From: Josef Bacik <josef@toxicpanda.com>
To: axboe@kernel.dk, kernel-team@fb.com, linux-block@vger.kernel.org,
akpm@linux-foundation.org, hannes@cmpxchg.org, tj@kernel.org,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Cc: Josef Bacik <jbacik@fb.com>
Subject: [PATCH 03/14] blk-cgroup: allow controllers to output their own stats
Date: Fri, 29 Jun 2018 15:25:31 -0400 [thread overview]
Message-ID: <20180629192542.26649-4-josef@toxicpanda.com> (raw)
In-Reply-To: <20180629192542.26649-1-josef@toxicpanda.com>
From: Josef Bacik <jbacik@fb.com>
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>
---
block/blk-cgroup.c | 47 +++++++++++++++++++++++++++++++++++++++++++---
include/linux/blk-cgroup.h | 3 +++
2 files changed, 47 insertions(+), 3 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index eb85cb87c40f..7dc6f05cc44b 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -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 @@ void blkcg_policy_unregister(struct blkcg_policy *pol)
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");
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 69aa71dc0c04..b41292726c0f 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -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;
--
2.14.3
next prev parent reply other threads:[~2018-06-29 19:25 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-29 19:25 [PATCH 00/14][V5] Introduce io.latency io controller for cgroups Josef Bacik
2018-06-29 19:25 ` [PATCH 01/14] block: add bi_blkg to the bio " Josef Bacik
2018-06-29 19:25 ` [PATCH 02/14] block: introduce bio_issue_as_root_blkg Josef Bacik
2018-06-29 19:25 ` Josef Bacik [this message]
2018-07-02 21:06 ` [PATCH 03/14] blk-cgroup: allow controllers to output their own stats Tejun Heo
2018-06-29 19:25 ` [PATCH 04/14] blk: introduce REQ_SWAP Josef Bacik
2018-07-02 21:47 ` Jens Axboe
2018-06-29 19:25 ` [PATCH 05/14] swap,blkcg: issue swap io with the appropriate context Josef Bacik
2018-06-29 19:25 ` [PATCH 06/14] blkcg: add generic throttling mechanism Josef Bacik
2018-06-29 19:25 ` [PATCH 07/14] memcontrol: schedule throttling if we are congested Josef Bacik
2018-06-29 19:25 ` [PATCH 08/14] blk-stat: export helpers for modifying blk_rq_stat Josef Bacik
2018-06-29 19:25 ` [PATCH 09/14] blk-rq-qos: refactor out common elements of blk-wbt Josef Bacik
2018-06-29 19:25 ` [PATCH 10/14] block: remove external dependency on wbt_flags Josef Bacik
2018-06-29 19:25 ` [PATCH 11/14] rq-qos: introduce dio_bio callback Josef Bacik
2018-06-29 19:25 ` [PATCH 12/14] block: introduce blk-iolatency io controller Josef Bacik
2018-07-02 21:47 ` Tejun Heo
2018-06-29 19:25 ` [PATCH 13/14] Documentation: add a doc for blk-iolatency Josef Bacik
2018-07-02 21:49 ` Tejun Heo
2018-06-29 19:25 ` [PATCH 14/14] skip readahead if the cgroup is congested Josef Bacik
2018-07-02 21:13 ` Tejun Heo
2018-07-02 21:26 ` [PATCH 00/14][V5] Introduce io.latency io controller for cgroups Andrew Morton
2018-07-02 21:38 ` Josef Bacik
2018-07-02 21:41 ` Jens Axboe
2018-07-02 21:47 ` Andrew Morton
-- strict thread matches above, loose matches on Subject: below --
2018-07-03 15:14 [PATCH 0/14][V6] " Josef Bacik
2018-07-03 15:14 ` [PATCH 03/14] blk-cgroup: allow controllers to output their own stats Josef Bacik
2018-06-27 19:09 [PATCH 00/14][V4] Introduce io.latency io controller for cgroups Josef Bacik
2018-06-27 19:09 ` [PATCH 03/14] blk-cgroup: allow controllers to output their own stats Josef Bacik
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