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Pack dmu_buf_impl_t by 16 bytes

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On 64bit FreeBSD this reduces one from 296 to 280 bytes.  On small
block workloads dbufs may consume gigabytes of ARC, and this saves
5% of it.

Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #16684
This commit is contained in:
Alexander Motin 2024-10-25 12:03:37 -04:00 committed by GitHub
parent 2e4e092822
commit 94a03dd1e4
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GPG Key ID: B5690EEEBB952194
1 changed files with 24 additions and 29 deletions
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53
include/sys/dbuf.h
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@ -264,6 +264,27 @@ typedef struct dmu_buf_impl {
*/
uint8_t db_level;
/* This block was freed while a read or write was active. */
uint8_t db_freed_in_flight;
/*
* Evict user data as soon as the dirty and reference counts are equal.
*/
uint8_t db_user_immediate_evict;
/*
* dnode_evict_dbufs() or dnode_evict_bonus() tried to evict this dbuf,
* but couldn't due to outstanding references. Evict once the refcount
* drops to 0.
*/
uint8_t db_pending_evict;
/* Number of TXGs in which this buffer is dirty. */
uint8_t db_dirtycnt;
/* The buffer was partially read. More reads may follow. */
uint8_t db_partial_read;
/*
* Protects db_buf's contents if they contain an indirect block or data
* block of the meta-dnode. We use this lock to protect the structure of
@ -288,6 +309,9 @@ typedef struct dmu_buf_impl {
*/
dbuf_states_t db_state;
/* In which dbuf cache this dbuf is, if any. */
dbuf_cached_state_t db_caching_status;
/*
* Refcount accessed by dmu_buf_{hold,rele}.
* If nonzero, the buffer can't be destroyed.
@ -304,39 +328,10 @@ typedef struct dmu_buf_impl {
/* Link in dbuf_cache or dbuf_metadata_cache */
multilist_node_t db_cache_link;
/* Tells us which dbuf cache this dbuf is in, if any */
dbuf_cached_state_t db_caching_status;
uint64_t db_hash;
/* Data which is unique to data (leaf) blocks: */
/* User callback information. */
dmu_buf_user_t *db_user;
/*
* Evict user data as soon as the dirty and reference
* counts are equal.
*/
uint8_t db_user_immediate_evict;
/*
* This block was freed while a read or write was
* active.
*/
uint8_t db_freed_in_flight;
/*
* dnode_evict_dbufs() or dnode_evict_bonus() tried to
* evict this dbuf, but couldn't due to outstanding
* references. Evict once the refcount drops to 0.
*/
uint8_t db_pending_evict;
uint8_t db_dirtycnt;
/* The buffer was partially read. More reads may follow. */
uint8_t db_partial_read;
} dmu_buf_impl_t;
#define DBUF_HASH_MUTEX(h, idx) \