linux/Documentation
brookxu 27bc446e2d ext4: limit the length of per-inode prealloc list
In the scenario of writing sparse files, the per-inode prealloc list may
be very long, resulting in high overhead for ext4_mb_use_preallocated().
To circumvent this problem, we limit the maximum length of per-inode
prealloc list to 512 and allow users to modify it.

After patching, we observed that the sys ratio of cpu has dropped, and
the system throughput has increased significantly. We created a process
to write the sparse file, and the running time of the process on the
fixed kernel was significantly reduced, as follows:

Running time on unfixed kernel:
[root@TENCENT64 ~]# time taskset 0x01 ./sparse /data1/sparce.dat
real    0m2.051s
user    0m0.008s
sys     0m2.026s

Running time on fixed kernel:
[root@TENCENT64 ~]# time taskset 0x01 ./sparse /data1/sparce.dat
real    0m0.471s
user    0m0.004s
sys     0m0.395s

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Link: https://lore.kernel.org/r/d7a98178-056b-6db5-6bce-4ead23f4a257@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2020-08-19 12:04:36 -04:00
..
ABI USB fixes for 5.8-rc3 2020-06-27 13:12:10 -07:00
accounting
admin-guide ext4: limit the length of per-inode prealloc list 2020-08-19 12:04:36 -04:00
arm
arm64 arm64: Add KRYO4XX silver CPU cores to erratum list 1530923 and 1024718 2020-07-03 16:39:16 +01:00
block for-5.8-tag 2020-06-02 19:59:25 -07:00
bpf bpf: Document optval > PAGE_SIZE behavior for sockopt hooks 2020-06-17 10:54:05 -07:00
cdrom
core-api docs: mm/gup: minor documentation update 2020-06-26 00:27:37 -07:00
cpu-freq
crypto
dev-tools linux-kselftest-kunit-fixes-5.8-rc4 2020-07-02 21:49:26 -07:00
devicetree Devicetree fixes for v5.8, take 2: 2020-07-02 22:46:05 -07:00
doc-guide A handful of late-arriving docs fixes, along with a patch changing a lot of 2020-06-10 14:12:15 -07:00
driver-api Documentation: media: convert to use i2c_new_client_device() 2020-06-19 09:20:25 +02:00
fault-injection
fb media updates for v5.8-rc1 2020-06-03 20:59:38 -07:00
features mm/debug: add tests validating architecture page table helpers 2020-06-04 19:06:21 -07:00
filesystems ext4: replace HTTP links with HTTPS ones 2020-08-06 01:01:57 -04:00
firmware_class
firmware-guide
fpga
gpu drm/amdgpu: fix documentation around busy_percentage 2020-06-17 17:42:43 -04:00
hid
hwmon Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2020-06-03 16:27:18 -07:00
i2c i2c: slave-eeprom: update documentation 2020-07-04 08:17:53 +02:00
ia64 docs: add IRQ documentation at the core-api book 2020-05-15 12:00:56 -06:00
ide
iio
infiniband RDMA/core: Remove FMR device ops 2020-06-02 20:32:54 -03:00
input
isdn
kbuild docs: kbuild: fix ReST formatting 2020-06-28 12:16:55 +09:00
kernel-hacking
leds
livepatch
locking A fair amount of stuff this time around, dominated by yet another massive 2020-06-01 15:45:27 -07:00
m68k
maintainer Documentation: fixes to the maintainer-entry-profile template 2020-06-01 09:36:07 -06:00
mhi
mips dt: fix broken links due to txt->yaml renames 2020-06-18 10:45:05 -06:00
misc-devices Replace HTTP links with HTTPS ones: documentation 2020-06-08 09:30:19 -06:00
netlabel
networking docs: net: ieee802154: change link to new project URL 2020-06-19 22:08:09 +02:00
nios2
nvdimm nvdimm: fixes to maintainter-entry-profile 2020-05-25 10:19:19 -06:00
openrisc
parisc
PCI pci-v5.8-changes 2020-06-06 11:01:58 -07:00
pcmcia
power Power management updates for 5.8-rc1 2020-06-02 13:17:23 -07:00
powerpc powerpc: Document details on H_SCM_HEALTH hcall 2020-06-15 18:22:43 -07:00
process Merge branch 'rwonce/rework' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux 2020-06-10 14:46:54 -07:00
RCU
riscv
s390 s390 updates for the 5.8 merge window 2020-06-08 12:05:31 -07:00
scheduler
scsi
security Notifications over pipes + Keyring notifications 2020-06-13 09:56:21 -07:00
sh Documentation: remove SH-5 index entries 2020-06-16 17:39:43 -07:00
sound
sparc
sphinx Replace HTTP links with HTTPS ones: documentation 2020-06-08 09:30:19 -06:00
sphinx-static
spi
target doc: don't use deprecated "---help---" markers in target docs 2020-06-13 13:32:40 -07:00
timers
trace A handful of late-arriving docs fixes, along with a patch changing a lot of 2020-06-10 14:12:15 -07:00
translations A handful of late-arriving docs fixes, along with a patch changing a lot of 2020-06-10 14:12:15 -07:00
usb A fair amount of stuff this time around, dominated by yet another massive 2020-06-01 15:45:27 -07:00
userspace-api Documentation: media: convert to use i2c_new_client_device() 2020-06-19 09:20:25 +02:00
virt ARM: 2020-06-03 15:13:47 -07:00
vm A handful of late-arriving docs fixes, along with a patch changing a lot of 2020-06-10 14:12:15 -07:00
w1 w1_therm: adding bulk read support to trigger multiple conversion on bus 2020-05-15 16:29:00 +02:00
watchdog watchdog: clarify that stop() is optional 2020-05-25 08:55:42 +02:00
x86 A fair amount of stuff this time around, dominated by yet another massive 2020-06-01 15:45:27 -07:00
xtensa
.gitignore
asm-annotations.rst
atomic_bitops.txt
atomic_t.txt
bus-virt-phys-mapping.txt
Changes
CodingStyle
conf.py Replace HTTP links with HTTPS ones: documentation 2020-06-08 09:30:19 -06:00
COPYING-logo Replace HTTP links with HTTPS ones: documentation 2020-06-08 09:30:19 -06:00
crc32.txt
docutils.conf
dontdiff modpost: generate vmlinux.symvers and reuse it for the second modpost 2020-06-06 23:38:12 +09:00
index.rst Devicetree updates for v5.8: 2020-06-04 20:11:25 -07:00
Kconfig
kprobes.txt
logo.gif
lzo.txt lib/lzo: fix ambiguous encoding bug in lzo-rle 2020-06-11 18:17:47 -07:00
mailbox.txt
Makefile media updates for v5.8-rc1 2020-06-03 20:59:38 -07:00
memory-barriers.txt
nommu-mmap.txt
remoteproc.txt
rpmsg.txt
speculation.txt
static-keys.txt Replace HTTP links with HTTPS ones: documentation 2020-06-08 09:30:19 -06:00
SubmittingPatches
tee.txt
this_cpu_ops.txt
watch_queue.rst pipe: Add general notification queue support 2020-05-19 15:08:24 +01:00
xz.txt Replace HTTP links with HTTPS ones: documentation 2020-06-08 09:30:19 -06:00