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authorJosef Bacik <jbacik@fb.com>2018-07-03 18:14:52 +0300
committerJens Axboe <axboe@kernel.dk>2018-07-09 18:07:54 +0300
commit903d23f0a354f226fa78f1c1c34b60aaf992e812 (patch)
treec74a26a70450653725e8d5bf25a77eb56586f245 /block/blk-cgroup.c
parentc7c98fd37653955d3a17dd4f1fa67aba070096a9 (diff)
downloadlinux-903d23f0a354f226fa78f1c1c34b60aaf992e812.tar.xz
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>
Diffstat (limited to 'block/blk-cgroup.c')
-rw-r--r--block/blk-cgroup.c47
1 files changed, 44 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 @@ 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");