From: Robin Dong <san...@taobao.com>
Currently, if the IO is throttled by io-throttle, the system admin 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
exposes the number of bios that have been sent to blk-throttle therefore the
user could calculate the difference from throttle.io_serviced to see how many
IOs are currently throttled.
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>
---
v3 <-- v2:
- Use nr-queued[] of struct throtl_grp for stats instaed of adding new
blkg_rwstat.
v4 <-- v3:
- Add two new blkg_rwstat arguments to count total bios be sent in
blk_throttle.
block/blk-throttle.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 44 insertions(+), 0 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 46ddeff..b122b0c 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -70,6 +70,10 @@ struct throtl_grp {
/* Number of queued bios on READ and WRITE lists */
unsigned int nr_queued[2];
+ /* The stats of total number queued in blk-throtlle */
+ struct blkg_rwstat io_queue_bytes;
+ struct blkg_rwstat io_queued;
+
/* bytes per second rate limits */
uint64_t bps[2];
@@ -267,6 +271,8 @@ static void throtl_pd_reset_stats(struct blkcg_gq *blkg)
blkg_rwstat_reset(&sc->service_bytes);
blkg_rwstat_reset(&sc->serviced);
}
+ blkg_rwstat_reset(&tg->io_queued);
+ blkg_rwstat_reset(&tg->io_queue_bytes);
}
static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td,
@@ -699,6 +705,12 @@ static void throtl_update_dispatch_stats(struct throtl_grp
*tg, u64 bytes,
local_irq_restore(flags);
}
+static void throtl_update_queued_stats(struct throtl_grp *tg, u64 bytes, int
rw)
+{
+ blkg_rwstat_add(&tg->io_queued, rw, 1);
+ blkg_rwstat_add(&tg->io_queue_bytes, rw, bytes);
+}
+
static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
{
bool rw = bio_data_dir(bio);
@@ -952,6 +964,15 @@ 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)
+{
+ struct throtl_grp *tg = pd_to_tg(pd);
+ struct blkg_rwstat *rwstat = (void *)tg + off;
+
+ return __blkg_prfill_rwstat(sf, pd, rwstat);
+}
+
static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
struct seq_file *sf)
{
@@ -962,6 +983,16 @@ 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)
{
@@ -1084,6 +1115,16 @@ static struct cftype throtl_files[] = {
.private = offsetof(struct tg_stats_cpu, serviced),
.read_seq_string = tg_print_cpu_rwstat,
},
+ {
+ .name = "throttle.io_queue_bytes",
+ .private = offsetof(struct throtl_grp, io_queue_bytes),
+ .read_seq_string = tg_print_io_queued,
+ },
+ {
+ .name = "throttle.io_queued",
+ .private = offsetof(struct throtl_grp, io_queued),
+ .read_seq_string = tg_print_io_queued,
+ },
{ } /* terminate */
};
@@ -1128,6 +1169,8 @@ bool blk_throtl_bio(struct request_queue *q, struct bio
*bio)
if (tg_no_rule_group(tg, rw)) {
throtl_update_dispatch_stats(tg,
bio->bi_size, bio->bi_rw);
+ throtl_update_queued_stats(tg,
+ bio->bi_size, bio->bi_rw);
goto out_unlock_rcu;
}
}
@@ -1141,6 +1184,7 @@ bool blk_throtl_bio(struct request_queue *q, struct bio
*bio)
if (unlikely(!tg))
goto out_unlock;
+ throtl_update_queued_stats(tg, bio->bi_size, bio->bi_rw);
if (tg->nr_queued[rw]) {
/*
* There is already another bio queued in same dir. No
--
1.7.1
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