
static bool blkcg_debug_stats = false;
static bool blkcg_policy_enabled(struct request_queue *q,
const struct blkcg_policy *pol)
{
@ -954,13 +956,25 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
const char *dname;
char *buf;
struct blkg_rwstat rwstat;
u64 rbytes, wbytes, rios, wios;
size_t size = seq_get_buf(sf, &buf), off = 0;
int i;
bool has_stats = false;
dname = blkg_dev_name(blkg);
if (!dname)
continue;
/*
* Hooray string manipulation, count is the size written NOT
* INCLUDING THE \0, so size is now count+1 less than what we
* had before, but we want to start writing the next bit from
* the \0 so we only add count to buf.
*/
off += scnprintf(buf+off, size-off, "%s ", dname);
spin_lock_irq(blkg->q->queue_lock);
rwstat = blkg_rwstat_recursive_sum(blkg, NULL,
@ -975,9 +989,33 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
spin_unlock_irq(blkg->q->queue_lock);
if (rbytes || wbytes || rios || wios)
seq_printf(sf, "%s rbytes=%llu wbytes=%llu rios=%llu wios=%llu\n",
dname, rbytes, wbytes, rios, wios);
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);
}
if (!blkcg_debug_stats)
goto next;
for (i = 0; i < BLKCG_MAX_POLS; i++) {
struct blkcg_policy *pol = blkcg_policy[i];
size_t written;
if (!blkg->pd[i] || !pol->pd_stat_fn)
continue;
written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off);
if (written)
has_stats = true;
off += written;
}
next:
if (has_stats) {
off += scnprintf(buf+off, size-off, "\n");
seq_commit(sf, off);
}
}
rcu_read_unlock();
@ -1547,3 +1585,6 @@ out_unlock:
mutex_unlock(&blkcg_pol_register_mutex);
}
EXPORT_SYMBOL_GPL(blkcg_policy_unregister);
module_param(blkcg_debug_stats, bool, 0644);
MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not");

3
include/linux/blk-cgroup.h
View File

@ -148,6 +148,8 @@ typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
typedef size_t (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd, char *buf,
size_t size);
struct blkcg_policy {
int plid;
@ -167,6 +169,7 @@ struct blkcg_policy {
blkcg_pol_offline_pd_fn *pd_offline_fn;
blkcg_pol_free_pd_fn *pd_free_fn;
blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
blkcg_pol_stat_pd_fn *pd_stat_fn;
};
extern struct blkcg blkcg_root;