Claudio Imbrenda e86c59b1b1 mm/ksm: improve deduplication of zero pages with colouring ... Some architectures have a set of zero pages (coloured zero pages) instead of only one zero page, in order to improve the cache performance. In those cases, the kernel samepage merger (KSM) would merge all the allocated pages that happen to be filled with zeroes to the same deduplicated page, thus losing all the advantages of coloured zero pages. This behaviour is noticeable when a process accesses large arrays of allocated pages containing zeroes. A test I conducted on s390 shows that there is a speed penalty when KSM merges such pages, compared to not merging them or using actual zero pages from the start without breaking the COW. This patch fixes this behaviour. When coloured zero pages are present, the checksum of a zero page is calculated during initialisation, and compared with the checksum of the current canditate during merging. In case of a match, the normal merging routine is used to merge the page with the correct coloured zero page, which ensures the candidate page is checked to be equal to the target zero page. A sysfs entry is also added to toggle this behaviour, since it can potentially introduce performance regressions, especially on architectures without coloured zero pages. The default value is disabled, for backwards compatibility. With this patch, the performance with KSM is the same as with non COW-broken actual zero pages, which is also the same as without KSM. [akpm@linux-foundation.org: make zero_checksum and ksm_use_zero_pages __read_mostly, per Andrea] [imbrenda@linux.vnet.ibm.com: documentation for coloured zero pages deduplication] Link: http://lkml.kernel.org/r/1484927522-1964-1-git-send-email-imbrenda@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1484850953-23941-1-git-send-email-imbrenda@linux.vnet.ibm.com Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2017-02-24 17:46:53 -08:00
..
ABI	First set of updates for 4.11 kernel merge window	2017-02-23 08:27:57 -08:00
accounting	tools: move accounting tool from Documentation	2016-09-23 13:07:15 -06:00
acpi	ACPI / button: Remove lid_init_state=method mode	2017-01-31 17:20:45 +01:00
admin-guide	Merge branch 'akpm' (patches from Andrew)	2017-02-22 19:29:24 -08:00
aoe
arm	arm: sunxi: add support for V3s SoC	2017-01-20 21:31:34 +01:00
arm64	arm64: Work around Falkor erratum 1003	2017-02-10 11:22:12 +00:00
auxdisplay	samples: move auxdisplay example code from Documentation	2016-09-23 11:52:32 -06:00
backlight
blackfin	samples: move blackfin gptimers-example from Documentation	2016-10-10 07:12:02 -06:00
block	A slightly quieter cycle for documentation this time around.	2017-02-22 18:51:29 -08:00
blockdev	zram: remove obsolete sysfs attrs	2017-02-22 16:41:30 -08:00
bus-devices
cdrom	cdrom: Make device operations read-only	2017-02-14 08:29:56 -07:00
cgroup-v1	Documentation: cpuset: Fix 'cpuset.tasks' -> 'tasks'	2017-01-13 11:04:45 -07:00
cma
connector	samples: connector: from Documentation to samples directory	2016-04-28 07:47:35 -06:00
console
core-api	Documentation: Update CPU hotplug and move it to core-api	2017-01-13 10:32:32 -07:00
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	dmaengine: Documentation: Fix typo in pxa_dma.txt	2016-11-14 08:14:24 +05:30
doc-guide	docs-rst: parse-headers.pl: cleanup the documentation	2016-11-30 17:08:09 -07:00
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	extcon: int3496: Add Intel INT3496 ACPI device extcon driver	2017-01-09 10:04:11 +09:00
fault-injection
fb	Documentation: fb: fix spelling mistakes	2016-05-10 12:05:27 +03:00
features	2nd round of ARC udpates for 4.10rc1	2016-12-23 10:22:47 -08:00
filesystems	rxrpc: Change module filename to rxrpc.ko	2017-02-17 15:09:19 -05:00
firmware_class	firmware: revamp firmware documentation	2017-01-11 09:42:59 +01:00
fmc
fpga	fpga: Add scatterlist based programming	2017-02-10 15:20:44 +01:00
frv	docs: fix locations of several documents that got moved	2016-10-24 08:12:35 -02:00
gpio	gpio: random documentation update	2017-01-31 15:43:05 +01:00
gpu	Less anger inducing pull request for 4.11	2017-02-23 18:58:18 -08:00
hid	Documentation: HID: Intel ISH HID document	2016-08-17 11:13:07 +02:00
hwmon	A slightly quieter cycle for documentation this time around.	2017-02-22 18:51:29 -08:00
i2c	Merge branch 'i2c/for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux	2016-12-15 12:56:35 -08:00
ia64	selftests: move ia64 tests from Documentation/ia64	2016-09-20 09:58:12 -06:00
ide
iio	iio: Documentation: Correct the path used to create triggers.	2016-10-01 00:49:58 -06:00
infiniband	IB/hfi1: Document new sysfs entries for hfi1 driver	2016-10-02 08:42:19 -04:00
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	docs: fix locations of several documents that got moved	2016-10-24 08:12:35 -02:00
kbuild	Kconfig: Introduce the "imply" keyword	2016-11-16 09:26:33 +01:00
kdump	Documentation: kdump: Add description of enable multi-cpus support	2016-09-20 18:02:54 -06:00
laptops	platform/x86: thinkpad_acpi: Add support for X1 Yoga (2016) Tablet Mode	2016-12-13 09:29:06 -08:00
leds	leds: class: Add new optional brightness_hw_changed attribute	2017-01-29 19:59:42 +01:00
livepatch	A slightly quieter cycle for documentation this time around.	2017-02-22 18:51:29 -08:00
locking	locking/ww_mutex/Documentation: Update the design document	2017-01-14 11:14:55 +01:00
m68k	docs: fix locations of several documents that got moved	2016-10-24 08:12:35 -02:00
media	A slightly quieter cycle for documentation this time around.	2017-02-22 18:51:29 -08:00
memory-devices
metag
mic	samples: move mic/mpssd example code from Documentation	2016-09-20 12:38:48 -06:00
mips
misc-devices	samples: move misc-devices/mei example code from Documentation	2016-09-23 11:51:43 -06:00
mmc	mmc: core: Extend sysfs with DSR register	2016-07-25 10:34:51 +02:00
mn10300
mtd	spi-nor: Add support for Intel SPI serial flash controller	2017-01-03 17:33:36 +00:00
namespaces
netlabel
networking	A slightly quieter cycle for documentation this time around.	2017-02-22 18:51:29 -08:00
nfc
nios2
nvdimm	libnvdimm, btt: update the usage section in Documentation	2016-06-17 16:23:23 -07:00
nvmem
parisc
PCI	Merge branch 'pci/msi' into next	2017-02-15 11:56:10 -06:00
pcmcia	tools: move pcmcia crc32hash tool from Documentation	2016-09-23 13:07:27 -06:00
perf	perf: add qcom l2 cache perf events driver	2017-02-08 19:32:24 +00:00
phy
platform
power	A slightly quieter cycle for documentation this time around.	2017-02-22 18:51:29 -08:00
powerpc	powerpc updates for 4.9	2016-10-07 20:19:31 -07:00
pps	Doc: clarify source of jitter in USB1.1, and USB2.0	2017-01-04 14:40:52 -07:00
prctl	selftests: move prctl tests from Documentation/prctl	2016-09-20 09:09:09 -06:00
process	Doc: Correct typo, "Introdution" => "Introduction"	2016-12-01 10:44:08 -07:00
pti
ptp	selftests: move ptp tests from Documentation/ptp	2016-09-20 09:54:38 -06:00
rapidio	rapidio/documentation/mport_cdev: add missing parameter description	2016-09-01 17:52:02 -07:00
RCU	Merge branches 'doc.2017.01.15b', 'dyntick.2017.01.23a', 'fixes.2017.01.23a', 'srcu.2017.01.25a' and 'torture.2017.01.15b' into HEAD	2017-01-25 12:56:05 -08:00
s390	s390/Documentation: improve sort command for trace buffer	2016-06-13 15:58:23 +02:00
scheduler	sched/Documentation/sched-rt-group: Fix incorrect example	2017-01-22 10:34:17 +01:00
scsi	Merge branch 'misc' into for-linus	2016-12-22 12:32:33 -08:00
security	This renames the (now inaccurate) CONFIG_DEBUG_RODATA and related config	2017-02-21 17:56:45 -08:00
serial	Documentation: rs485: Do not define manually the ioctl	2016-08-18 11:08:33 -06:00
sh
sound	ALSA: Documentation about HDA DP MST pin init and connection	2017-01-12 10:06:47 +01:00
sphinx	docs: sphinx-extensions: make rstFlatTable work with docutils 0.13	2016-12-18 13:30:29 -07:00
sphinx-static	This is the documentation update pull for the 4.9 merge window.	2016-10-04 13:54:07 -07:00
spi	spi: spi-ep93xx: simplify GPIO chip selects	2017-02-16 20:10:26 +00:00
sysctl	bpf: make jited programs visible in traces	2017-02-17 13:40:05 -05:00
target	target: make close_session optional	2016-05-10 01:19:26 -07:00
thermal	Documentation: fix spelling mistakes of "Celcius" -- > "Celsius"	2017-01-04 14:36:17 -07:00
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/ksm: improve deduplication of zero pages with colouring	2017-02-24 17:46:53 -08:00
w1	w1: add ability to set (SRAM) and store (EEPROM) configuration for temp sensors like DS18B20	2016-05-01 14:37:49 -07:00
watchdog	docs: fix locations of several documents that got moved	2016-10-24 08:12:35 -02:00
wimax
x86	efi: Get and store the secure boot status	2017-02-07 10:42:10 +01:00
xtensa	xtensa: cleanup MMU setup and kernel layout macros	2016-07-24 06:33:58 +03:00
.gitignore	Add .pyc files to .gitignore	2016-06-30 13:07:33 -06:00
00-INDEX	edac: adjust docs location at MAINTAINERS and 00-INDEX	2016-12-15 08:57:16 -02:00
bcache.txt	bcache: documentation formatting, edited for clarity, stripe alignment notes	2016-06-23 07:58:38 -06:00
bt8xxgpio.txt
btmrvl.txt
bus-virt-phys-mapping.txt
cachetlb.txt
cgroup-v2.txt
Changes	docs: add back 'Documentation/Changes' file (as symlink)	2016-12-14 16:30:12 -08:00
circular-buffers.txt	Documentation: circular-buffers: use READ_ONCE()	2016-11-16 16:17:45 -07:00
clk.txt	Documentation: clk: update file names containing referenced structures	2016-08-14 12:12:36 -06:00
CodingStyle	doc: re-add CodingStyle and SubmittingPatches	2016-10-24 08:12:35 -02:00
conf.py	docs: Remove the copyright year from conf.py	2017-02-06 11:52:19 -07:00
cpu-load.txt
cputopology.txt	topology/sysfs: provide drawer id and siblings attributes	2016-06-13 15:58:27 +02:00
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt
digsig.txt
DMA-API-HOWTO.txt	Documentation: DMA-API-HOWTO: Fix a typo	2016-09-20 17:58:46 -06:00
DMA-API.txt	dma-mapping: add dma_{map,unmap}_resource	2016-09-26 22:16:41 +05:30
DMA-attributes.txt	common: DMA-mapping: add DMA_ATTR_PRIVILEGED attribute	2017-01-19 15:56:19 +00:00
DMA-ISA-LPC.txt	Documentation: DMA-ISA-LPC.txt	2017-02-12 15:20:07 -07:00
docutils.conf	doc-rst: add docutils config file	2016-08-14 11:52:40 -06:00
dontdiff	Documentation: dontdiff: Update with additional entries	2017-01-26 15:08:06 -07:00
efi-stub.txt
eisa.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcc-plugins.txt	GCC plugin infrastructure	2016-06-07 22:57:10 +02:00
highuid.txt
hw_random.txt
hwspinlock.txt
index.rst	docs/zh_CN: Add coding-style into docs build system	2017-01-26 15:30:34 -07:00
intel_txt.txt
Intel-IOMMU.txt
io_ordering.txt
io-mapping.txt
iostats.txt
IPMI.txt	ipmi: Update documentation	2016-11-07 12:16:06 -06:00
IRQ-affinity.txt
IRQ-domain.txt
IRQ.txt
irqflags-tracing.txt
isa.txt	Documentation: Add ISA bus driver documentation	2016-05-02 09:32:04 -07:00
isapnp.txt
kernel-doc-nano-HOWTO.txt	docs-rst: doc-guide: split the kernel-documentation.rst contents	2016-11-19 10:22:04 -07:00
kernel-per-CPU-kthreads.txt	docs: fix locations of several documents that got moved	2016-10-24 08:12:35 -02:00
kobject.txt
kprobes.txt	Documentation: kprobes: Document jprobes stack copying limitations	2016-08-15 10:19:11 -06:00
kref.txt
kselftest.txt	Doc: update kselftest.txt with details on how to run tests after install	2016-11-07 18:04:18 -07:00
ldm.txt
lockup-watchdogs.txt	docs: fix locations of several documents that got moved	2016-10-24 08:12:35 -02:00
logo.gif
logo.txt
lzo.txt	Documentation: lzo: fix spelling mistakes	2016-04-28 07:23:11 -06:00
mailbox.txt
Makefile	samples: move blackfin gptimers-example from Documentation	2016-10-10 07:12:02 -06:00
Makefile.sphinx	Add a target to check broken external links in the Documentation	2017-02-15 15:22:47 -07:00
md-cluster.txt	md-cluster: change array_sectors and update size are not supported	2016-05-04 12:39:35 -07:00
memory-barriers.txt	doc: Update control-dependencies section of memory-barriers.txt	2017-01-14 21:29:15 -08:00
memory-hotplug.txt	docs: fix locations of several documents that got moved	2016-10-24 08:12:35 -02:00
men-chameleon-bus.txt
nommu-mmap.txt
ntb.txt
numastat.txt
padata.txt
parport-lowlevel.txt
percpu-rw-semaphore.txt
phy.txt	phy: core: Allow children node to be overridden	2016-04-29 16:39:39 +02:00
pi-futex.txt
pinctrl.txt	pinctrl: core: Fix regression caused by delayed work for hogs	2017-01-13 16:25:17 +01:00
pnp.txt
preempt-locking.txt
printk-formats.txt
pwm.txt	pwm: Update documentation	2016-05-17 14:48:04 +02:00
rbtree.txt
remoteproc.txt	remoteproc: Split driver and consumer dereferencing	2016-10-02 22:50:21 -07:00
rfkill.txt	docs: fix locations of several documents that got moved	2016-10-24 08:12:35 -02:00
robust-futex-ABI.txt
robust-futexes.txt	Documentation: robust-futexes: fix spelling mistakes	2016-04-28 07:26:41 -06:00
rpmsg.txt	rpmsg: use module_rpmsg_driver in existing drivers and examples	2016-05-06 11:09:01 -07:00
rtc.txt
SAK.txt
sgi-ioc4.txt
siphash.txt	siphash: implement HalfSipHash1-3 for hash tables	2017-01-09 13:58:57 -05:00
SM501.txt
smsc_ece1099.txt
static-keys.txt	jump_labels: Allow array initialisers	2016-09-07 09:41:11 +01:00
SubmittingPatches	doc: re-add CodingStyle and SubmittingPatches	2016-10-24 08:12:35 -02:00
svga.txt
sync_file.txt	dma-buf: Rename struct fence to dma_fence	2016-10-25 14:40:39 +02:00
this_cpu_ops.txt
unaligned-memory-access.txt	Documentation/unaligned-memory-access.txt: fix incorrect comparison operator	2016-12-27 13:08:42 -07:00
unshare.txt
vfio-mediated-device.txt	vfio-mdev: Make mdev_parent private	2016-12-30 08:13:41 -07:00
vfio.txt
video-output.txt
xillybus.txt	Documentation: xillybus: fix spelling mistake	2016-04-28 07:44:54 -06:00
xz.txt
zorro.txt