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3f74e6bd3b
set_initial_priority() tries to jump-start global reclaim by estimating
the priority based on cold/hot LRU pages. The estimation does not account
for shrinker objects, and it cannot do so because their sizes can be in
different units other than page.
If shrinker objects are the majority, e.g., on TrueNAS SCALE 24.04.0 where
ZFS ARC can use almost all system memory, set_initial_priority() can
vastly underestimate how much memory ARC shrinker can evict and assign
extreme low values to scan_control->priority, resulting in overshoots of
shrinker objects.
To reproduce the problem, using TrueNAS SCALE 24.04.0 with 32GB DRAM, a
test ZFS pool and the following commands:
fio --name=mglru.file --numjobs=36 --ioengine=io_uring \
--directory=/root/test-zfs-pool/ --size=1024m --buffered=1 \
--rw=randread --random_distribution=random \
--time_based --runtime=1h &
for ((i = 0; i < 20; i++))
do
sleep 120
fio --name=mglru.anon --numjobs=16 --ioengine=mmap \
--filename=/dev/zero --size=1024m --fadvise_hint=0 \
--rw=randrw --random_distribution=random \
--time_based --runtime=1m
done
To fix the problem:
1. Cap scan_control->priority at or above DEF_PRIORITY/2, to prevent
the jump-start from being overly aggressive.
2. Account for the progress from mm_account_reclaimed_pages(), to
prevent kswapd_shrink_node() from raising the priority
unnecessarily.
Link: https://lkml.kernel.org/r/20240711191957.939105-2-yuzhao@google.com
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.