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Alex Zhuravlev c1d2c7d47e ext4: skip non-loaded groups at cr=0/1 when scanning for good groups
cr=0 is supposed to be an optimization to save CPU cycles, but if
buddy data (in memory) is not initialized then all this makes no sense
as we have to do sync IO taking a lot of cycles.  Also, at cr=0
mballoc doesn't choose any available chunk.  cr=1 also skips groups
using heuristic based on avg. fragment size.  It's more useful to skip
such groups and switch to cr=2 where groups will be scanned for
available chunks.  However, we always read the first block group in a
flex_bg so metadata blocks will get read into the first flex_bg if
possible.

Using sparse image and dm-slow virtual device of 120TB was
simulated, then the image was formatted and filled using debugfs to
mark ~85% of available space as busy.  mount process w/o the patch
couldn't complete in half an hour (according to vmstat it would take
~10-11 hours).  With the patch applied mount took ~20 seconds.

Lustre-bug-id: https://jira.whamcloud.com/browse/LU-12988
Signed-off-by: Alex Zhuravlev <azhuravlev@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
2020-08-06 01:44:55 -04:00
arch x86/ldt: use "pr_info_once()" instead of open-coding it badly 2020-07-05 12:50:20 -07:00
block block-5.8-2020-07-05 2020-07-05 10:45:31 -07:00
certs
crypto
Documentation ext4: use generic names for generic ioctls 2020-08-06 01:35:05 -04:00
drivers A set of interrupt chip driver fixes: 2020-07-05 12:22:35 -07:00
fs ext4: skip non-loaded groups at cr=0/1 when scanning for good groups 2020-08-06 01:44:55 -04:00
include pci-v5.8-fixes-1 2020-07-03 12:14:51 -07:00
init kbuild: fix CONFIG_CC_CAN_LINK(_STATIC) for cross-compilation with Clang 2020-07-02 00:57:45 +09:00
ipc
kernel A single fix for a printk format warning in RCU. 2020-07-05 12:21:28 -07:00
lib Peter Zijlstra says: 2020-06-28 09:42:47 -07:00
LICENSES
mm mm/page_alloc: fix documentation error 2020-07-03 16:15:25 -07:00
net Fixes for a umask bug on exported filesystems lacking ACL support, a 2020-07-02 20:35:33 -07:00
samples samples/vfs: avoid warning in statx override 2020-07-03 16:15:25 -07:00
scripts Kbuild fixes for v5.8 (2nd) 2020-07-05 12:14:24 -07:00
security Two simple fixes for v5.8: 2020-06-30 12:21:53 -07:00
sound sound fixes for 5.8-rc3 2020-06-25 09:15:24 -07:00
tools A series of fixes for x86: 2020-07-05 12:23:49 -07:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: Do not track defconfig from make savedefconfig 2020-07-05 16:15:46 +09:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Devicetree fixes for v5.8, take 2: 2020-07-02 22:46:05 -07:00
Makefile Linux 5.8-rc4 2020-07-05 16:20:22 -07:00
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 Restructured Text 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.