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Dave Hansen 5509a5d27b drop_caches: add some documentation and info message 
There is plenty of anecdotal evidence and a load of blog posts
suggesting that using "drop_caches" periodically keeps your system
running in "tip top shape".  Perhaps adding some kernel documentation
will increase the amount of accurate data on its use.

If we are not shrinking caches effectively, then we have real bugs.
Using drop_caches will simply mask the bugs and make them harder to
find, but certainly does not fix them, nor is it an appropriate
"workaround" to limit the size of the caches.  On the contrary, there
have been bug reports on issues that turned out to be misguided use of
cache dropping.

Dropping caches is a very drastic and disruptive operation that is good
for debugging and running tests, but if it creates bug reports from
production use, kernel developers should be aware of its use.

Add a bit more documentation about it, a syslog message to track down
abusers, and vmstat drop counters to help analyze problem reports.

[akpm@linux-foundation.org: checkpatch fixes]
[hannes@cmpxchg.org: add runtime suppression control]
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-03 16:21:04 -07:00
..
ABI Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-04-02 20:53:45 -07:00
accounting Documentation/accounting/getdelays.c: avoid strncpy in accounting tool 2013-07-03 16:08:06 -07:00
acpi ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
aoe aoe: remove do-nothing NAME="%k" term from example udev rules 2013-09-11 15:59:28 -07:00
arm Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
arm64 arm64: Extend the PCI I/O space to 16MB 2014-02-26 11:16:27 +00:00
auxdisplay
backlight backlight: lp855x_bl: support new LP8555 device 2013-11-13 12:09:14 +09:00
blackfin Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
block Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
blockdev drbd: Describe the future high-level structure of DRBD 2014-02-17 16:27:48 +01:00
bus-devices
cdrom
cgroups Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2014-01-31 09:31:14 -08:00
connector connector: add portid to unicast in addition to broadcasting 2014-02-07 15:40:17 -08:00
console
cpu-freq cpufreq: Add stop CPU callback to cpufreq_driver interface 2014-03-20 03:50:12 +01:00
cpuidle cpuidle: remove cpuidle_unregister_governor() 2013-10-30 01:21:24 +01:00
cris
crypto drivers/dma: remove unused support for MEMSET operations 2013-07-03 16:07:42 -07:00
development-process Documentation: development-process: Update -mm and -next URLs 2013-07-25 12:37:24 +02:00
device-mapper dm thin: fix Documentation for held metadata root feature 2014-03-06 14:23:35 -05:00
devicetree Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-04-02 20:53:45 -07:00
DocBook Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-04-02 20:53:45 -07:00
driver-model Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-01-22 21:21:55 -08:00
dvb [media] update Michael Krufky's email address 2014-02-04 06:34:21 -02:00
early-userspace Documentation: remove reference to 2.7 kernel in early-userspace 2013-08-20 12:47:28 +02:00
EDID
extcon extcon: fix switch class porting guide (Documentation) 2014-01-07 11:54:28 +09:00
fault-injection
fb Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
filesystems mm + fs: store shadow entries in page cache 2014-04-03 16:21:01 -07:00
firmware_class
fmc FMC: make eeprom attribute writable 2014-02-28 15:12:08 -08:00
frv
gpio gpiolib: return -ENOENT if no GPIO mapping exists 2013-12-12 19:33:59 +01:00
hid HID: uhid: Add UHID_CREATE2 + UHID_INPUT2 2014-04-01 18:27:33 +02:00
hwmon hwmon: (pmbus/ltc2978) Add support for LTM4676 2014-03-19 18:59:40 -07:00
i2c Documentation: i2c: mention ACPI method for instantiating devices 2014-02-15 19:46:34 +01:00
i2o
ia64
ide Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
infiniband
input doc: fix double words 2014-03-21 13:16:58 +01:00
ioctl s390/hypfs: add interface for diagnose 0x304 2014-01-24 09:40:59 +01:00
isdn
ja_JP Documentation: ja_JP: Update broken link to tpp 2013-12-10 23:09:08 -08:00
kbuild Documentation/kbuild/kconfig.txt: 'make listnewconfig' replaces: yes "" | make oldconfig 2013-10-08 23:51:50 +02:00
kdump Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-07-04 11:40:58 -07:00
ko_KR Documentation: HOWTO: Updates on subsystem trees, patchwork, -next (vs. -mm) in ko_KR 2014-01-08 15:32:51 -08:00
laptops Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
leds Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
m68k Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
make
memory-devices
metag
mic misc: mic: Fix endianness issues. 2013-11-27 11:03:38 -08:00
mips
misc-devices Merge branch 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging 2014-01-29 18:56:27 -08:00
mmc
mn10300
mtd mtd: nand: pxa3xx: Add documentation about the controller 2014-01-03 11:22:09 -08:00
namespaces
netlabel
networking Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-04-02 20:53:45 -07:00
nfc
parisc parisc: document the shadow registers 2013-07-09 22:09:19 +02:00
PCI Merge branch 'pci/dead-code' into next 2014-02-20 14:32:34 -07:00
pcmcia
phy phy: Add new Exynos USB 2.0 PHY driver 2014-03-08 12:39:44 +05:30
power Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-04-02 16:23:38 -07:00
powerpc powerpc: Update the 00-Index in Documentation/powerpc 2013-08-27 14:44:27 +10:00
pps USB: serial: invoke dcd_change ldisc's handler. 2013-09-26 09:45:40 -07:00
prctl
pti
ptp ptp: Fix compiler warnings in the testptp utility 2014-03-27 14:51:47 -04:00
rapidio doc: Fix typo in doucmentations 2013-07-25 12:34:15 +02:00
RCU documentation: Fix some inconsistencies in RTFP.txt 2014-02-17 14:56:10 -08:00
s390 Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
scheduler Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
scsi [SCSI] megaraid_sas: Version and Changelog update 2014-03-15 10:19:21 -07:00
security doc: fix double words 2014-03-21 13:16:58 +01:00
serial Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
sh
sound x86, platforms: Remove SGI Visual Workstation 2014-02-27 08:07:39 -08:00
spi Merge remote-tracking branches 'spi/topic/s3c64xx', 'spi/topic/sc18is602', 'spi/topic/sh-hspi', 'spi/topic/sh-msiof', 'spi/topic/sh-sci', 'spi/topic/sirf' and 'spi/topic/spidev' into spi-next 2014-03-30 00:51:34 +00:00
sysctl drop_caches: add some documentation and info message 2014-04-03 16:21:04 -07:00
target target: Remove TF_CIT_TMPL macro 2013-10-16 13:35:02 -07:00
thermal thermal: thermal_core: allow binding with limits on bind_params 2013-09-03 09:10:24 -04:00
timers Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
tpm drivers/tpm: add xen tpmfront interface 2013-08-09 10:57:06 -04:00
trace Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-04-02 16:23:38 -07:00
usb doc: fix double words 2014-03-21 13:16:58 +01:00
vDSO
video4linux [media] sn9c102: prepare for removal by moving it to staging 2013-12-20 13:41:36 -02:00
virtual Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-04-02 16:23:38 -07:00
vm doc: fix double words 2014-03-21 13:16:58 +01:00
w1 Merge 3.14-rc3 into char-misc-next 2014-02-18 08:09:40 -08:00
watchdog watchdog: it87_wdt: Work around non-working CIR interrupts 2014-03-31 13:33:55 +02:00
wimax
x86 x86, boot: Correct max ramdisk size name 2014-03-13 15:32:42 -07:00
xtensa xtensa: remap io area defined in device tree 2014-01-15 00:25:14 +04:00
zh_CN Documentation:Update Documentation/zh_CN/arm64/memory.txt 2014-02-07 15:24:31 -08:00
.gitignore
00-INDEX Merge branch 'x86-nuke-platforms-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-02 13:15:58 -07:00
applying-patches.txt
assoc_array.txt KEYS: Fix multiple key add into associative array 2013-12-02 11:24:18 +00:00
atomic_ops.txt
bad_memory.txt
basic_profiling.txt
bcache.txt Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-07-04 11:40:58 -07:00
binfmt_misc.txt
braille-console.txt
bt8xxgpio.txt
btmrvl.txt
BUG-HUNTING
bus-virt-phys-mapping.txt
cachetlb.txt Documentation: fix typo and update version in cachetlb.txt 2013-08-20 12:46:52 +02:00
Changes remove obsolete references to powertweak 2013-11-27 20:34:32 -08:00
circular-buffers.txt documentation: Update circular buffer for load-acquire/store-release 2013-12-03 10:08:57 -08:00
clk.txt clk: Add set_rate_and_parent() op 2014-01-16 12:00:57 -08:00
coccinelle.txt Coccinelle: Update information about the minimal version required 2013-07-03 22:58:20 +02:00
CodingStyle Documentation/CodingStyle: allow multiple return statements per function 2013-07-03 16:08:01 -07:00
cpu-hotplug.txt Documentation/cpu-hotplug.txt: fix a typo in example code 2014-01-23 16:37:01 -08:00
cpu-load.txt
cputopology.txt doc: Documentation/cputopology.txt fix typo 2013-09-04 12:59:47 +02:00
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt firewire: Enable remote DMA above 4 GB 2014-01-20 01:11:13 +01:00
dell_rbu.txt
devices.txt Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-04-02 20:53:45 -07:00
digsig.txt
DMA-API-HOWTO.txt DMA-API: provide a helper to set both DMA and coherent DMA masks 2013-09-17 15:32:37 +01:00
DMA-API.txt DMA-API: provide a helper to set both DMA and coherent DMA masks 2013-09-17 15:32:37 +01:00
DMA-attributes.txt doc: Documentation/DMA-attributes.txt fix typo 2013-10-14 15:50:53 +02:00
dma-buf-sharing.txt dma-buf: Expose buffer size to userspace (v2) 2013-09-10 11:36:45 +05:30
DMA-ISA-LPC.txt
dmaengine.txt
dmatest.txt dmatest: add a 'wait' parameter 2013-11-14 11:04:40 -08:00
dontdiff
dynamic-debug-howto.txt dynamic-debug-howto.txt: update since new wildcard support 2014-01-23 16:36:55 -08:00
edac.txt
efi-stub.txt doc: Fix trivial spelling mistake in efi-stub.txt 2013-12-19 15:09:14 +01:00
eisa.txt
email-clients.txt doc: fix some typos 2013-12-02 14:48:28 +01:00
flexible-arrays.txt
futex-requeue-pi.txt doc: fix double words 2014-03-21 13:16:58 +01:00
gcov.txt gcov: compile specific gcov implementation based on gcc version 2013-11-13 12:09:34 +09:00
highuid.txt
HOWTO Documentation: HOWTO: Update broken links to tpp 2013-12-10 23:09:08 -08:00
hw_random.txt
hwspinlock.txt doc: documentation/hwspinlock.txt fix typo 2013-08-27 10:46:02 +02:00
init.txt
initrd.txt
intel_txt.txt
Intel-IOMMU.txt
io_ordering.txt
io-mapping.txt doc: fix some typos 2013-12-02 14:48:28 +01:00
iostats.txt
IPMI.txt
IRQ-affinity.txt doc: fix a typo about irq affinity 2013-08-20 12:59:18 +02:00
IRQ-domain.txt doc: fix some typos 2013-12-02 14:48:28 +01:00
IRQ.txt
irqflags-tracing.txt
isapnp.txt
java.txt
kernel-doc-nano-HOWTO.txt
kernel-docs.txt
kernel-parameters.txt More ACPI and power management updates for 3.15-rc1 2014-04-02 14:10:21 -07:00
kernel-per-CPU-kthreads.txt Documentation/kernel-per-CPU-kthreads.txt: Workqueue affinity 2014-02-17 14:56:08 -08:00
kmemcheck.txt doc: fix double words 2014-03-21 13:16:58 +01:00
kmemleak.txt kmemleak: allow freeing internal objects after kmemleak was disabled 2014-04-03 16:20:50 -07:00
kobject.txt kobject: remove kset from sysfs immediately in kset_unregister() 2013-12-07 21:20:11 -08:00
kprobes.txt
kref.txt
ldm.txt
local_ops.txt
lockdep-design.txt
lockstat.txt lockstat: Report avg wait and hold times 2013-10-09 08:19:08 +02:00
lockup-watchdogs.txt
logo.gif
logo.txt
magic-number.txt
Makefile
ManagementStyle
md.txt doc: fix some typos in documentations 2013-12-02 14:45:19 +01:00
media-framework.txt Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2013-07-13 12:09:57 -07:00
memory-barriers.txt Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2014-04-02 16:23:38 -07:00
memory-hotplug.txt Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-09-06 09:36:28 -07:00
module-signing.txt doc: Insert MODULE_ in module-signing macros 2014-02-20 14:55:04 +01:00
mono.txt
mutex-design.txt locking/doc: Update references to kernel/mutex.c 2013-11-11 12:41:33 +01:00
nommu-mmap.txt
numastat.txt
oops-tracing.txt
padata.txt
parport-lowlevel.txt
parport.txt
percpu-rw-semaphore.txt
phy.txt drivers: phy: Add support for optional phys 2014-02-05 05:48:43 +00:00
pi-futex.txt
pinctrl.txt pinctrl: Fix some typos and grammar issues in the documentation 2014-01-15 13:59:50 +01:00
pnp.txt
preempt-locking.txt
printk-formats.txt vsprintf: add %pad extension for dma_addr_t use 2014-01-23 16:36:56 -08:00
pwm.txt Documentation/pwm: Fix trivial typos 2013-10-24 10:51:33 +02:00
ramoops.txt
rbtree.txt
remoteproc.txt
rfkill.txt doc: fix some typos in documentations 2013-12-02 14:45:19 +01:00
robust-futex-ABI.txt Documentation/robust-futex-API: Count properly to 4 2013-11-30 14:08:28 +01:00
robust-futexes.txt
rpmsg.txt
rt-mutex-design.txt doc: fix some typos in documentations 2013-12-02 14:45:19 +01:00
rt-mutex.txt
rtc.txt rtc: add ability to push out an existing wakealarm using sysfs 2013-07-03 16:07:54 -07:00
SAK.txt
SecurityBugs
serial-console.txt
sgi-ioc4.txt
SM501.txt
smsc_ece1099.txt
sparse.txt
spinlocks.txt sched: Rename sched.c as sched/core.c in comments and Documentation 2013-06-19 12:58:42 +02:00
stable_api_nonsense.txt
stable_kernel_rules.txt
static-keys.txt doc: fix some typos in documentations 2013-12-02 14:45:19 +01:00
SubmitChecklist
SubmittingDrivers
SubmittingPatches Documentation/SubmittingPatches: Request summaries for commit references 2013-08-20 12:58:15 +02:00
svga.txt
sysfs-rules.txt doc: Fix typo in doucmentations 2013-07-25 12:34:15 +02:00
sysrq.txt sysrq: Allow magic SysRq key functions to be disabled through Kconfig 2013-10-16 13:01:44 -07:00
this_cpu_ops.txt
unaligned-memory-access.txt ether_addr_equal: Optimize implementation, remove unused compare_ether_addr 2013-12-06 16:37:43 -05:00
unicode.txt
unshare.txt
vfio.txt vfio: fix documentation 2013-09-05 16:36:21 -06:00
VGA-softcursor.txt
vgaarbiter.txt
video-output.txt
vme_api.txt VME: Rename vme_slot_get to avoid confusion with reference counting 2013-12-03 11:15:58 -08:00
volatile-considered-harmful.txt
workqueue.txt workqueue: Correct/Drop references to gcwq in Documentation 2013-08-21 10:32:09 -04:00
ww-mutex-design.txt mutex: Add support for wound/wait style locks 2013-06-26 12:10:56 +02:00
xz.txt
zorro.txt zorro/UAPI: Disintegrate include/linux/zorro*.h 2013-11-26 11:09:08 +01:00