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Fix/improve dbuf hits accounting 

Instead of clearing stats inside arc_buf_alloc_impl() do it inside
arc_hdr_alloc() and arc_release().  It fixes statistics being wiped
every time a new dbuf is filled from the ARC.

Remove b_l1hdr.b_l2_hits. L2ARC hits are accounted at b_l2hdr.b_hits.
Since the hits are accounted under hash lock, replace atomics with
simple increments.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <george.wilson@delphix.com>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored-By: iXsystems, Inc.
Closes #12422
This commit is contained in:
Alexander Motin 2021-08-17 11:50:31 -04:00 committed by GitHub
parent 7f9d9e6f39
commit cfe8e960f1
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 16 additions and 28 deletions
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4
include/os/linux/zfs/sys/trace_arc.h
View File

@ -80,7 +80,7 @@ DECLARE_EVENT_CLASS(zfs_arc_buf_hdr_class,
__entry->hdr_mru_ghost_hits = ab->b_l1hdr.b_mru_ghost_hits;
__entry->hdr_mfu_hits = ab->b_l1hdr.b_mfu_hits;
__entry->hdr_mfu_ghost_hits = ab->b_l1hdr.b_mfu_ghost_hits;
__entry->hdr_l2_hits = ab->b_l1hdr.b_l2_hits;
__entry->hdr_l2_hits = ab->b_l2hdr.b_hits;
__entry->hdr_refcount = ab->b_l1hdr.b_refcnt.rc_count;
),
TP_printk("hdr { dva 0x%llx:0x%llx birth %llu "
@ -238,7 +238,7 @@ DECLARE_EVENT_CLASS(zfs_arc_miss_class,
__entry->hdr_mru_ghost_hits = hdr->b_l1hdr.b_mru_ghost_hits;
__entry->hdr_mfu_hits = hdr->b_l1hdr.b_mfu_hits;
__entry->hdr_mfu_ghost_hits = hdr->b_l1hdr.b_mfu_ghost_hits;
__entry->hdr_l2_hits = hdr->b_l1hdr.b_l2_hits;
__entry->hdr_l2_hits = hdr->b_l2hdr.b_hits;
__entry->hdr_refcount = hdr->b_l1hdr.b_refcnt.rc_count;
__entry->bp_dva0[0] = bp->blk_dva[0].dva_word[0];

10
include/sys/arc_impl.h
View File

@ -153,24 +153,22 @@ typedef struct l1arc_buf_hdr {
kmutex_t b_freeze_lock;
zio_cksum_t *b_freeze_cksum;
arc_buf_t *b_buf;
uint32_t b_bufcnt;
/* for waiting on writes to complete */
/* for waiting on reads to complete */
kcondvar_t b_cv;
uint8_t b_byteswap;
/* protected by arc state mutex */
arc_state_t *b_state;
multilist_node_t b_arc_node;
/* updated atomically */
/* protected by hash lock */
clock_t b_arc_access;
uint32_t b_mru_hits;
uint32_t b_mru_ghost_hits;
uint32_t b_mfu_hits;
uint32_t b_mfu_ghost_hits;
uint32_t b_l2_hits;
uint32_t b_bufcnt;
arc_buf_t *b_buf;
/* self protecting */
zfs_refcount_t b_refcnt;

30
module/zfs/arc.c
View File

@ -2740,12 +2740,6 @@ arc_buf_alloc_impl(arc_buf_hdr_t *hdr, spa_t *spa, const zbookmark_phys_t *zb,
ASSERT3P(*ret, ==, NULL);
IMPLY(encrypted, compressed);
hdr->b_l1hdr.b_mru_hits = 0;
hdr->b_l1hdr.b_mru_ghost_hits = 0;
hdr->b_l1hdr.b_mfu_hits = 0;
hdr->b_l1hdr.b_mfu_ghost_hits = 0;
hdr->b_l1hdr.b_l2_hits = 0;
buf = *ret = kmem_cache_alloc(buf_cache, KM_PUSHPAGE);
buf->b_hdr = hdr;
buf->b_data = NULL;
@ -3277,6 +3271,10 @@ arc_hdr_alloc(uint64_t spa, int32_t psize, int32_t lsize,
hdr->b_l1hdr.b_state = arc_anon;
hdr->b_l1hdr.b_arc_access = 0;
hdr->b_l1hdr.b_mru_hits = 0;
hdr->b_l1hdr.b_mru_ghost_hits = 0;
hdr->b_l1hdr.b_mfu_hits = 0;
hdr->b_l1hdr.b_mfu_ghost_hits = 0;
hdr->b_l1hdr.b_bufcnt = 0;
hdr->b_l1hdr.b_buf = NULL;
@ -3460,7 +3458,6 @@ arc_hdr_realloc_crypt(arc_buf_hdr_t *hdr, boolean_t need_crypt)
nhdr->b_l1hdr.b_mru_ghost_hits = hdr->b_l1hdr.b_mru_ghost_hits;
nhdr->b_l1hdr.b_mfu_hits = hdr->b_l1hdr.b_mfu_hits;
nhdr->b_l1hdr.b_mfu_ghost_hits = hdr->b_l1hdr.b_mfu_ghost_hits;
nhdr->b_l1hdr.b_l2_hits = hdr->b_l1hdr.b_l2_hits;
nhdr->b_l1hdr.b_acb = hdr->b_l1hdr.b_acb;
nhdr->b_l1hdr.b_pabd = hdr->b_l1hdr.b_pabd;
@ -3505,7 +3502,6 @@ arc_hdr_realloc_crypt(arc_buf_hdr_t *hdr, boolean_t need_crypt)
hdr->b_l1hdr.b_mru_ghost_hits = 0;
hdr->b_l1hdr.b_mfu_hits = 0;
hdr->b_l1hdr.b_mfu_ghost_hits = 0;
hdr->b_l1hdr.b_l2_hits = 0;
hdr->b_l1hdr.b_acb = NULL;
hdr->b_l1hdr.b_pabd = NULL;
@ -5427,7 +5423,7 @@ arc_access(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
arc_hdr_clear_flags(hdr,
ARC_FLAG_PREFETCH |
ARC_FLAG_PRESCIENT_PREFETCH);
atomic_inc_32(&hdr->b_l1hdr.b_mru_hits);
hdr->b_l1hdr.b_mru_hits++;
ARCSTAT_BUMP(arcstat_mru_hits);
if (HDR_HAS_L2HDR(hdr))
l2arc_hdr_arcstats_increment_state(hdr);
@ -5452,7 +5448,7 @@ arc_access(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, hdr);
arc_change_state(arc_mfu, hdr, hash_lock);
}
atomic_inc_32(&hdr->b_l1hdr.b_mru_hits);
hdr->b_l1hdr.b_mru_hits++;
ARCSTAT_BUMP(arcstat_mru_hits);
} else if (hdr->b_l1hdr.b_state == arc_mru_ghost) {
arc_state_t *new_state;
@ -5481,7 +5477,7 @@ arc_access(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
hdr->b_l1hdr.b_arc_access = ddi_get_lbolt();
arc_change_state(new_state, hdr, hash_lock);
atomic_inc_32(&hdr->b_l1hdr.b_mru_ghost_hits);
hdr->b_l1hdr.b_mru_ghost_hits++;
ARCSTAT_BUMP(arcstat_mru_ghost_hits);
} else if (hdr->b_l1hdr.b_state == arc_mfu) {
/*
@ -5494,7 +5490,7 @@ arc_access(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
* the head of the list now.
*/
atomic_inc_32(&hdr->b_l1hdr.b_mfu_hits);
hdr->b_l1hdr.b_mfu_hits++;
ARCSTAT_BUMP(arcstat_mfu_hits);
hdr->b_l1hdr.b_arc_access = ddi_get_lbolt();
} else if (hdr->b_l1hdr.b_state == arc_mfu_ghost) {
@ -5517,7 +5513,7 @@ arc_access(arc_buf_hdr_t *hdr, kmutex_t *hash_lock)
DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, hdr);
arc_change_state(new_state, hdr, hash_lock);
atomic_inc_32(&hdr->b_l1hdr.b_mfu_ghost_hits);
hdr->b_l1hdr.b_mfu_ghost_hits++;
ARCSTAT_BUMP(arcstat_mfu_ghost_hits);
} else if (hdr->b_l1hdr.b_state == arc_l2c_only) {
/*
@ -6288,7 +6284,7 @@ top:
DTRACE_PROBE1(l2arc__hit, arc_buf_hdr_t *, hdr);
ARCSTAT_BUMP(arcstat_l2_hits);
atomic_inc_32(&hdr->b_l2hdr.b_hits);
hdr->b_l2hdr.b_hits++;
cb = kmem_zalloc(sizeof (l2arc_read_callback_t),
KM_SLEEP);
@ -6695,11 +6691,6 @@ arc_release(arc_buf_t *buf, void *tag)
nhdr->b_l1hdr.b_bufcnt = 1;
if (ARC_BUF_ENCRYPTED(buf))
nhdr->b_crypt_hdr.b_ebufcnt = 1;
nhdr->b_l1hdr.b_mru_hits = 0;
nhdr->b_l1hdr.b_mru_ghost_hits = 0;
nhdr->b_l1hdr.b_mfu_hits = 0;
nhdr->b_l1hdr.b_mfu_ghost_hits = 0;
nhdr->b_l1hdr.b_l2_hits = 0;
(void) zfs_refcount_add(&nhdr->b_l1hdr.b_refcnt, tag);
buf->b_hdr = nhdr;
@ -6716,7 +6707,6 @@ arc_release(arc_buf_t *buf, void *tag)
hdr->b_l1hdr.b_mru_ghost_hits = 0;
hdr->b_l1hdr.b_mfu_hits = 0;
hdr->b_l1hdr.b_mfu_ghost_hits = 0;
hdr->b_l1hdr.b_l2_hits = 0;
arc_change_state(arc_anon, hdr, hash_lock);
hdr->b_l1hdr.b_arc_access = 0;