block: consolidate struct request timestamp fields
Currently, struct request has four timestamp fields:
- A start time, set at get_request time, in jiffies, used for iostats
- An I/O start time, set at start_request time, in ktime nanoseconds,
used for blk-stats (i.e., wbt, kyber, hybrid polling)
- Another start time and another I/O start time, used for cfq and bfq
These can all be consolidated into one start time and one I/O start
time, both in ktime nanoseconds, shaving off up to 16 bytes from struct
request depending on the kernel config.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 771ae97..ebc264c 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -4778,8 +4778,8 @@ static void bfq_finish_requeue_request(struct request *rq)
if (rq->rq_flags & RQF_STARTED)
bfqg_stats_update_completion(bfqq_group(bfqq),
- rq_start_time_ns(rq),
- rq_io_start_time_ns(rq),
+ rq->start_time_ns,
+ rq->io_start_time_ns,
rq->cmd_flags);
if (likely(rq->rq_flags & RQF_STARTED)) {
diff --git a/block/blk-core.c b/block/blk-core.c
index 33d5c7d..1418a1c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -196,8 +196,7 @@ void blk_rq_init(struct request_queue *q, struct request *rq)
RB_CLEAR_NODE(&rq->rb_node);
rq->tag = -1;
rq->internal_tag = -1;
- rq->start_time = jiffies;
- set_start_time_ns(rq);
+ rq->start_time_ns = ktime_get_ns();
rq->part = NULL;
seqcount_init(&rq->gstate_seq);
u64_stats_init(&rq->aborted_gstate_sync);
@@ -2726,7 +2725,7 @@ void blk_account_io_completion(struct request *req, unsigned int bytes)
}
}
-void blk_account_io_done(struct request *req)
+void blk_account_io_done(struct request *req, u64 now)
{
/*
* Account IO completion. flush_rq isn't accounted as a
@@ -2734,11 +2733,12 @@ void blk_account_io_done(struct request *req)
* containing request is enough.
*/
if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) {
- unsigned long duration = jiffies - req->start_time;
+ unsigned long duration;
const int rw = rq_data_dir(req);
struct hd_struct *part;
int cpu;
+ duration = nsecs_to_jiffies(now - req->start_time_ns);
cpu = part_stat_lock();
part = req->part;
@@ -2969,10 +2969,8 @@ static void blk_dequeue_request(struct request *rq)
* and to it is freed is accounted as io that is in progress at
* the driver side.
*/
- if (blk_account_rq(rq)) {
+ if (blk_account_rq(rq))
q->in_flight[rq_is_sync(rq)]++;
- set_io_start_time_ns(rq);
- }
}
/**
@@ -3192,12 +3190,13 @@ EXPORT_SYMBOL_GPL(blk_unprep_request);
void blk_finish_request(struct request *req, blk_status_t error)
{
struct request_queue *q = req->q;
+ u64 now = ktime_get_ns();
lockdep_assert_held(req->q->queue_lock);
WARN_ON_ONCE(q->mq_ops);
if (req->rq_flags & RQF_STATS)
- blk_stat_add(req);
+ blk_stat_add(req, now);
if (req->rq_flags & RQF_QUEUED)
blk_queue_end_tag(q, req);
@@ -3212,7 +3211,7 @@ void blk_finish_request(struct request *req, blk_status_t error)
if (req->rq_flags & RQF_DONTPREP)
blk_unprep_request(req);
- blk_account_io_done(req);
+ blk_account_io_done(req, now);
if (req->end_io) {
wbt_done(req->q->rq_wb, req);
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 782940c..5573d0f 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -724,13 +724,12 @@ static struct request *attempt_merge(struct request_queue *q,
}
/*
- * At this point we have either done a back merge
- * or front merge. We need the smaller start_time of
- * the merged requests to be the current request
- * for accounting purposes.
+ * At this point we have either done a back merge or front merge. We
+ * need the smaller start_time_ns of the merged requests to be the
+ * current request for accounting purposes.
*/
- if (time_after(req->start_time, next->start_time))
- req->start_time = next->start_time;
+ if (next->start_time_ns < req->start_time_ns)
+ req->start_time_ns = next->start_time_ns;
req->biotail->bi_next = next->bio;
req->biotail = next->biotail;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 39b4e98..4e9d835 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -309,7 +309,7 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
RB_CLEAR_NODE(&rq->rb_node);
rq->rq_disk = NULL;
rq->part = NULL;
- rq->start_time = jiffies;
+ rq->start_time_ns = ktime_get_ns();
rq->io_start_time_ns = 0;
rq->nr_phys_segments = 0;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
@@ -329,8 +329,6 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
#ifdef CONFIG_BLK_CGROUP
rq->rl = NULL;
- set_start_time_ns(rq);
- rq->cgroup_io_start_time_ns = 0;
#endif
data->ctx->rq_dispatched[op_is_sync(op)]++;
@@ -506,12 +504,14 @@ EXPORT_SYMBOL_GPL(blk_mq_free_request);
inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
{
+ u64 now = ktime_get_ns();
+
if (rq->rq_flags & RQF_STATS) {
blk_mq_poll_stats_start(rq->q);
- blk_stat_add(rq);
+ blk_stat_add(rq, now);
}
- blk_account_io_done(rq);
+ blk_account_io_done(rq, now);
if (rq->end_io) {
wbt_done(rq->q->rq_wb, rq);
diff --git a/block/blk-stat.c b/block/blk-stat.c
index 725a881..175c143 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -47,15 +47,14 @@ static void __blk_stat_add(struct blk_rq_stat *stat, u64 value)
stat->nr_samples++;
}
-void blk_stat_add(struct request *rq)
+void blk_stat_add(struct request *rq, u64 now)
{
struct request_queue *q = rq->q;
struct blk_stat_callback *cb;
struct blk_rq_stat *stat;
int bucket;
- u64 now, value;
+ u64 value;
- now = ktime_get_ns();
value = (now >= rq->io_start_time_ns) ? now - rq->io_start_time_ns : 0;
blk_throtl_stat_add(rq, value);
diff --git a/block/blk-stat.h b/block/blk-stat.h
index 17c812d..78399cd 100644
--- a/block/blk-stat.h
+++ b/block/blk-stat.h
@@ -65,7 +65,7 @@ struct blk_stat_callback {
struct blk_queue_stats *blk_alloc_queue_stats(void);
void blk_free_queue_stats(struct blk_queue_stats *);
-void blk_stat_add(struct request *);
+void blk_stat_add(struct request *rq, u64 now);
/* record time/size info in request but not add a callback */
void blk_stat_enable_accounting(struct request_queue *q);
diff --git a/block/blk.h b/block/blk.h
index b034fd2..eaf1a8e 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -186,7 +186,7 @@ unsigned int blk_plug_queued_count(struct request_queue *q);
void blk_account_io_start(struct request *req, bool new_io);
void blk_account_io_completion(struct request *req, unsigned int bytes);
-void blk_account_io_done(struct request *req);
+void blk_account_io_done(struct request *req, u64 now);
/*
* EH timer and IO completion will both attempt to 'grab' the request, make
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 652ca06..6b9f6b1 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -4228,8 +4228,8 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
cfqd->rq_in_driver--;
cfqq->dispatched--;
(RQ_CFQG(rq))->dispatched--;
- cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
- rq_io_start_time_ns(rq), rq->cmd_flags);
+ cfqg_stats_update_completion(cfqq->cfqg, rq->start_time_ns,
+ rq->io_start_time_ns, rq->cmd_flags);
cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
@@ -4245,16 +4245,7 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
cfqq_type(cfqq));
st->ttime.last_end_request = now;
- /*
- * We have to do this check in jiffies since start_time is in
- * jiffies and it is not trivial to convert to ns. If
- * cfq_fifo_expire[1] ever comes close to 1 jiffie, this test
- * will become problematic but so far we are fine (the default
- * is 128 ms).
- */
- if (!time_after(rq->start_time +
- nsecs_to_jiffies(cfqd->cfq_fifo_expire[1]),
- jiffies))
+ if (rq->start_time_ns + cfqd->cfq_fifo_expire[1] <= now)
cfqd->last_delayed_sync = now;
}