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block: use ktime_get_ns() instead of sched_clock() for cfq and bfq

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cfq and bfq have some internal fields that use sched_clock() which can
trivially use ktime_get_ns() instead. Their timestamp fields in struct
request can also use ktime_get_ns(), which resolves the 8 year old
comment added by commit 28f4197e5d ("block: disable preemption before
using sched_clock()").

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Omar Sandoval 2018-05-09 02:08:51 -07:00 committed by Jens Axboe
parent 544ccc8dc9
commit 84c7afcebe
4 changed files with 57 additions and 63 deletions
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40
block/bfq-cgroup.c
View File

@ -55,13 +55,13 @@ BFQG_FLAG_FNS(empty)
/* This should be called with the scheduler lock held. */
static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
{
unsigned long long now;
u64 now;
if (!bfqg_stats_waiting(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_group_wait_time))
now = ktime_get_ns();
if (now > stats->start_group_wait_time)
blkg_stat_add(&stats->group_wait_time,
now - stats->start_group_wait_time);
bfqg_stats_clear_waiting(stats);
@ -77,20 +77,20 @@ static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
return;
if (bfqg == curr_bfqg)
return;
stats->start_group_wait_time = sched_clock();
stats->start_group_wait_time = ktime_get_ns();
bfqg_stats_mark_waiting(stats);
}
/* This should be called with the scheduler lock held. */
static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
{
unsigned long long now;
u64 now;
if (!bfqg_stats_empty(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_empty_time))
now = ktime_get_ns();
if (now > stats->start_empty_time)
blkg_stat_add(&stats->empty_time,
now - stats->start_empty_time);
bfqg_stats_clear_empty(stats);
@ -116,7 +116,7 @@ void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
if (bfqg_stats_empty(stats))
return;
stats->start_empty_time = sched_clock();
stats->start_empty_time = ktime_get_ns();
bfqg_stats_mark_empty(stats);
}
@ -125,9 +125,9 @@ void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
struct bfqg_stats *stats = &bfqg->stats;
if (bfqg_stats_idling(stats)) {
unsigned long long now = sched_clock();
u64 now = ktime_get_ns();
if (time_after64(now, stats->start_idle_time))
if (now > stats->start_idle_time)
blkg_stat_add(&stats->idle_time,
now - stats->start_idle_time);
bfqg_stats_clear_idling(stats);
@ -138,7 +138,7 @@ void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
{
struct bfqg_stats *stats = &bfqg->stats;
stats->start_idle_time = sched_clock();
stats->start_idle_time = ktime_get_ns();
bfqg_stats_mark_idling(stats);
}
@ -171,18 +171,18 @@ void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op)
blkg_rwstat_add(&bfqg->stats.merged, op, 1);
}
void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
uint64_t io_start_time, unsigned int op)
void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
u64 io_start_time_ns, unsigned int op)
{
struct bfqg_stats *stats = &bfqg->stats;
unsigned long long now = sched_clock();
u64 now = ktime_get_ns();
if (time_after64(now, io_start_time))
if (now > io_start_time_ns)
blkg_rwstat_add(&stats->service_time, op,
now - io_start_time);
if (time_after64(io_start_time, start_time))
now - io_start_time_ns);
if (io_start_time_ns > start_time_ns)
blkg_rwstat_add(&stats->wait_time, op,
io_start_time - start_time);
io_start_time_ns - start_time_ns);
}
#else /* CONFIG_BFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
@ -191,8 +191,8 @@ void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
unsigned int op) { }
void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { }
void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { }
void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
uint64_t io_start_time, unsigned int op) { }
void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
u64 io_start_time_ns, unsigned int op) { }
void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }

10
block/bfq-iosched.h
View File

@ -732,9 +732,9 @@ struct bfqg_stats {
/* total time with empty current active q with other requests queued */
struct blkg_stat empty_time;
/* fields after this shouldn't be cleared on stat reset */
uint64_t start_group_wait_time;
uint64_t start_idle_time;
uint64_t start_empty_time;
u64 start_group_wait_time;
u64 start_idle_time;
u64 start_empty_time;
uint16_t flags;
#endif /* CONFIG_BFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
};
@ -856,8 +856,8 @@ void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
unsigned int op);
void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
uint64_t io_start_time, unsigned int op);
void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
u64 io_start_time_ns, unsigned int op);
void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
void bfqg_stats_update_idle_time(struct bfq_group *bfqg);

49
block/cfq-iosched.c
View File

@ -210,9 +210,9 @@ struct cfqg_stats {
/* total time with empty current active q with other requests queued */
struct blkg_stat empty_time;
/* fields after this shouldn't be cleared on stat reset */
uint64_t start_group_wait_time;
uint64_t start_idle_time;
uint64_t start_empty_time;
u64 start_group_wait_time;
u64 start_idle_time;
u64 start_empty_time;
uint16_t flags;
#endif /* CONFIG_DEBUG_BLK_CGROUP */
#endif /* CONFIG_CFQ_GROUP_IOSCHED */
@ -491,13 +491,13 @@ CFQG_FLAG_FNS(empty)
/* This should be called with the queue_lock held. */
static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
{
unsigned long long now;
u64 now;
if (!cfqg_stats_waiting(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_group_wait_time))
now = ktime_get_ns();
if (now > stats->start_group_wait_time)
blkg_stat_add(&stats->group_wait_time,
now - stats->start_group_wait_time);
cfqg_stats_clear_waiting(stats);
@ -513,20 +513,20 @@ static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
return;
if (cfqg == curr_cfqg)
return;
stats->start_group_wait_time = sched_clock();
stats->start_group_wait_time = ktime_get_ns();
cfqg_stats_mark_waiting(stats);
}
/* This should be called with the queue_lock held. */
static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
{
unsigned long long now;
u64 now;
if (!cfqg_stats_empty(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_empty_time))
now = ktime_get_ns();
if (now > stats->start_empty_time)
blkg_stat_add(&stats->empty_time,
now - stats->start_empty_time);
cfqg_stats_clear_empty(stats);
@ -552,7 +552,7 @@ static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
if (cfqg_stats_empty(stats))
return;
stats->start_empty_time = sched_clock();
stats->start_empty_time = ktime_get_ns();
cfqg_stats_mark_empty(stats);
}
@ -561,9 +561,9 @@ static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
struct cfqg_stats *stats = &cfqg->stats;
if (cfqg_stats_idling(stats)) {
unsigned long long now = sched_clock();
u64 now = ktime_get_ns();
if (time_after64(now, stats->start_idle_time))
if (now > stats->start_idle_time)
blkg_stat_add(&stats->idle_time,
now - stats->start_idle_time);
cfqg_stats_clear_idling(stats);
@ -576,7 +576,7 @@ static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
BUG_ON(cfqg_stats_idling(stats));
stats->start_idle_time = sched_clock();
stats->start_idle_time = ktime_get_ns();
cfqg_stats_mark_idling(stats);
}
@ -701,17 +701,19 @@ static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
}
static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
uint64_t start_time, uint64_t io_start_time,
unsigned int op)
u64 start_time_ns,
u64 io_start_time_ns,
unsigned int op)
{
struct cfqg_stats *stats = &cfqg->stats;
unsigned long long now = sched_clock();
u64 now = ktime_get_ns();
if (time_after64(now, io_start_time))
blkg_rwstat_add(&stats->service_time, op, now - io_start_time);
if (time_after64(io_start_time, start_time))
if (now > io_start_time_ns)
blkg_rwstat_add(&stats->service_time, op,
now - io_start_time_ns);
if (io_start_time_ns > start_time_ns)
blkg_rwstat_add(&stats->wait_time, op,
io_start_time - start_time);
io_start_time_ns - start_time_ns);
}
/* @stats = 0 */
@ -797,8 +799,9 @@ static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg,
static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
unsigned int op) { }
static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
uint64_t start_time, uint64_t io_start_time,
unsigned int op) { }
u64 start_time_ns,
u64 io_start_time_ns,
unsigned int op) { }
#endif /* CONFIG_CFQ_GROUP_IOSCHED */

21
include/linux/blkdev.h
View File

@ -1799,42 +1799,33 @@ int kblockd_schedule_work_on(int cpu, struct work_struct *work);
int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, unsigned long delay);
#ifdef CONFIG_BLK_CGROUP
/*
* This should not be using sched_clock(). A real patch is in progress
* to fix this up, until that is in place we need to disable preemption
* around sched_clock() in this function and set_io_start_time_ns().
*/
static inline void set_start_time_ns(struct request *req)
{
preempt_disable();
req->cgroup_start_time_ns = sched_clock();
preempt_enable();
req->cgroup_start_time_ns = ktime_get_ns();
}
static inline void set_io_start_time_ns(struct request *req)
{
preempt_disable();
req->cgroup_io_start_time_ns = sched_clock();
preempt_enable();
req->cgroup_io_start_time_ns = ktime_get_ns();
}
static inline uint64_t rq_start_time_ns(struct request *req)
static inline u64 rq_start_time_ns(struct request *req)
{
return req->cgroup_start_time_ns;
}
static inline uint64_t rq_io_start_time_ns(struct request *req)
static inline u64 rq_io_start_time_ns(struct request *req)
{
return req->cgroup_io_start_time_ns;
}
#else
static inline void set_start_time_ns(struct request *req) {}
static inline void set_io_start_time_ns(struct request *req) {}
static inline uint64_t rq_start_time_ns(struct request *req)
static inline u64 rq_start_time_ns(struct request *req)
{
return 0;
}
static inline uint64_t rq_io_start_time_ns(struct request *req)
static inline u64 rq_io_start_time_ns(struct request *req)
{
return 0;
}