linux/Documentation
zhouxianrong 8e19d540d1 zram: extend zero pages to same element pages
The idea is that without doing more calculations we extend zero pages to
same element pages for zram.  zero page is special case of same element
page with zero element.

1. the test is done under android 7.0
2. startup too many applications circularly
3. sample the zero pages, same pages (none-zero element)
   and total pages in function page_zero_filled

the result is listed as below:

ZERO	SAME	TOTAL
36214	17842	598196

		ZERO/TOTAL	 SAME/TOTAL	  (ZERO+SAME)/TOTAL ZERO/SAME
AVERAGE	0.060631909	 0.024990816  0.085622726		2.663825038
STDEV	0.00674612	 0.005887625  0.009707034		2.115881328
MAX		0.069698422	 0.030046087  0.094975336		7.56043956
MIN		0.03959586	 0.007332205  0.056055193		1.928985507

from the above data, the benefit is about 2.5% and up to 3% of total
swapout pages.

The defect of the patch is that when we recovery a page from non-zero
element the operations are low efficient for partial read.

This patch extends zero_page to same_page so if there is any user to
have monitored zero_pages, he will be surprised if the number is
increased but it's not harmful, I believe.

[minchan@kernel.org: do not free same element pages in zram_meta_free]
  Link: http://lkml.kernel.org/r/20170207065741.GA2567@bbox
Link: http://lkml.kernel.org/r/1483692145-75357-1-git-send-email-zhouxianrong@huawei.com
Link: http://lkml.kernel.org/r/1486307804-27903-1-git-send-email-minchan@kernel.org
Signed-off-by: zhouxianrong <zhouxianrong@huawei.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24 17:46:56 -08:00
..
ABI First set of updates for 4.11 kernel merge window 2017-02-23 08:27:57 -08:00
accounting
acpi
admin-guide Merge branch 'akpm' (patches from Andrew) 2017-02-22 19:29:24 -08:00
aoe
arm
arm64 arm64: Work around Falkor erratum 1003 2017-02-10 11:22:12 +00:00
auxdisplay
backlight
blackfin
block A slightly quieter cycle for documentation this time around. 2017-02-22 18:51:29 -08:00
blockdev zram: extend zero pages to same element pages 2017-02-24 17:46:56 -08:00
bus-devices
cdrom cdrom: Make device operations read-only 2017-02-14 08:29:56 -07:00
cgroup-v1
cma
connector
console
core-api
cpu-freq A slightly quieter cycle for documentation this time around. 2017-02-22 18:51:29 -08:00
cpuidle
cris
crypto crypto: doc - fix typo 2017-02-15 13:23:49 +08:00
dev-tools Improve sparse documentation 2017-02-15 15:09:13 -07:00
device-mapper dm cache metadata: add "metadata2" feature 2017-02-16 13:12:47 -05:00
devicetree Less anger inducing pull request for 4.11 2017-02-23 18:58:18 -08:00
dmaengine
doc-guide
DocBook A slightly quieter cycle for documentation this time around. 2017-02-22 18:51:29 -08:00
driver-api Less anger inducing pull request for 4.11 2017-02-23 18:58:18 -08:00
driver-model irqdesc: Add a resource managed version of irq_alloc_descs() 2017-02-10 14:39:20 +01:00
early-userspace
EDID
extcon
fault-injection
fb
features
filesystems rxrpc: Change module filename to rxrpc.ko 2017-02-17 15:09:19 -05:00
firmware_class
fmc
fpga fpga: Add scatterlist based programming 2017-02-10 15:20:44 +01:00
frv
gpio
gpu Less anger inducing pull request for 4.11 2017-02-23 18:58:18 -08:00
hid
hwmon A slightly quieter cycle for documentation this time around. 2017-02-22 18:51:29 -08:00
i2c
ia64
ide
iio
infiniband
input Documentation: input: fix path to input code definitions 2017-02-12 15:19:00 -07:00
ioctl rpmsg updates for v4.11 2017-02-23 09:41:03 -08:00
isdn
kbuild
kdump
laptops
leds
livepatch A slightly quieter cycle for documentation this time around. 2017-02-22 18:51:29 -08:00
locking
m68k
media A slightly quieter cycle for documentation this time around. 2017-02-22 18:51:29 -08:00
memory-devices
metag
mic
mips
misc-devices
mmc
mn10300
mtd
namespaces
netlabel
networking A slightly quieter cycle for documentation this time around. 2017-02-22 18:51:29 -08:00
nfc
nios2
nvdimm
nvmem
parisc
PCI Merge branch 'pci/msi' into next 2017-02-15 11:56:10 -06:00
pcmcia
perf
phy
platform
power A slightly quieter cycle for documentation this time around. 2017-02-22 18:51:29 -08:00
powerpc
pps
prctl
process
pti
ptp
rapidio
RCU
s390
scheduler
scsi
security This renames the (now inaccurate) CONFIG_DEBUG_RODATA and related config 2017-02-21 17:56:45 -08:00
serial
sh
sound
sphinx
sphinx-static
spi spi: spi-ep93xx: simplify GPIO chip selects 2017-02-16 20:10:26 +00:00
sysctl mm, madvise: fail with ENOMEM when splitting vma will hit max_map_count 2017-02-24 17:46:55 -08:00
target
thermal
timers time: Remove CONFIG_TIMER_STATS 2017-02-10 11:15:08 +01:00
trace trace-vmscan-postprocess: sync with tracepoints updates 2017-02-22 16:41:29 -08:00
translations Documentation: Fix linux-api list typo 2017-02-15 15:12:26 -07:00
usb A slightly quieter cycle for documentation this time around. 2017-02-22 18:51:29 -08:00
virtual KVM: race-free exit from KVM_RUN without POSIX signals 2017-02-17 12:27:37 +01:00
vm mm, madvise: fail with ENOMEM when splitting vma will hit max_map_count 2017-02-24 17:46:55 -08:00
w1
watchdog
wimax
x86
xtensa
.gitignore
00-INDEX
bcache.txt
bt8xxgpio.txt
btmrvl.txt
bus-virt-phys-mapping.txt
cachetlb.txt
cgroup-v2.txt
Changes
circular-buffers.txt
clk.txt
CodingStyle
conf.py
cpu-load.txt
cputopology.txt
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt
digsig.txt
DMA-API-HOWTO.txt
DMA-API.txt
DMA-attributes.txt
DMA-ISA-LPC.txt Documentation: DMA-ISA-LPC.txt 2017-02-12 15:20:07 -07:00
docutils.conf
dontdiff
efi-stub.txt
eisa.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcc-plugins.txt
highuid.txt
hw_random.txt
hwspinlock.txt
index.rst
intel_txt.txt
Intel-IOMMU.txt
io_ordering.txt
io-mapping.txt
iostats.txt
IPMI.txt
IRQ-affinity.txt
IRQ-domain.txt
IRQ.txt
irqflags-tracing.txt
isa.txt
isapnp.txt
kernel-doc-nano-HOWTO.txt
kernel-per-CPU-kthreads.txt
kobject.txt
kprobes.txt
kref.txt
kselftest.txt
ldm.txt
lockup-watchdogs.txt
logo.gif
logo.txt
lzo.txt
mailbox.txt
Makefile
Makefile.sphinx Add a target to check broken external links in the Documentation 2017-02-15 15:22:47 -07:00
md-cluster.txt
memory-barriers.txt
memory-hotplug.txt
men-chameleon-bus.txt
nommu-mmap.txt
ntb.txt
numastat.txt
padata.txt
parport-lowlevel.txt
percpu-rw-semaphore.txt
phy.txt
pi-futex.txt
pinctrl.txt
pnp.txt
preempt-locking.txt
printk-formats.txt
pwm.txt
rbtree.txt
remoteproc.txt
rfkill.txt
robust-futex-ABI.txt
robust-futexes.txt
rpmsg.txt
rtc.txt
SAK.txt
sgi-ioc4.txt
siphash.txt
SM501.txt
smsc_ece1099.txt
static-keys.txt
SubmittingPatches
svga.txt
sync_file.txt
this_cpu_ops.txt
unaligned-memory-access.txt
unshare.txt
vfio-mediated-device.txt
vfio.txt
video-output.txt
xillybus.txt
xz.txt
zorro.txt