mirror_zfs/module
Rob Norris cd69ba3d49 ddt: dedup log
Adds a log/journal to dedup. At the end of txg, instead of writing the
entry directly to the ZAP, instead its adding to an in-memory tree and
appended to an on-disk object. The on-disk object is only read at
import, to reload the in-memory tree.

Lookups first go the the log tree before going to the ZAP, so
recently-used entries will remain close by in memory. This vastly
reduces overhead from dedup IO, as it will not have to do so many
read/update/write cycles on ZAP leaf nodes.

A flushing facility is added at end of txg, to push logged entries out
to the ZAP. There's actually two separate "logs" (in-memory tree and
on-disk object), one active (recieving updated entries) and one flushing
(writing out to disk). These are swapped (ie flushing begins) based on
memory used by the in-memory log trees and time since we last flushed
something.

The flushing facility monitors the amount of entries coming in and being
flushed out, and calibrates itself to try to flush enough each txg to
keep up with the ingest rate without competing too much with other IO.
Multiple tuneables are provided to control the flushing facility.

All the histograms and stats are update to accomodate the log as a
separate entry store. zdb gains knowledge of how to count them and dump
them. Documentation included!

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Allan Jude <allan@klarasystems.com>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Sponsored-by: Klara, Inc.
Sponsored-by: iXsystems, Inc.
Closes #15895
2024-08-16 12:03:35 -07:00
..
avl Suppress Clang Static Analyzer false positive in the AVL tree code. 2023-03-08 13:51:21 -08:00
icp icp: remove redundant FreeBSD check 2024-05-31 15:13:59 -07:00
lua LUA: Backport CVE-2020-24370's patch 2024-02-07 11:53:05 -08:00
nvpair xdr: header cleanup 2024-04-03 15:13:27 -07:00
os linux/zvol_os: fix zvol queue limits initialization 2024-08-15 14:29:50 -07:00
unicode Illumos #15286: do_composition() needs sign awareness 2023-01-05 11:16:21 -08:00
zcommon ddt: add FDT feature and support for legacy and new on-disk formats 2024-08-16 11:58:59 -07:00
zfs ddt: dedup log 2024-08-16 12:03:35 -07:00
zstd zstd: don't call zstd_mempool_reap if there are no buffers (#16302) 2024-07-15 14:51:37 -07:00
.gitignore FreeBSD: Ignore symlink to i386 includes 2022-08-02 16:34:23 -07:00
Kbuild.in ddt: dedup log 2024-08-16 12:03:35 -07:00
Makefile.bsd ddt: dedup log 2024-08-16 12:03:35 -07:00
Makefile.in check-zstd-symbols: also ignore __pfx_ symbols 2023-09-18 09:08:41 -07:00