From: Robin Dong <san...@taobao.com>
Currently, if the IO is throttled by io-throttle, the SA has no idea of
the situation and can't report it to the real application user about
that he/she has to do something. So this patch adds a new interface
named blkio.throttle.io_queued which indicates how many IOs are
currently throttled.
The nr_queued[] of struct throtl_grp is of type "unsigned int" and updates
to it are atomic both at 32bit and 64bit platforms, so we could just
read tg->nr_queued only under blkcg->lock.
Changelog from v2:
Use nr-queued[] of struct throtl_grp for stats instaed of adding new
blkg_rwstat.
Cc: Tejun Heo <t...@kernel.org>
Cc: Vivek Goyal <vgo...@redhat.com>
Cc: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Tao Ma <boyu...@taobao.com>
Signed-off-by: Robin Dong <san...@taobao.com>
---
block/blk-throttle.c | 40 ++++++++++++++++++++++++++++++++++++++++
1 files changed, 40 insertions(+), 0 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index a9664fa..e410448 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -953,6 +953,32 @@ static u64 tg_prfill_cpu_rwstat(struct seq_file *sf,
return __blkg_prfill_rwstat(sf, pd, &rwstat);
}
+static u64 tg_prfill_io_queued(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
+{
+ static const char *rwstr[] = {
+ [READ] = "Read",
+ [WRITE] = "Write",
+ };
+ struct throtl_grp *tg = pd_to_tg(pd);
+ const char *dname = NULL;
+ unsigned int v;
+ int i;
+
+ if (pd->blkg->q->backing_dev_info.dev)
+ dname = dev_name(pd->blkg->q->backing_dev_info.dev);
+
+ if (!dname)
+ return 0;
+
+ for (i = 0; i <= WRITE; i++)
+ seq_printf(sf, "%s %s %u\n", dname, rwstr[i], tg->nr_queued[i]);
+
+ v = tg->nr_queued[READ] + tg->nr_queued[WRITE];
+ seq_printf(sf, "%s Total %u\n", dname, v);
+ return v;
+}
+
static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
@@ -963,6 +989,16 @@ static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct
cftype *cft,
return 0;
}
+static int tg_print_io_queued(struct cgroup *cgrp, struct cftype *cft,
+ struct seq_file *sf)
+{
+ struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
+
+ blkcg_print_blkgs(sf, blkcg, tg_prfill_io_queued, &blkcg_policy_throtl,
+ cft->private, true);
+ return 0;
+}
+
static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,
int off)
{
@@ -1085,6 +1121,10 @@ static struct cftype throtl_files[] = {
.private = offsetof(struct tg_stats_cpu, serviced),
.read_seq_string = tg_print_cpu_rwstat,
},
+ {
+ .name = "throttle.io_queued",
+ .read_seq_string = tg_print_io_queued,
+ },
{ } /* terminate */
};
--
1.7.1
--
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