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Restore ARC MFU/MRU pressure

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Before r305323 (MFV r302991: 6950 ARC should cache compressed data)
arc_read() code did this for access to a ghost buffer:
 arc_adapt() (from arc_get_data_buf())
 arc_access(hdr, hash_lock)
I.e., we first checked access to the MFU ghost/MRU ghost buffer and
adapt MFU/MRU sizes (in arc_adapt()) and next move buffer from the ghost
state to regular.

After r305323 the sequence is different:
 arc_access(hdr, hash_lock);
 arc_hdr_alloc_pabd(hdr);
I.e., we first move the buffer from the ghost state in arc_access() and
then we check access to buffer in ghost state (in arc_hdr_alloc_pabd()
-> arc_get_data_abd() -> arc_get_data_impl() -> arc_adapt()).  This is
incorrect: arc_adapt() never see access to the ghost buffer because
arc_access() already migrated the buffer from the ghost state to
regular.

So, the fix is to restore a call to arc_adapt() before arc_access() and
to suppress the call to arc_adapt() after arc_access().

Submitted by:	Slawa Olhovchenkov <slw@zxy.spb.ru>
MFC after:	2 weeks
Sponsored by:	Integros [integros.com]
Differential Revision: https://reviews.freebsd.org/D19094
This commit is contained in:
Andriy Gapon 2019-06-07 06:35:42 +00:00
parent 27c3a85d07
commit d8b12a2162
1 changed files with 16 additions and 14 deletions
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30
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
View File

@ -1560,14 +1560,14 @@ static kmutex_t l2arc_feed_thr_lock;
static kcondvar_t l2arc_feed_thr_cv;
static uint8_t l2arc_thread_exit;
static abd_t *arc_get_data_abd(arc_buf_hdr_t *, uint64_t, void *);
static abd_t *arc_get_data_abd(arc_buf_hdr_t *, uint64_t, void *, boolean_t);
static void *arc_get_data_buf(arc_buf_hdr_t *, uint64_t, void *);
static void arc_get_data_impl(arc_buf_hdr_t *, uint64_t, void *);
static void arc_get_data_impl(arc_buf_hdr_t *, uint64_t, void *, boolean_t);
static void arc_free_data_abd(arc_buf_hdr_t *, abd_t *, uint64_t, void *);
static void arc_free_data_buf(arc_buf_hdr_t *, void *, uint64_t, void *);
static void arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag);
static void arc_hdr_free_pabd(arc_buf_hdr_t *);
static void arc_hdr_alloc_pabd(arc_buf_hdr_t *);
static void arc_hdr_alloc_pabd(arc_buf_hdr_t *, boolean_t);
static void arc_access(arc_buf_hdr_t *, kmutex_t *);
static boolean_t arc_is_overflowing();
static void arc_buf_watch(arc_buf_t *);
@ -3353,14 +3353,14 @@ arc_buf_destroy_impl(arc_buf_t *buf)
}
static void
arc_hdr_alloc_pabd(arc_buf_hdr_t *hdr)
arc_hdr_alloc_pabd(arc_buf_hdr_t *hdr, boolean_t do_adapt)
{
ASSERT3U(HDR_GET_LSIZE(hdr), >, 0);
ASSERT(HDR_HAS_L1HDR(hdr));
ASSERT(!HDR_SHARED_DATA(hdr));
ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
hdr->b_l1hdr.b_pabd = arc_get_data_abd(hdr, arc_hdr_size(hdr), hdr);
hdr->b_l1hdr.b_pabd = arc_get_data_abd(hdr, arc_hdr_size(hdr), hdr, do_adapt);
hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
@ -3424,7 +3424,7 @@ arc_hdr_alloc(uint64_t spa, int32_t psize, int32_t lsize,
* the compressed or uncompressed data depending on the block
* it references and compressed arc enablement.
*/
arc_hdr_alloc_pabd(hdr);
arc_hdr_alloc_pabd(hdr, B_TRUE);
ASSERT(refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
return (hdr);
@ -5145,11 +5145,11 @@ arc_is_overflowing(void)
}
static abd_t *
arc_get_data_abd(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
arc_get_data_abd(arc_buf_hdr_t *hdr, uint64_t size, void *tag, boolean_t do_adapt)
{
arc_buf_contents_t type = arc_buf_type(hdr);
arc_get_data_impl(hdr, size, tag);
arc_get_data_impl(hdr, size, tag, do_adapt);
if (type == ARC_BUFC_METADATA) {
return (abd_alloc(size, B_TRUE));
} else {
@ -5163,7 +5163,7 @@ arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
{
arc_buf_contents_t type = arc_buf_type(hdr);
arc_get_data_impl(hdr, size, tag);
arc_get_data_impl(hdr, size, tag, B_TRUE);
if (type == ARC_BUFC_METADATA) {
return (zio_buf_alloc(size));
} else {
@ -5179,12 +5179,13 @@ arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
* limit, we'll only signal the reclaim thread and continue on.
*/
static void
arc_get_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
arc_get_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag, boolean_t do_adapt)
{
arc_state_t *state = hdr->b_l1hdr.b_state;
arc_buf_contents_t type = arc_buf_type(hdr);
arc_adapt(size, state);
if (do_adapt)
arc_adapt(size, state);
/*
* If arc_size is currently overflowing, and has grown past our
@ -5935,8 +5936,9 @@ top:
* do this after we've called arc_access() to
* avoid hitting an assert in remove_reference().
*/
arc_adapt(arc_hdr_size(hdr), hdr->b_l1hdr.b_state);
arc_access(hdr, hash_lock);
arc_hdr_alloc_pabd(hdr);
arc_hdr_alloc_pabd(hdr, B_FALSE);
}
ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
size = arc_hdr_size(hdr);
@ -6350,7 +6352,7 @@ arc_release(arc_buf_t *buf, void *tag)
if (arc_can_share(hdr, lastbuf)) {
arc_share_buf(hdr, lastbuf);
} else {
arc_hdr_alloc_pabd(hdr);
arc_hdr_alloc_pabd(hdr, B_TRUE);
abd_copy_from_buf(hdr->b_l1hdr.b_pabd,
buf->b_data, psize);
}
@ -6513,7 +6515,7 @@ arc_write_ready(zio_t *zio)
* the data into it; otherwise, we share the data directly if we can.
*/
if (zfs_abd_scatter_enabled || !arc_can_share(hdr, buf)) {
arc_hdr_alloc_pabd(hdr);
arc_hdr_alloc_pabd(hdr, B_TRUE);
/*
* Ideally, we would always copy the io_abd into b_pabd, but the