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Filipe Manana 1020443840 btrfs: make the extent map shrinker run asynchronously as a work queue job
Currently the extent map shrinker is run synchronously for kswapd tasks
that end up calling the fs shrinker (fs/super.c:super_cache_scan()).
This has some disadvantages and for some heavy workloads with memory
pressure it can cause some delays and stalls that make a machine
unresponsive for some periods. This happens because:

1) We can have several kswapd tasks on machines with multiple NUMA zones,
   and running the extent map shrinker concurrently can cause high
   contention on some spin locks, namely the spin locks that protect
   the radix tree that tracks roots, the per root xarray that tracks
   open inodes and the list of delayed iputs. This not only delays the
   shrinker but also causes high CPU consumption and makes the task
   running the shrinker monopolize a core, resulting in the symptoms
   of an unresponsive system. This was noted in previous commits such as
   commit ae1e766f62 ("btrfs: only run the extent map shrinker from
   kswapd tasks");

2) The extent map shrinker's iteration over inodes can often be slow, even
   after changing the data structure that tracks open inodes for a root
   from a red black tree (up to kernel 6.10) to an xarray (kernel 6.10+).
   The transition to the xarray while it made things a bit faster, it's
   still somewhat slow - for example in a test scenario with 10000 inodes
   that have no extent maps loaded, the extent map shrinker took between
   5ms to 8ms, using a release, non-debug kernel. Iterating over the
   extent maps of an inode can also be slow if have an inode with many
   thousands of extent maps, since we use a red black tree to track and
   search extent maps. So having the extent map shrinker run synchronously
   adds extra delay for other things a kswapd task does.

So make the extent map shrinker run asynchronously as a job for the
system unbounded workqueue, just like what we do for data and metadata
space reclaim jobs.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:17 +01:00
arch 20 hotfixes, 14 of which are cc:stable. 2024-11-10 09:04:27 -08:00
block block-6.12-20241101 2024-11-01 13:41:55 -10:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes the following issues: 2024-10-16 08:42:54 -07:00
Documentation 20 hotfixes, 14 of which are cc:stable. 2024-11-10 09:04:27 -08:00
drivers A handful of Qualcomm clk driver fixes: 2024-11-10 14:16:28 -08:00
fs btrfs: make the extent map shrinker run asynchronously as a work queue job 2024-11-11 14:34:17 +01:00
include btrfs: remove unused btrfs_try_tree_write_lock() 2024-11-11 14:34:14 +01:00
init cfi: fix conditions for HAVE_CFI_ICALL_NORMALIZE_INTEGERS 2024-10-13 22:23:13 +02:00
io_uring io_uring/rw: fix missing NOWAIT check for O_DIRECT start write 2024-10-31 08:21:02 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel 20 hotfixes, 14 of which are cc:stable. 2024-11-10 09:04:27 -08:00
lib objpool: fix to make percpu slot allocation more robust 2024-11-07 14:14:58 -08:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm filemap: Fix bounds checking in filemap_read() 2024-11-10 14:07:08 -08:00
net Including fixes from can and netfilter. 2024-11-07 11:07:57 -10:00
rust Driver core fix for 6.12-rc3 2024-10-13 09:10:52 -07:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts Kbuild fixes for v6.12 (2nd) 2024-11-03 08:29:02 -10:00
security KEYS: trusted: dcp: fix NULL dereference in AEAD crypto operation 2024-11-04 21:24:24 +02:00
sound ASoC: Fixes for v6.12 2024-11-08 09:25:33 +01:00
tools 20 hotfixes, 14 of which are cc:stable. 2024-11-10 09:04:27 -08:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt ARM64: 2024-10-21 11:22:04 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS sound fixes for 6.12-rc7 2024-11-08 07:44:28 -10:00
Makefile Linux 6.12-rc7 2024-11-10 14:19:35 -08:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.