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Message-ID: <170873667563.1860799.16297433997512061653.stgit@frogsfrogsfrogs>
Date: Fri, 23 Feb 2024 17:10:05 -0800
From: "Darrick J. Wong" <djwong@...nel.org>
To: akpm@...ux-foundation.org, daniel@...o.nz, kent.overstreet@...ux.dev,
djwong@...nel.org
Cc: Dave Chinner <david@...morbit.com>, Theodore Ts'o <tytso@....edu>,
Coly Li <colyli@...e.de>, linux-xfs@...r.kernel.org,
linux-bcachefs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] time_stats: Promote to lib/
From: Kent Overstreet <kent.overstreet@...ux.dev>
Library code from bcachefs for tracking latency measurements.
The main interface is
time_stats_update(stats, start_time);
which collects a new event with an end time of the current time.
It features percpu buffering of input values, making it very low
overhead, and nicely formatted output to printbufs or seq_buf.
Sample output, from the bcache conversion:
root@...ia-kvm:/sys/fs/bcache/bdaedb8c-4554-4dd2-87e4-276e51eb47cc# cat internal/btree_sort_times
count: 6414
since mount recent
duration of events
min: 440 ns
max: 1102 us
total: 674 ms
mean: 105 us 102 us
stddev: 101 us 88 us
time between events
min: 881 ns
max: 3 s
mean: 7 ms 6 ms
stddev: 52 ms 6 ms
Cc: Darrick J. Wong <djwong@...nel.org>
Cc: Dave Chinner <david@...morbit.com>
Cc: Theodore Ts'o <tytso@....edu>
Cc: Coly Li <colyli@...e.de>
Signed-off-by: Kent Overstreet <kent.overstreet@...ux.dev>
Reviewed-by: Darrick J. Wong <djwong@...nel.org>
Signed-off-by: Darrick J. Wong <djwong@...nel.org>
---
MAINTAINERS | 7 +
fs/bcachefs/Kconfig | 2
fs/bcachefs/alloc_foreground.c | 13 +-
fs/bcachefs/bcachefs.h | 11 +
fs/bcachefs/btree_cache.c | 2
fs/bcachefs/btree_gc.c | 2
fs/bcachefs/btree_io.c | 8 +
fs/bcachefs/btree_iter.c | 8 +
fs/bcachefs/btree_locking.h | 2
fs/bcachefs/btree_update_interior.c | 8 +
fs/bcachefs/io_read.c | 4 -
fs/bcachefs/io_write.c | 4 -
fs/bcachefs/journal.c | 5 -
fs/bcachefs/journal_io.c | 9 +
fs/bcachefs/journal_reclaim.c | 9 -
fs/bcachefs/journal_types.h | 11 -
fs/bcachefs/nocow_locking.c | 2
fs/bcachefs/super.c | 12 +-
fs/bcachefs/util.c | 263 ----------------------------------
fs/bcachefs/util.h | 83 -----------
include/linux/time_stats.h | 134 +++++++++++++++++
lib/Kconfig | 4 +
lib/Makefile | 2
lib/time_stats.c | 271 +++++++++++++++++++++++++++++++++++
24 files changed, 470 insertions(+), 406 deletions(-)
create mode 100644 include/linux/time_stats.h
create mode 100644 lib/time_stats.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 98a17270566d3..aa762fe654e3e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22157,6 +22157,13 @@ F: kernel/time/ntp.c
F: kernel/time/time*.c
F: tools/testing/selftests/timers/
+TIME STATS:
+M: Kent Overstreet <kent.overstreet@...ux.dev>
+M: Darrick J. Wong <djwong@...nel.org>
+S: Maintained
+F: include/linux/time_stats.h
+F: lib/time_stats.c
+
TIPC NETWORK LAYER
M: Jon Maloy <jmaloy@...hat.com>
M: Ying Xue <ying.xue@...driver.com>
diff --git a/fs/bcachefs/Kconfig b/fs/bcachefs/Kconfig
index 72d1179262b33..8c587ddd2f85e 100644
--- a/fs/bcachefs/Kconfig
+++ b/fs/bcachefs/Kconfig
@@ -24,7 +24,7 @@ config BCACHEFS_FS
select XXHASH
select SRCU
select SYMBOLIC_ERRNAME
- select MEAN_AND_VARIANCE
+ select TIME_STATS
help
The bcachefs filesystem - a modern, copy on write filesystem, with
support for multiple devices, compression, checksumming, etc.
diff --git a/fs/bcachefs/alloc_foreground.c b/fs/bcachefs/alloc_foreground.c
index 633d3223b353f..ca58193dd9027 100644
--- a/fs/bcachefs/alloc_foreground.c
+++ b/fs/bcachefs/alloc_foreground.c
@@ -236,8 +236,7 @@ static struct open_bucket *__try_alloc_bucket(struct bch_fs *c, struct bch_dev *
if (cl)
closure_wait(&c->open_buckets_wait, cl);
- track_event_change(&c->times[BCH_TIME_blocked_allocate_open_bucket],
- &c->blocked_allocate_open_bucket, true);
+ track_event_change(&c->times[BCH_TIME_blocked_allocate_open_bucket], true);
spin_unlock(&c->freelist_lock);
return ERR_PTR(-BCH_ERR_open_buckets_empty);
}
@@ -263,11 +262,8 @@ static struct open_bucket *__try_alloc_bucket(struct bch_fs *c, struct bch_dev *
ca->nr_open_buckets++;
bch2_open_bucket_hash_add(c, ob);
- track_event_change(&c->times[BCH_TIME_blocked_allocate_open_bucket],
- &c->blocked_allocate_open_bucket, false);
-
- track_event_change(&c->times[BCH_TIME_blocked_allocate],
- &c->blocked_allocate, false);
+ track_event_change(&c->times[BCH_TIME_blocked_allocate_open_bucket], false);
+ track_event_change(&c->times[BCH_TIME_blocked_allocate], false);
spin_unlock(&c->freelist_lock);
return ob;
@@ -555,8 +551,7 @@ static struct open_bucket *bch2_bucket_alloc_trans(struct btree_trans *trans,
goto again;
}
- track_event_change(&c->times[BCH_TIME_blocked_allocate],
- &c->blocked_allocate, true);
+ track_event_change(&c->times[BCH_TIME_blocked_allocate], true);
ob = ERR_PTR(-BCH_ERR_freelist_empty);
goto err;
diff --git a/fs/bcachefs/bcachefs.h b/fs/bcachefs/bcachefs.h
index 69d0d60d50e36..92547d6fd2d95 100644
--- a/fs/bcachefs/bcachefs.h
+++ b/fs/bcachefs/bcachefs.h
@@ -200,6 +200,7 @@
#include <linux/seqlock.h>
#include <linux/shrinker.h>
#include <linux/srcu.h>
+#include <linux/time_stats.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <linux/zstd.h>
@@ -593,7 +594,7 @@ struct bch_dev {
/* The rest of this all shows up in sysfs */
atomic64_t cur_latency[2];
- struct bch2_time_stats io_latency[2];
+ struct time_stats io_latency[2];
#define CONGESTED_MAX 1024
atomic_t congested;
@@ -640,8 +641,8 @@ struct btree_debug {
#define BCH_TRANSACTIONS_NR 128
struct btree_transaction_stats {
- struct bch2_time_stats duration;
- struct bch2_time_stats lock_hold_times;
+ struct time_stats duration;
+ struct time_stats lock_hold_times;
struct mutex lock;
unsigned nr_max_paths;
unsigned journal_entries_size;
@@ -919,8 +920,6 @@ struct bch_fs {
/* ALLOCATOR */
spinlock_t freelist_lock;
struct closure_waitlist freelist_wait;
- u64 blocked_allocate;
- u64 blocked_allocate_open_bucket;
open_bucket_idx_t open_buckets_freelist;
open_bucket_idx_t open_buckets_nr_free;
@@ -1104,7 +1103,7 @@ struct bch_fs {
unsigned copy_gc_enabled:1;
bool promote_whole_extents;
- struct bch2_time_stats times[BCH_TIME_STAT_NR];
+ struct time_stats times[BCH_TIME_STAT_NR];
struct btree_transaction_stats btree_transaction_stats[BCH_TRANSACTIONS_NR];
diff --git a/fs/bcachefs/btree_cache.c b/fs/bcachefs/btree_cache.c
index d7c81beac14af..8b3c04fc406f5 100644
--- a/fs/bcachefs/btree_cache.c
+++ b/fs/bcachefs/btree_cache.c
@@ -648,7 +648,7 @@ struct btree *bch2_btree_node_mem_alloc(struct btree_trans *trans, bool pcpu_rea
bch2_btree_keys_init(b);
set_btree_node_accessed(b);
- bch2_time_stats_update(&c->times[BCH_TIME_btree_node_mem_alloc],
+ time_stats_update(&c->times[BCH_TIME_btree_node_mem_alloc],
start_time);
memalloc_nofs_restore(flags);
diff --git a/fs/bcachefs/btree_gc.c b/fs/bcachefs/btree_gc.c
index 1102995643b13..774df395e4c73 100644
--- a/fs/bcachefs/btree_gc.c
+++ b/fs/bcachefs/btree_gc.c
@@ -1970,7 +1970,7 @@ int bch2_gc_gens(struct bch_fs *c)
c->gc_count++;
- bch2_time_stats_update(&c->times[BCH_TIME_btree_gc], start_time);
+ time_stats_update(&c->times[BCH_TIME_btree_gc], start_time);
trace_and_count(c, gc_gens_end, c);
err:
for_each_member_device(c, ca) {
diff --git a/fs/bcachefs/btree_io.c b/fs/bcachefs/btree_io.c
index aa9b6cbe32269..a56dcabb7ace7 100644
--- a/fs/bcachefs/btree_io.c
+++ b/fs/bcachefs/btree_io.c
@@ -327,7 +327,7 @@ static void btree_node_sort(struct bch_fs *c, struct btree *b,
BUG_ON(vstruct_end(&out->keys) > (void *) out + bytes);
if (sorting_entire_node)
- bch2_time_stats_update(&c->times[BCH_TIME_btree_node_sort],
+ time_stats_update(&c->times[BCH_TIME_btree_node_sort],
start_time);
/* Make sure we preserve bset journal_seq: */
@@ -397,7 +397,7 @@ void bch2_btree_sort_into(struct bch_fs *c,
&dst->format,
true);
- bch2_time_stats_update(&c->times[BCH_TIME_btree_node_sort],
+ time_stats_update(&c->times[BCH_TIME_btree_node_sort],
start_time);
set_btree_bset_end(dst, dst->set);
@@ -1251,7 +1251,7 @@ int bch2_btree_node_read_done(struct bch_fs *c, struct bch_dev *ca,
out:
mempool_free(iter, &c->fill_iter);
printbuf_exit(&buf);
- bch2_time_stats_update(&c->times[BCH_TIME_btree_node_read_done], start_time);
+ time_stats_update(&c->times[BCH_TIME_btree_node_read_done], start_time);
return retry_read;
fsck_err:
if (ret == -BCH_ERR_btree_node_read_err_want_retry ||
@@ -1323,7 +1323,7 @@ static void btree_node_read_work(struct work_struct *work)
}
}
- bch2_time_stats_update(&c->times[BCH_TIME_btree_node_read],
+ time_stats_update(&c->times[BCH_TIME_btree_node_read],
rb->start_time);
bio_put(&rb->bio);
diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index 5467a8635be11..f2d7b1dabcfbb 100644
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -2899,7 +2899,7 @@ u32 bch2_trans_begin(struct btree_trans *trans)
if (!IS_ENABLED(CONFIG_BCACHEFS_NO_LATENCY_ACCT) &&
time_after64(now, trans->last_begin_time + 10))
- __bch2_time_stats_update(&btree_trans_stats(trans)->duration,
+ __time_stats_update(&btree_trans_stats(trans)->duration,
trans->last_begin_time, now);
if (!trans->restarted &&
@@ -3224,7 +3224,7 @@ void bch2_fs_btree_iter_exit(struct bch_fs *c)
s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
s++) {
kfree(s->max_paths_text);
- bch2_time_stats_exit(&s->lock_hold_times);
+ time_stats_exit(&s->lock_hold_times);
}
if (c->btree_trans_barrier_initialized)
@@ -3240,8 +3240,8 @@ void bch2_fs_btree_iter_init_early(struct bch_fs *c)
for (s = c->btree_transaction_stats;
s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
s++) {
- bch2_time_stats_init(&s->duration);
- bch2_time_stats_init(&s->lock_hold_times);
+ time_stats_init(&s->duration);
+ time_stats_init(&s->lock_hold_times);
mutex_init(&s->lock);
}
diff --git a/fs/bcachefs/btree_locking.h b/fs/bcachefs/btree_locking.h
index 4bd72c855da1a..f2e2c5881b7e4 100644
--- a/fs/bcachefs/btree_locking.h
+++ b/fs/bcachefs/btree_locking.h
@@ -122,7 +122,7 @@ static void btree_trans_lock_hold_time_update(struct btree_trans *trans,
struct btree_path *path, unsigned level)
{
#ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
- __bch2_time_stats_update(&btree_trans_stats(trans)->lock_hold_times,
+ __time_stats_update(&btree_trans_stats(trans)->lock_hold_times,
path->l[level].lock_taken_time,
local_clock());
#endif
diff --git a/fs/bcachefs/btree_update_interior.c b/fs/bcachefs/btree_update_interior.c
index 4530b14ff2c37..669379eaea2f0 100644
--- a/fs/bcachefs/btree_update_interior.c
+++ b/fs/bcachefs/btree_update_interior.c
@@ -517,7 +517,7 @@ static void bch2_btree_update_free(struct btree_update *as, struct btree_trans *
bch2_disk_reservation_put(c, &as->disk_res);
bch2_btree_reserve_put(as, trans);
- bch2_time_stats_update(&c->times[BCH_TIME_btree_interior_update_total],
+ time_stats_update(&c->times[BCH_TIME_btree_interior_update_total],
as->start_time);
mutex_lock(&c->btree_interior_update_lock);
@@ -1039,7 +1039,7 @@ static void bch2_btree_update_done(struct btree_update *as, struct btree_trans *
continue_at(&as->cl, btree_update_set_nodes_written,
as->c->btree_interior_update_worker);
- bch2_time_stats_update(&c->times[BCH_TIME_btree_interior_update_foreground],
+ time_stats_update(&c->times[BCH_TIME_btree_interior_update_foreground],
start_time);
}
@@ -1630,7 +1630,7 @@ static int btree_split(struct btree_update *as, struct btree_trans *trans,
bch2_trans_verify_locks(trans);
- bch2_time_stats_update(&c->times[n2
+ time_stats_update(&c->times[n2
? BCH_TIME_btree_node_split
: BCH_TIME_btree_node_compact],
start_time);
@@ -1936,7 +1936,7 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
bch2_btree_update_done(as, trans);
- bch2_time_stats_update(&c->times[BCH_TIME_btree_node_merge], start_time);
+ time_stats_update(&c->times[BCH_TIME_btree_node_merge], start_time);
out:
err:
if (new_path)
diff --git a/fs/bcachefs/io_read.c b/fs/bcachefs/io_read.c
index 3c574d8873a1e..dce136cd22713 100644
--- a/fs/bcachefs/io_read.c
+++ b/fs/bcachefs/io_read.c
@@ -134,7 +134,7 @@ static void promote_done(struct bch_write_op *wop)
container_of(wop, struct promote_op, write.op);
struct bch_fs *c = op->write.op.c;
- bch2_time_stats_update(&c->times[BCH_TIME_data_promote],
+ time_stats_update(&c->times[BCH_TIME_data_promote],
op->start_time);
promote_free(c, op);
}
@@ -356,7 +356,7 @@ static inline struct bch_read_bio *bch2_rbio_free(struct bch_read_bio *rbio)
static void bch2_rbio_done(struct bch_read_bio *rbio)
{
if (rbio->start_time)
- bch2_time_stats_update(&rbio->c->times[BCH_TIME_data_read],
+ time_stats_update(&rbio->c->times[BCH_TIME_data_read],
rbio->start_time);
bio_endio(&rbio->bio);
}
diff --git a/fs/bcachefs/io_write.c b/fs/bcachefs/io_write.c
index 2c098ac017b30..8123a84320e3f 100644
--- a/fs/bcachefs/io_write.c
+++ b/fs/bcachefs/io_write.c
@@ -88,7 +88,7 @@ void bch2_latency_acct(struct bch_dev *ca, u64 submit_time, int rw)
bch2_congested_acct(ca, io_latency, now, rw);
- __bch2_time_stats_update(&ca->io_latency[rw], submit_time, now);
+ __time_stats_update(&ca->io_latency[rw], submit_time, now);
}
#endif
@@ -457,7 +457,7 @@ static void bch2_write_done(struct closure *cl)
EBUG_ON(op->open_buckets.nr);
- bch2_time_stats_update(&c->times[BCH_TIME_data_write], op->start_time);
+ time_stats_update(&c->times[BCH_TIME_data_write], op->start_time);
bch2_disk_reservation_put(c, &op->res);
if (!(op->flags & BCH_WRITE_MOVE))
diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index bc890776eb579..c5d6cc29be870 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -518,8 +518,7 @@ static int __journal_res_get(struct journal *j, struct journal_res *res,
ret = journal_entry_open(j);
if (ret == JOURNAL_ERR_max_in_flight) {
- track_event_change(&c->times[BCH_TIME_blocked_journal_max_in_flight],
- &j->max_in_flight_start, true);
+ track_event_change(&c->times[BCH_TIME_blocked_journal_max_in_flight], true);
if (trace_journal_entry_full_enabled()) {
struct printbuf buf = PRINTBUF;
buf.atomic++;
@@ -727,7 +726,7 @@ int bch2_journal_flush_seq(struct journal *j, u64 seq)
ret = wait_event_interruptible(j->wait, (ret2 = bch2_journal_flush_seq_async(j, seq, NULL)));
if (!ret)
- bch2_time_stats_update(j->flush_seq_time, start_time);
+ time_stats_update(j->flush_seq_time, start_time);
return ret ?: ret2 < 0 ? ret2 : 0;
}
diff --git a/fs/bcachefs/journal_io.c b/fs/bcachefs/journal_io.c
index 47805193f18cc..23401e9686eed 100644
--- a/fs/bcachefs/journal_io.c
+++ b/fs/bcachefs/journal_io.c
@@ -1576,9 +1576,9 @@ static CLOSURE_CALLBACK(journal_write_done)
u64 v, seq;
int err = 0;
- bch2_time_stats_update(!JSET_NO_FLUSH(w->data)
- ? j->flush_write_time
- : j->noflush_write_time, j->write_start_time);
+ time_stats_update(!JSET_NO_FLUSH(w->data)
+ ? j->flush_write_time
+ : j->noflush_write_time, j->write_start_time);
if (!w->devs_written.nr) {
bch_err(c, "unable to write journal to sufficient devices");
@@ -1639,8 +1639,7 @@ static CLOSURE_CALLBACK(journal_write_done)
bch2_journal_reclaim_fast(j);
bch2_journal_space_available(j);
- track_event_change(&c->times[BCH_TIME_blocked_journal_max_in_flight],
- &j->max_in_flight_start, false);
+ track_event_change(&c->times[BCH_TIME_blocked_journal_max_in_flight], false);
closure_wake_up(&w->wait);
journal_wake(j);
diff --git a/fs/bcachefs/journal_reclaim.c b/fs/bcachefs/journal_reclaim.c
index 2cf626315652c..d58503b73b966 100644
--- a/fs/bcachefs/journal_reclaim.c
+++ b/fs/bcachefs/journal_reclaim.c
@@ -62,12 +62,9 @@ void bch2_journal_set_watermark(struct journal *j)
? BCH_WATERMARK_reclaim
: BCH_WATERMARK_stripe;
- if (track_event_change(&c->times[BCH_TIME_blocked_journal_low_on_space],
- &j->low_on_space_start, low_on_space) ||
- track_event_change(&c->times[BCH_TIME_blocked_journal_low_on_pin],
- &j->low_on_pin_start, low_on_pin) ||
- track_event_change(&c->times[BCH_TIME_blocked_write_buffer_full],
- &j->write_buffer_full_start, low_on_wb))
+ if (track_event_change(&c->times[BCH_TIME_blocked_journal_low_on_space], low_on_space) ||
+ track_event_change(&c->times[BCH_TIME_blocked_journal_low_on_pin], low_on_pin) ||
+ track_event_change(&c->times[BCH_TIME_blocked_write_buffer_full], low_on_wb))
trace_and_count(c, journal_full, c);
swap(watermark, j->watermark);
diff --git a/fs/bcachefs/journal_types.h b/fs/bcachefs/journal_types.h
index 38817c7a08515..b93e02c0a178a 100644
--- a/fs/bcachefs/journal_types.h
+++ b/fs/bcachefs/journal_types.h
@@ -274,14 +274,9 @@ struct journal {
u64 nr_noflush_writes;
u64 entry_bytes_written;
- u64 low_on_space_start;
- u64 low_on_pin_start;
- u64 max_in_flight_start;
- u64 write_buffer_full_start;
-
- struct bch2_time_stats *flush_write_time;
- struct bch2_time_stats *noflush_write_time;
- struct bch2_time_stats *flush_seq_time;
+ struct time_stats *flush_write_time;
+ struct time_stats *noflush_write_time;
+ struct time_stats *flush_seq_time;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map res_map;
diff --git a/fs/bcachefs/nocow_locking.c b/fs/bcachefs/nocow_locking.c
index 3c21981a4a1c0..181efa4a83fa1 100644
--- a/fs/bcachefs/nocow_locking.c
+++ b/fs/bcachefs/nocow_locking.c
@@ -85,7 +85,7 @@ void __bch2_bucket_nocow_lock(struct bucket_nocow_lock_table *t,
u64 start_time = local_clock();
__closure_wait_event(&l->wait, __bch2_bucket_nocow_trylock(l, dev_bucket, flags));
- bch2_time_stats_update(&c->times[BCH_TIME_nocow_lock_contended], start_time);
+ time_stats_update(&c->times[BCH_TIME_nocow_lock_contended], start_time);
}
}
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index b9e2c1032b920..c491c5e102287 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -520,7 +520,7 @@ static void __bch2_fs_free(struct bch_fs *c)
unsigned i;
for (i = 0; i < BCH_TIME_STAT_NR; i++)
- bch2_time_stats_exit(&c->times[i]);
+ time_stats_exit(&c->times[i]);
bch2_free_pending_node_rewrites(c);
bch2_fs_sb_errors_exit(c);
@@ -753,7 +753,7 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
c->journal_keys.initial_ref_held = true;
for (i = 0; i < BCH_TIME_STAT_NR; i++)
- bch2_time_stats_init(&c->times[i]);
+ time_stats_init(&c->times[i]);
bch2_fs_copygc_init(c);
bch2_fs_btree_key_cache_init_early(&c->btree_key_cache);
@@ -1168,8 +1168,8 @@ static void bch2_dev_free(struct bch_dev *ca)
bch2_dev_buckets_free(ca);
free_page((unsigned long) ca->sb_read_scratch);
- bch2_time_stats_exit(&ca->io_latency[WRITE]);
- bch2_time_stats_exit(&ca->io_latency[READ]);
+ time_stats_exit(&ca->io_latency[WRITE]);
+ time_stats_exit(&ca->io_latency[READ]);
percpu_ref_exit(&ca->io_ref);
percpu_ref_exit(&ca->ref);
@@ -1260,8 +1260,8 @@ static struct bch_dev *__bch2_dev_alloc(struct bch_fs *c,
INIT_WORK(&ca->io_error_work, bch2_io_error_work);
- bch2_time_stats_init(&ca->io_latency[READ]);
- bch2_time_stats_init(&ca->io_latency[WRITE]);
+ time_stats_init(&ca->io_latency[READ]);
+ time_stats_init(&ca->io_latency[WRITE]);
ca->io_latency[READ].quantiles_enabled = true;
ca->io_latency[WRITE].quantiles_enabled = true;
diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c
index 4c63f81e18bc4..88853513a15fa 100644
--- a/fs/bcachefs/util.c
+++ b/fs/bcachefs/util.c
@@ -337,32 +337,6 @@ void bch2_prt_datetime(struct printbuf *out, time64_t sec)
}
#endif
-static const struct time_unit {
- const char *name;
- u64 nsecs;
-} time_units[] = {
- { "ns", 1 },
- { "us", NSEC_PER_USEC },
- { "ms", NSEC_PER_MSEC },
- { "s", NSEC_PER_SEC },
- { "m", (u64) NSEC_PER_SEC * 60},
- { "h", (u64) NSEC_PER_SEC * 3600},
- { "eon", U64_MAX },
-};
-
-static const struct time_unit *pick_time_units(u64 ns)
-{
- const struct time_unit *u;
-
- for (u = time_units;
- u + 1 < time_units + ARRAY_SIZE(time_units) &&
- ns >= u[1].nsecs << 1;
- u++)
- ;
-
- return u;
-}
-
void bch2_pr_time_units(struct printbuf *out, u64 ns)
{
const struct time_unit *u = pick_time_units(ns);
@@ -370,121 +344,6 @@ void bch2_pr_time_units(struct printbuf *out, u64 ns)
prt_printf(out, "%llu %s", div_u64(ns, u->nsecs), u->name);
}
-/* time stats: */
-
-#ifndef CONFIG_BCACHEFS_NO_LATENCY_ACCT
-static void bch2_quantiles_update(struct bch2_quantiles *q, u64 v)
-{
- unsigned i = 0;
-
- while (i < ARRAY_SIZE(q->entries)) {
- struct bch2_quantile_entry *e = q->entries + i;
-
- if (unlikely(!e->step)) {
- e->m = v;
- e->step = max_t(unsigned, v / 2, 1024);
- } else if (e->m > v) {
- e->m = e->m >= e->step
- ? e->m - e->step
- : 0;
- } else if (e->m < v) {
- e->m = e->m + e->step > e->m
- ? e->m + e->step
- : U32_MAX;
- }
-
- if ((e->m > v ? e->m - v : v - e->m) < e->step)
- e->step = max_t(unsigned, e->step / 2, 1);
-
- if (v >= e->m)
- break;
-
- i = eytzinger0_child(i, v > e->m);
- }
-}
-
-static inline void bch2_time_stats_update_one(struct bch2_time_stats *stats,
- u64 start, u64 end)
-{
- u64 duration, freq;
-
- if (time_after64(end, start)) {
- duration = end - start;
- mean_and_variance_update(&stats->duration_stats, duration);
- mean_and_variance_weighted_update(&stats->duration_stats_weighted, duration);
- stats->max_duration = max(stats->max_duration, duration);
- stats->min_duration = min(stats->min_duration, duration);
- stats->total_duration += duration;
- bch2_quantiles_update(&stats->quantiles, duration);
- }
-
- if (stats->last_event && time_after64(end, stats->last_event)) {
- freq = end - stats->last_event;
- mean_and_variance_update(&stats->freq_stats, freq);
- mean_and_variance_weighted_update(&stats->freq_stats_weighted, freq);
- stats->max_freq = max(stats->max_freq, freq);
- stats->min_freq = min(stats->min_freq, freq);
- }
-
- stats->last_event = end;
-}
-
-static void __bch2_time_stats_clear_buffer(struct bch2_time_stats *stats,
- struct bch2_time_stat_buffer *b)
-{
- for (struct bch2_time_stat_buffer_entry *i = b->entries;
- i < b->entries + ARRAY_SIZE(b->entries);
- i++)
- bch2_time_stats_update_one(stats, i->start, i->end);
- b->nr = 0;
-}
-
-static noinline void bch2_time_stats_clear_buffer(struct bch2_time_stats *stats,
- struct bch2_time_stat_buffer *b)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&stats->lock, flags);
- __bch2_time_stats_clear_buffer(stats, b);
- spin_unlock_irqrestore(&stats->lock, flags);
-}
-
-void __bch2_time_stats_update(struct bch2_time_stats *stats, u64 start, u64 end)
-{
- unsigned long flags;
-
- WARN_ONCE(!stats->duration_stats_weighted.weight ||
- !stats->freq_stats_weighted.weight,
- "uninitialized time_stats");
-
- if (!stats->buffer) {
- spin_lock_irqsave(&stats->lock, flags);
- bch2_time_stats_update_one(stats, start, end);
-
- if (mean_and_variance_weighted_get_mean(stats->freq_stats_weighted) < 32 &&
- stats->duration_stats.n > 1024)
- stats->buffer =
- alloc_percpu_gfp(struct bch2_time_stat_buffer,
- GFP_ATOMIC);
- spin_unlock_irqrestore(&stats->lock, flags);
- } else {
- struct bch2_time_stat_buffer *b;
-
- preempt_disable();
- b = this_cpu_ptr(stats->buffer);
-
- BUG_ON(b->nr >= ARRAY_SIZE(b->entries));
- b->entries[b->nr++] = (struct bch2_time_stat_buffer_entry) {
- .start = start,
- .end = end
- };
-
- if (unlikely(b->nr == ARRAY_SIZE(b->entries)))
- bch2_time_stats_clear_buffer(stats, b);
- preempt_enable();
- }
-}
-
static void bch2_pr_time_units_aligned(struct printbuf *out, u64 ns)
{
const struct time_unit *u = pick_time_units(ns);
@@ -504,7 +363,7 @@ static inline void pr_name_and_units(struct printbuf *out, const char *name, u64
#define TABSTOP_SIZE 12
-void bch2_time_stats_to_text(struct printbuf *out, struct bch2_time_stats *stats)
+void bch2_time_stats_to_text(struct printbuf *out, struct time_stats *stats)
{
s64 f_mean = 0, d_mean = 0;
u64 f_stddev = 0, d_stddev = 0;
@@ -514,7 +373,7 @@ void bch2_time_stats_to_text(struct printbuf *out, struct bch2_time_stats *stats
spin_lock_irq(&stats->lock);
for_each_possible_cpu(cpu)
- __bch2_time_stats_clear_buffer(stats, per_cpu_ptr(stats->buffer, cpu));
+ __time_stats_clear_buffer(stats, per_cpu_ptr(stats->buffer, cpu));
spin_unlock_irq(&stats->lock);
}
@@ -625,124 +484,6 @@ void bch2_time_stats_to_text(struct printbuf *out, struct bch2_time_stats *stats
}
}
-#include <linux/seq_buf.h>
-
-static void seq_buf_time_units_aligned(struct seq_buf *out, u64 ns)
-{
- const struct time_unit *u = pick_time_units(ns);
-
- seq_buf_printf(out, "%8llu %s", div64_u64(ns, u->nsecs), u->name);
-}
-
-void bch2_time_stats_to_seq_buf(struct seq_buf *out, struct bch2_time_stats *stats)
-{
- s64 f_mean = 0, d_mean = 0;
- u64 f_stddev = 0, d_stddev = 0;
-
- if (stats->buffer) {
- int cpu;
-
- spin_lock_irq(&stats->lock);
- for_each_possible_cpu(cpu)
- __bch2_time_stats_clear_buffer(stats, per_cpu_ptr(stats->buffer, cpu));
- spin_unlock_irq(&stats->lock);
- }
-
- /*
- * avoid divide by zero
- */
- if (stats->freq_stats.n) {
- f_mean = mean_and_variance_get_mean(stats->freq_stats);
- f_stddev = mean_and_variance_get_stddev(stats->freq_stats);
- d_mean = mean_and_variance_get_mean(stats->duration_stats);
- d_stddev = mean_and_variance_get_stddev(stats->duration_stats);
- }
-
- seq_buf_printf(out, "count: %llu\n", stats->duration_stats.n);
-
- seq_buf_printf(out, " since mount recent\n");
-
- seq_buf_printf(out, "duration of events\n");
-
- seq_buf_printf(out, " min: ");
- seq_buf_time_units_aligned(out, stats->min_duration);
- seq_buf_printf(out, "\n");
-
- seq_buf_printf(out, " max: ");
- seq_buf_time_units_aligned(out, stats->max_duration);
- seq_buf_printf(out, "\n");
-
- seq_buf_printf(out, " total: ");
- seq_buf_time_units_aligned(out, stats->total_duration);
- seq_buf_printf(out, "\n");
-
- seq_buf_printf(out, " mean: ");
- seq_buf_time_units_aligned(out, d_mean);
- seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_mean(stats->duration_stats_weighted));
- seq_buf_printf(out, "\n");
-
- seq_buf_printf(out, " stddev: ");
- seq_buf_time_units_aligned(out, d_stddev);
- seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_stddev(stats->duration_stats_weighted));
- seq_buf_printf(out, "\n");
-
- seq_buf_printf(out, "time between events\n");
-
- seq_buf_printf(out, " min: ");
- seq_buf_time_units_aligned(out, stats->min_freq);
- seq_buf_printf(out, "\n");
-
- seq_buf_printf(out, " max: ");
- seq_buf_time_units_aligned(out, stats->max_freq);
- seq_buf_printf(out, "\n");
-
- seq_buf_printf(out, " mean: ");
- seq_buf_time_units_aligned(out, f_mean);
- seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_mean(stats->freq_stats_weighted));
- seq_buf_printf(out, "\n");
-
- seq_buf_printf(out, " stddev: ");
- seq_buf_time_units_aligned(out, f_stddev);
- seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_stddev(stats->freq_stats_weighted));
- seq_buf_printf(out, "\n");
-
- if (stats->quantiles_enabled) {
- int i = eytzinger0_first(NR_QUANTILES);
- const struct time_unit *u =
- pick_time_units(stats->quantiles.entries[i].m);
- u64 last_q = 0;
-
- prt_printf(out, "quantiles (%s):\t", u->name);
- eytzinger0_for_each(i, NR_QUANTILES) {
- bool is_last = eytzinger0_next(i, NR_QUANTILES) == -1;
-
- u64 q = max(stats->quantiles.entries[i].m, last_q);
- seq_buf_printf(out, "%llu ", div_u64(q, u->nsecs));
- if (is_last)
- seq_buf_printf(out, "\n");
- last_q = q;
- }
- }
-}
-#else
-void bch2_time_stats_to_text(struct printbuf *out, struct bch2_time_stats *stats) {}
-#endif
-
-void bch2_time_stats_exit(struct bch2_time_stats *stats)
-{
- free_percpu(stats->buffer);
-}
-
-void bch2_time_stats_init(struct bch2_time_stats *stats)
-{
- memset(stats, 0, sizeof(*stats));
- stats->duration_stats_weighted.weight = 8;
- stats->freq_stats_weighted.weight = 8;
- stats->min_duration = U64_MAX;
- stats->min_freq = U64_MAX;
- spin_lock_init(&stats->lock);
-}
-
/* ratelimit: */
/**
diff --git a/fs/bcachefs/util.h b/fs/bcachefs/util.h
index 7ff2d4fe26f68..cf8d16a911622 100644
--- a/fs/bcachefs/util.h
+++ b/fs/bcachefs/util.h
@@ -15,6 +15,7 @@
#include <linux/preempt.h>
#include <linux/ratelimit.h>
#include <linux/slab.h>
+#include <linux/time_stats.h>
#include <linux/vmalloc.h>
#include <linux/workqueue.h>
#include <linux/mean_and_variance.h>
@@ -360,87 +361,7 @@ static inline void prt_bdevname(struct printbuf *out, struct block_device *bdev)
#endif
}
-#define NR_QUANTILES 15
-#define QUANTILE_IDX(i) inorder_to_eytzinger0(i, NR_QUANTILES)
-#define QUANTILE_FIRST eytzinger0_first(NR_QUANTILES)
-#define QUANTILE_LAST eytzinger0_last(NR_QUANTILES)
-
-struct bch2_quantiles {
- struct bch2_quantile_entry {
- u64 m;
- u64 step;
- } entries[NR_QUANTILES];
-};
-
-struct bch2_time_stat_buffer {
- unsigned nr;
- struct bch2_time_stat_buffer_entry {
- u64 start;
- u64 end;
- } entries[32];
-};
-
-struct bch2_time_stats {
- spinlock_t lock;
- bool quantiles_enabled;
- /* all fields are in nanoseconds */
- u64 min_duration;
- u64 max_duration;
- u64 total_duration;
- u64 max_freq;
- u64 min_freq;
- u64 last_event;
- struct bch2_quantiles quantiles;
-
- struct mean_and_variance duration_stats;
- struct mean_and_variance_weighted duration_stats_weighted;
- struct mean_and_variance freq_stats;
- struct mean_and_variance_weighted freq_stats_weighted;
- struct bch2_time_stat_buffer __percpu *buffer;
-};
-
-#ifndef CONFIG_BCACHEFS_NO_LATENCY_ACCT
-void __bch2_time_stats_update(struct bch2_time_stats *stats, u64, u64);
-
-static inline void bch2_time_stats_update(struct bch2_time_stats *stats, u64 start)
-{
- __bch2_time_stats_update(stats, start, local_clock());
-}
-
-static inline bool track_event_change(struct bch2_time_stats *stats,
- u64 *start, bool v)
-{
- if (v != !!*start) {
- if (!v) {
- bch2_time_stats_update(stats, *start);
- *start = 0;
- } else {
- *start = local_clock() ?: 1;
- return true;
- }
- }
-
- return false;
-}
-#else
-static inline void __bch2_time_stats_update(struct bch2_time_stats *stats, u64 start, u64 end) {}
-static inline void bch2_time_stats_update(struct bch2_time_stats *stats, u64 start) {}
-static inline bool track_event_change(struct bch2_time_stats *stats,
- u64 *start, bool v)
-{
- bool ret = v && !*start;
- *start = v;
- return ret;
-}
-#endif
-
-void bch2_time_stats_to_text(struct printbuf *, struct bch2_time_stats *);
-
-struct seq_buf;
-void bch2_time_stats_to_seq_buf(struct seq_buf *, struct bch2_time_stats *);
-
-void bch2_time_stats_exit(struct bch2_time_stats *);
-void bch2_time_stats_init(struct bch2_time_stats *);
+void bch2_time_stats_to_text(struct printbuf *, struct time_stats *);
#define ewma_add(ewma, val, weight) \
({ \
diff --git a/include/linux/time_stats.h b/include/linux/time_stats.h
new file mode 100644
index 0000000000000..caefa7aba65a0
--- /dev/null
+++ b/include/linux/time_stats.h
@@ -0,0 +1,134 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * time_stats - collect statistics on events that have a duration, with nicely
+ * formatted textual output on demand
+ *
+ * - percpu buffering of event collection: cheap enough to shotgun
+ * everywhere without worrying about overhead
+ *
+ * tracks:
+ * - number of events
+ * - maximum event duration ever seen
+ * - sum of all event durations
+ * - average event duration, standard and weighted
+ * - standard deviation of event durations, standard and weighted
+ * and analagous statistics for the frequency of events
+ *
+ * We provide both mean and weighted mean (exponentially weighted), and standard
+ * deviation and weighted standard deviation, to give an efficient-to-compute
+ * view of current behaviour versus. average behaviour - "did this event source
+ * just become wonky, or is this typical?".
+ *
+ * Particularly useful for tracking down latency issues.
+ */
+#ifndef _LINUX_TIME_STATS_H
+#define _LINUX_TIME_STATS_H
+
+#include <linux/mean_and_variance.h>
+#include <linux/sched/clock.h>
+#include <linux/spinlock_types.h>
+
+struct time_unit {
+ const char *name;
+ u64 nsecs;
+};
+
+/*
+ * given a nanosecond value, pick the preferred time units for printing:
+ */
+const struct time_unit *pick_time_units(u64 ns);
+
+/*
+ * quantiles - do not use:
+ *
+ * Only enabled if time_stats->quantiles_enabled has been manually set - don't
+ * use in new code.
+ */
+
+#define NR_QUANTILES 15
+#define QUANTILE_IDX(i) inorder_to_eytzinger0(i, NR_QUANTILES)
+#define QUANTILE_FIRST eytzinger0_first(NR_QUANTILES)
+#define QUANTILE_LAST eytzinger0_last(NR_QUANTILES)
+
+struct quantiles {
+ struct quantile_entry {
+ u64 m;
+ u64 step;
+ } entries[NR_QUANTILES];
+};
+
+struct time_stat_buffer {
+ unsigned nr;
+ struct time_stat_buffer_entry {
+ u64 start;
+ u64 end;
+ } entries[32];
+};
+
+struct time_stats {
+ spinlock_t lock;
+ bool quantiles_enabled;
+ /* all fields are in nanoseconds */
+ u64 min_duration;
+ u64 max_duration;
+ u64 total_duration;
+ u64 max_freq;
+ u64 min_freq;
+ u64 last_event;
+ u64 last_event_start;
+ struct quantiles quantiles;
+
+ struct mean_and_variance duration_stats;
+ struct mean_and_variance_weighted duration_stats_weighted;
+ struct mean_and_variance freq_stats;
+ struct mean_and_variance_weighted freq_stats_weighted;
+ struct time_stat_buffer __percpu *buffer;
+};
+
+void __time_stats_clear_buffer(struct time_stats *, struct time_stat_buffer *);
+void __time_stats_update(struct time_stats *stats, u64, u64);
+
+/**
+ * time_stats_update - collect a new event being tracked
+ *
+ * @stats - time_stats to update
+ * @start - start time of event, recorded with local_clock()
+ *
+ * The end duration of the event will be the current time
+ */
+static inline void time_stats_update(struct time_stats *stats, u64 start)
+{
+ __time_stats_update(stats, start, local_clock());
+}
+
+/**
+ * track_event_change - track state change events
+ *
+ * @stats - time_stats to update
+ * @v - new state, true or false
+ *
+ * Use this when tracking time stats for state changes, i.e. resource X becoming
+ * blocked/unblocked.
+ */
+static inline bool track_event_change(struct time_stats *stats, bool v)
+{
+ if (v != !!stats->last_event_start) {
+ if (!v) {
+ time_stats_update(stats, stats->last_event_start);
+ stats->last_event_start = 0;
+ } else {
+ stats->last_event_start = local_clock() ?: 1;
+ return true;
+ }
+ }
+
+ return false;
+}
+
+struct seq_buf;
+void time_stats_to_seq_buf(struct seq_buf *, struct time_stats *);
+
+void time_stats_exit(struct time_stats *);
+void time_stats_init(struct time_stats *);
+
+#endif /* _LINUX_TIME_STATS_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index 5ddda7c2ed9b3..3ba8b965f8c7e 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -785,3 +785,7 @@ config POLYNOMIAL
config FIRMWARE_TABLE
bool
+
+config TIME_STATS
+ tristate
+ select MEAN_AND_VARIANCE
diff --git a/lib/Makefile b/lib/Makefile
index 6b09731d8e619..57858997c87aa 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -370,6 +370,8 @@ obj-$(CONFIG_SBITMAP) += sbitmap.o
obj-$(CONFIG_PARMAN) += parman.o
+obj-$(CONFIG_TIME_STATS) += time_stats.o
+
obj-y += group_cpus.o
# GCC library routines
diff --git a/lib/time_stats.c b/lib/time_stats.c
new file mode 100644
index 0000000000000..081aeba88b535
--- /dev/null
+++ b/lib/time_stats.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/eytzinger.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/preempt.h>
+#include <linux/time.h>
+#include <linux/time_stats.h>
+#include <linux/spinlock.h>
+
+static const struct time_unit time_units[] = {
+ { "ns", 1 },
+ { "us", NSEC_PER_USEC },
+ { "ms", NSEC_PER_MSEC },
+ { "s", NSEC_PER_SEC },
+ { "m", (u64) NSEC_PER_SEC * 60},
+ { "h", (u64) NSEC_PER_SEC * 3600},
+ { "eon", U64_MAX },
+};
+
+const struct time_unit *pick_time_units(u64 ns)
+{
+ const struct time_unit *u;
+
+ for (u = time_units;
+ u + 1 < time_units + ARRAY_SIZE(time_units) &&
+ ns >= u[1].nsecs << 1;
+ u++)
+ ;
+
+ return u;
+}
+EXPORT_SYMBOL_GPL(pick_time_units);
+
+static void quantiles_update(struct quantiles *q, u64 v)
+{
+ unsigned i = 0;
+
+ while (i < ARRAY_SIZE(q->entries)) {
+ struct quantile_entry *e = q->entries + i;
+
+ if (unlikely(!e->step)) {
+ e->m = v;
+ e->step = max_t(unsigned, v / 2, 1024);
+ } else if (e->m > v) {
+ e->m = e->m >= e->step
+ ? e->m - e->step
+ : 0;
+ } else if (e->m < v) {
+ e->m = e->m + e->step > e->m
+ ? e->m + e->step
+ : U32_MAX;
+ }
+
+ if ((e->m > v ? e->m - v : v - e->m) < e->step)
+ e->step = max_t(unsigned, e->step / 2, 1);
+
+ if (v >= e->m)
+ break;
+
+ i = eytzinger0_child(i, v > e->m);
+ }
+}
+
+static inline void time_stats_update_one(struct time_stats *stats,
+ u64 start, u64 end)
+{
+ u64 duration, freq;
+
+ if (time_after64(end, start)) {
+ duration = end - start;
+ mean_and_variance_update(&stats->duration_stats, duration);
+ mean_and_variance_weighted_update(&stats->duration_stats_weighted, duration);
+ stats->max_duration = max(stats->max_duration, duration);
+ stats->min_duration = min(stats->min_duration, duration);
+ stats->total_duration += duration;
+
+ if (stats->quantiles_enabled)
+ quantiles_update(&stats->quantiles, duration);
+ }
+
+ if (stats->last_event && time_after64(end, stats->last_event)) {
+ freq = end - stats->last_event;
+ mean_and_variance_update(&stats->freq_stats, freq);
+ mean_and_variance_weighted_update(&stats->freq_stats_weighted, freq);
+ stats->max_freq = max(stats->max_freq, freq);
+ stats->min_freq = min(stats->min_freq, freq);
+ }
+
+ stats->last_event = end;
+}
+
+void __time_stats_clear_buffer(struct time_stats *stats,
+ struct time_stat_buffer *b)
+{
+ for (struct time_stat_buffer_entry *i = b->entries;
+ i < b->entries + ARRAY_SIZE(b->entries);
+ i++)
+ time_stats_update_one(stats, i->start, i->end);
+ b->nr = 0;
+}
+EXPORT_SYMBOL_GPL(__time_stats_clear_buffer);
+
+static noinline void time_stats_clear_buffer(struct time_stats *stats,
+ struct time_stat_buffer *b)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&stats->lock, flags);
+ __time_stats_clear_buffer(stats, b);
+ spin_unlock_irqrestore(&stats->lock, flags);
+}
+
+void __time_stats_update(struct time_stats *stats, u64 start, u64 end)
+{
+ unsigned long flags;
+
+ WARN_ONCE(!stats->duration_stats_weighted.weight ||
+ !stats->freq_stats_weighted.weight,
+ "uninitialized time_stats");
+
+ if (!stats->buffer) {
+ spin_lock_irqsave(&stats->lock, flags);
+ time_stats_update_one(stats, start, end);
+
+ if (mean_and_variance_weighted_get_mean(stats->freq_stats_weighted) < 32 &&
+ stats->duration_stats.n > 1024)
+ stats->buffer =
+ alloc_percpu_gfp(struct time_stat_buffer,
+ GFP_ATOMIC);
+ spin_unlock_irqrestore(&stats->lock, flags);
+ } else {
+ struct time_stat_buffer *b;
+
+ preempt_disable();
+ b = this_cpu_ptr(stats->buffer);
+
+ BUG_ON(b->nr >= ARRAY_SIZE(b->entries));
+ b->entries[b->nr++] = (struct time_stat_buffer_entry) {
+ .start = start,
+ .end = end
+ };
+
+ if (unlikely(b->nr == ARRAY_SIZE(b->entries)))
+ time_stats_clear_buffer(stats, b);
+ preempt_enable();
+ }
+}
+EXPORT_SYMBOL_GPL(__time_stats_update);
+
+#include <linux/seq_buf.h>
+
+static void seq_buf_time_units_aligned(struct seq_buf *out, u64 ns)
+{
+ const struct time_unit *u = pick_time_units(ns);
+
+ seq_buf_printf(out, "%8llu %s", div64_u64(ns, u->nsecs), u->name);
+}
+
+void time_stats_to_seq_buf(struct seq_buf *out, struct time_stats *stats)
+{
+ s64 f_mean = 0, d_mean = 0;
+ u64 f_stddev = 0, d_stddev = 0;
+
+ if (stats->buffer) {
+ int cpu;
+
+ spin_lock_irq(&stats->lock);
+ for_each_possible_cpu(cpu)
+ __time_stats_clear_buffer(stats, per_cpu_ptr(stats->buffer, cpu));
+ spin_unlock_irq(&stats->lock);
+ }
+
+ /*
+ * avoid divide by zero
+ */
+ if (stats->freq_stats.n) {
+ f_mean = mean_and_variance_get_mean(stats->freq_stats);
+ f_stddev = mean_and_variance_get_stddev(stats->freq_stats);
+ d_mean = mean_and_variance_get_mean(stats->duration_stats);
+ d_stddev = mean_and_variance_get_stddev(stats->duration_stats);
+ }
+
+ seq_buf_printf(out, "count: %llu\n", stats->duration_stats.n);
+
+ seq_buf_printf(out, " since mount recent\n");
+
+ seq_buf_printf(out, "duration of events\n");
+
+ seq_buf_printf(out, " min: ");
+ seq_buf_time_units_aligned(out, stats->min_duration);
+ seq_buf_printf(out, "\n");
+
+ seq_buf_printf(out, " max: ");
+ seq_buf_time_units_aligned(out, stats->max_duration);
+ seq_buf_printf(out, "\n");
+
+ seq_buf_printf(out, " total: ");
+ seq_buf_time_units_aligned(out, stats->total_duration);
+ seq_buf_printf(out, "\n");
+
+ seq_buf_printf(out, " mean: ");
+ seq_buf_time_units_aligned(out, d_mean);
+ seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_mean(stats->duration_stats_weighted));
+ seq_buf_printf(out, "\n");
+
+ seq_buf_printf(out, " stddev: ");
+ seq_buf_time_units_aligned(out, d_stddev);
+ seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_stddev(stats->duration_stats_weighted));
+ seq_buf_printf(out, "\n");
+
+ seq_buf_printf(out, "time between events\n");
+
+ seq_buf_printf(out, " min: ");
+ seq_buf_time_units_aligned(out, stats->min_freq);
+ seq_buf_printf(out, "\n");
+
+ seq_buf_printf(out, " max: ");
+ seq_buf_time_units_aligned(out, stats->max_freq);
+ seq_buf_printf(out, "\n");
+
+ seq_buf_printf(out, " mean: ");
+ seq_buf_time_units_aligned(out, f_mean);
+ seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_mean(stats->freq_stats_weighted));
+ seq_buf_printf(out, "\n");
+
+ seq_buf_printf(out, " stddev: ");
+ seq_buf_time_units_aligned(out, f_stddev);
+ seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_stddev(stats->freq_stats_weighted));
+ seq_buf_printf(out, "\n");
+
+ if (stats->quantiles_enabled) {
+ int i = eytzinger0_first(NR_QUANTILES);
+ const struct time_unit *u =
+ pick_time_units(stats->quantiles.entries[i].m);
+ u64 last_q = 0;
+
+ seq_buf_printf(out, "quantiles (%s):\t", u->name);
+ eytzinger0_for_each(i, NR_QUANTILES) {
+ bool is_last = eytzinger0_next(i, NR_QUANTILES) == -1;
+
+ u64 q = max(stats->quantiles.entries[i].m, last_q);
+ seq_buf_printf(out, "%llu ", div_u64(q, u->nsecs));
+ if (is_last)
+ seq_buf_printf(out, "\n");
+ last_q = q;
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(time_stats_to_seq_buf);
+
+void time_stats_exit(struct time_stats *stats)
+{
+ free_percpu(stats->buffer);
+}
+EXPORT_SYMBOL_GPL(time_stats_exit);
+
+void time_stats_init(struct time_stats *stats)
+{
+ memset(stats, 0, sizeof(*stats));
+ stats->duration_stats_weighted.weight = 8;
+ stats->freq_stats_weighted.weight = 8;
+ stats->min_duration = U64_MAX;
+ stats->min_freq = U64_MAX;
+ spin_lock_init(&stats->lock);
+}
+EXPORT_SYMBOL_GPL(time_stats_init);
+
+MODULE_AUTHOR("Kent Overstreet");
+MODULE_LICENSE("GPL");
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