linux/Documentation
Minchan Kim bb416d18b8 zram: writeback throttle
If there are lots of write IO with flash device, it could have a
wearout problem of storage. To overcome the problem, admin needs
to design write limitation to guarantee flash health
for entire product life.

This patch creates a new knob "writeback_limit" for zram.

writeback_limit's default value is 0 so that it doesn't limit
any writeback. If admin want to measure writeback count in a
certain period, he could know it via /sys/block/zram0/bd_stat's
3rd column.

If admin want to limit writeback as per-day 400M, he could do it
like below.

	MB_SHIFT=20
	4K_SHIFT=12
	echo $((400<<MB_SHIFT>>4K_SHIFT)) > \
		/sys/block/zram0/writeback_limit.

If admin want to allow further write again, he could do it like below

	echo 0 > /sys/block/zram0/writeback_limit

If admin want to see remaining writeback budget,

	cat /sys/block/zram0/writeback_limit

The writeback_limit count will reset whenever you reset zram (e.g., system
reboot, echo 1 > /sys/block/zramX/reset) so keeping how many of writeback
happened until you reset the zram to allocate extra writeback budget in
next setting is user's job.

[minchan@kernel.org: v4]
  Link: http://lkml.kernel.org/r/20181203024045.153534-8-minchan@kernel.org
Link: http://lkml.kernel.org/r/20181127055429.251614-8-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Joey Pabalinas <joeypabalinas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:49 -08:00
..
ABI zram: writeback throttle 2018-12-28 12:11:49 -08:00
accelerators ocxl: Document new OCXL IOCTLs 2018-06-03 20:40:33 +10:00
accounting psi: cgroup support 2018-10-26 16:26:32 -07:00
acpi ACPI: property: graph: Update graph documentation to use generic references 2018-07-23 12:44:52 +02:00
admin-guide selinux/stable-4.21 PR 20181224 2018-12-27 12:01:58 -08:00
aoe
arm ARM: SoC device tree updates for 4.20 2018-10-29 15:05:20 -07:00
arm64 arm64 festive updates for 4.21 2018-12-25 17:41:56 -08:00
auxdisplay Doc: misc-devices: move lcd-panel-cgram.txt to auxdisplay/ 2018-04-12 16:08:02 +02:00
backlight
block Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
blockdev zram: writeback throttle 2018-12-28 12:11:49 -08:00
bpf Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2018-08-07 11:02:05 -07:00
bus-devices
cdrom Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
cgroup-v1 Merge branch 'for-4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2018-10-25 17:15:46 -07:00
cma
connector
console Documentation: corrections to console/console.txt 2018-08-10 16:09:40 -06:00
core-api XArray: Add xa_cmpxchg_irq and xa_cmpxchg_bh 2018-12-06 08:26:17 -05:00
cpu-freq Documentation: cpu-freq: Frequencies aren't always sorted 2018-11-07 13:29:04 +01:00
cpuidle Documentation: admin-guide: PM: Add cpuidle document 2018-12-03 10:03:36 +01:00
crypto crypto: skcipher - remove remnants of internal IV generators 2018-12-23 11:52:45 +08:00
dev-tools kasan: update documentation 2018-12-28 12:11:44 -08:00
device-mapper This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
devicetree Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
doc-guide Documentation/sphinx: allow "functions" with no parameters 2018-06-30 07:52:42 -06:00
driver-api docs: driver-api: Add I3C documentation 2018-11-12 10:33:49 +01:00
driver-model gpio: Add devm_gpiod_unhinge() 2018-12-11 01:04:23 +00:00
early-userspace initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
EDID
extcon
fault-injection Documentation: nvme: Documentation for nvme fault injection 2018-03-26 08:53:43 -06:00
fb This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
features MIPS: Enable IOREMAP_PROT config option for MIPS cpus 2018-11-05 10:15:28 -08:00
filesystems This pull request contains updates for UBIFS: 2018-11-04 14:46:04 -08:00
firmware_class
fmc Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
fpga docs: fpga: add a document for FPGA Device Feature List (DFL) Framework Overview 2018-07-15 13:55:44 +02:00
gpio Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
gpu Final changes to drm-misc-next for v4.21: 2018-12-07 11:23:05 +10:00
hid
hwmon hwmon: (ina3221) Read channel input source info from DT 2018-10-10 20:37:13 -07:00
i2c i2c: add i2c bus driver for NVIDIA GPU 2018-11-09 17:46:43 +01:00
ia64
ide Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
iio
infiniband
input Revert "Input: Add the REL_WHEEL_HI_RES event code" 2018-11-22 08:57:44 +01:00
ioctl drm pull for 4.20-rc1 2018-10-28 17:49:53 -07:00
isdn Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
kbuild kbuild: remove unused cc-fullversion variable 2018-11-02 00:15:26 +09:00
kdump
kernel-hacking doc:it_IT: translation for kernel-hacking 2018-07-26 16:21:09 -06:00
laptops platform-drivers-x86 for v4.20-1 2018-11-01 08:42:21 -07:00
leds Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
lightnvm
livepatch livepatch: Remove not longer valid limitations from the documentation 2018-05-24 15:37:57 +02:00
locking This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
m68k Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
maintainer docs: Fix more broken references 2018-06-15 18:11:26 -03:00
md
media media fixes for v4.20-rc8 2018-12-25 13:11:30 -08:00
memory-devices
mic
mips Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
misc-devices pci_endpoint_test: Add 2 ioctl commands 2018-07-19 11:46:57 +01:00
mmc Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
mtd Documentation: mtd: remove stale pxa3xx NAND controller documentation 2018-09-04 23:37:38 +02:00
namespaces
netlabel Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
networking Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next 2018-12-20 18:20:26 -08:00
nfc
nios2
nvdimm
nvmem Documentation: nvmem: document cell tables and lookup entries 2018-09-28 15:14:54 +02:00
openrisc
parisc Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
PCI pci-v4.20-changes 2018-10-25 06:50:48 -07:00
pcmcia pcmcia: remove long deprecated pcmcia_request_exclusive_irq() function 2018-08-18 12:30:42 -07:00
perf Documentation: perf: Add documentation for ThunderX2 PMU uncore driver 2018-12-06 12:29:47 +00:00
phy
platform
power This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
powerpc powerpc/fadump: Reservationless firmware assisted dump 2018-12-21 11:32:49 +11:00
pps
process The Compiler Attributes series 2018-11-01 18:34:46 -07:00
pti
ptp ptp: Fix documentation to match code. 2018-03-26 12:13:21 -04:00
rapidio
RCU doc: Fix "struction" typo in RCU memory-ordering documentation 2018-11-12 08:56:25 -08:00
riscv perf: riscv: Add Document for Future Porting Guide 2018-06-04 14:02:11 -07:00
s390 KVM updates for v4.20 2018-10-25 17:57:35 -07:00
scheduler This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
scsi SCSI misc on 20181024 2018-10-25 07:40:30 -07:00
security Merge branch 'next-keys2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2018-11-01 15:23:59 -07:00
serial TTY/Serial patches for 4.20-rc1 2018-10-29 10:42:20 -07:00
sh
sound ALSA: doc: Brush up the old writing-an-alsa-driver 2018-10-18 10:30:01 +02:00
sparc
sphinx Documentation/sphinx: allow "functions" with no parameters 2018-06-30 07:52:42 -06:00
sphinx-static docs: improve readability for people with poorer eyesight 2018-10-07 09:16:50 -06:00
spi Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
sysctl mm: reclaim small amounts of memory when an external fragmentation event occurs 2018-12-28 12:11:48 -08:00
target
thermal thermal: Add cooling device's statistics in sysfs 2018-04-02 21:49:01 +08:00
timers Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
trace The biggest change here is the updates to kprobes 2018-10-30 09:49:56 -07:00
translations This was a moderately busy cycle for docs, with the usual collection of 2018-08-14 14:29:31 -07:00
usb USB-serial updates for v4.19-rc1 2018-07-20 21:47:15 +02:00
userspace-api x86/speculation: Add prctl() control for indirect branch speculation 2018-11-28 11:57:13 +01:00
virtual x86/kvm/hyper-v: Introduce KVM_GET_SUPPORTED_HV_CPUID 2018-12-14 17:59:54 +01:00
vm Merge drm/drm-next into drm-intel-next-queued 2018-11-20 13:14:08 +02:00
w1 Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00
watchdog documentation: watchdog: add documentation for armada-37xx-wdt 2018-10-13 15:19:40 +02:00
wimax
x86 Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-12-26 12:17:43 -08:00
xilinx Documentation: xilinx: Add documentation for eemi APIs 2018-10-09 13:26:05 +02:00
xtensa
.gitignore
atomic_bitops.txt
atomic_t.txt
bt8xxgpio.txt
btmrvl.txt
bus-virt-phys-mapping.txt
Changes
clearing-warn-once.txt
CodingStyle
conf.py This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
cpu-load.txt
cputopology.txt
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt Documentation: remove stale firmware API reference 2018-05-14 16:44:41 +02:00
digsig.txt
DMA-API-HOWTO.txt
DMA-API.txt
DMA-attributes.txt
DMA-ISA-LPC.txt
docutils.conf
dontdiff
efi-stub.txt efi_stub: update documentation on dtb= parameter 2018-09-09 14:46:44 -06:00
eisa.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcc-plugins.txt
highuid.txt
hw_random.txt
hwspinlock.txt
index.rst docs: tidy up TOCs and refs to license-rules.rst 2018-08-31 16:50:50 -06:00
intel_txt.txt
Intel-IOMMU.txt
io_ordering.txt
io-mapping.txt
iostats.txt block: Track DISCARD statistics and output them in stat and diskstat 2018-07-18 08:44:22 -06:00
IPMI.txt
IRQ-affinity.txt
IRQ-domain.txt
IRQ.txt
irqflags-tracing.txt
isa.txt
isapnp.txt
kernel-per-CPU-kthreads.txt doc: Update removal of RCU-bh/sched update machinery 2018-08-30 10:59:48 -07:00
kobject.txt
kprobes.txt kprobes/Documentation: Fix various typos 2018-06-22 11:10:55 +02:00
kref.txt
ldm.txt
lockup-watchdogs.txt
logo.gif
logo.txt
lsm.txt
lzo.txt
mailbox.txt
Makefile
memory-barriers.txt locking/memory-barriers: Replace smp_cond_acquire() with smp_cond_load_acquire() 2018-10-02 10:28:05 +02:00
men-chameleon-bus.txt
nommu-mmap.txt Documentation: nommu-map: Fix duplicate word typo 2018-06-26 09:01:27 -06:00
ntb.txt
numastat.txt
padata.txt
parport-lowlevel.txt
percpu-rw-semaphore.txt
phy.txt
pi-futex.txt
pnp.txt
preempt-locking.txt Documentation: preempt-locking: Use better example 2018-10-12 11:35:47 -06:00
pwm.txt
rbtree.txt
remoteproc.txt
rfkill.txt rfkill: Fix several typos in documentation 2018-06-15 13:36:08 +02:00
robust-futex-ABI.txt
robust-futexes.txt
rpmsg.txt
rtc.txt
SAK.txt
sgi-ioc4.txt
siphash.txt
SM501.txt
smsc_ece1099.txt
speculation.txt
static-keys.txt
SubmittingPatches
svga.txt
switchtec.txt NTB: switchtec_ntb: Update switchtec documentation with prerequisites for NTB 2018-10-11 11:28:53 -05:00
sync_file.txt
tee.txt
this_cpu_ops.txt
unaligned-memory-access.txt
vfio-mediated-device.txt vfio/mdev: Check globally for duplicate devices 2018-06-08 10:24:27 -06:00
vfio.txt vfio: fix documentation 2018-05-08 09:16:41 -06:00
video-output.txt
xillybus.txt
xz.txt
zorro.txt