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39c60a0948
linux/drivers
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James Bottomley 39c60a0948 [SCSI] sd: fix array cache flushing bug causing performance problems 
Some arrays synchronize their full non volatile cache when the sd driver sends
a SYNCHRONIZE CACHE command.  Unfortunately, they can have Terrabytes of this
and we send a SYNCHRONIZE CACHE for every barrier if an array reports it has a
writeback cache.  This leads to massive slowdowns on journalled filesystems.

The fix is to allow userspace to turn off the writeback cache setting as a
temporary measure (i.e. without doing the MODE SELECT to write it back to the
device), so even though the device reported it has a writeback cache, the
user, knowing that the cache is non volatile and all they care about is
filesystem correctness, can turn that bit off in the kernel and avoid the
performance ruinous (and safety irrelevant) SYNCHRONIZE CACHE commands.

The way you do this is add a 'temporary' prefix when performing the usual
cache setting operations, so

echo temporary write through > /sys/class/scsi_disk/<disk>/cache_type

Reported-by: Ric Wheeler <rwheeler@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2013-05-02 16:15:54 -07:00
..
accessibility
acpi Power management and ACPI updates for 3.10-rc1 2013-04-30 15:21:02 -07:00
amba
ata 1) More ACPI fixes, cleanups 2013-04-30 16:13:36 -07:00
atm atm: he: use mdelay instead of large udelay constants 2013-04-29 13:26:48 -04:00
auxdisplay
base Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2013-05-01 13:20:04 -07:00
bcma
block aoe: replace kmalloc and then memcpy with kmemdup 2013-04-30 17:04:08 -07:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
bus
cdrom
char Merge branch 'akpm' (incoming from Andrew) 2013-04-30 17:37:43 -07:00
clk Power management and ACPI updates for 3.10-rc1 2013-04-30 15:21:02 -07:00
clocksource Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-04-30 08:15:40 -07:00
connector
cpufreq Merge branch 'pm-cpufreq' 2013-04-29 00:08:46 +02:00
cpuidle cpuidle: add maintainer entry 2013-04-26 22:30:25 +02:00
crypto Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-04-30 09:36:50 -07:00
dca
devfreq
dio
dma Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-04-22 20:32:51 -04:00
edac Merge branch 'linux_next' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-edac 2013-04-30 10:00:49 -07:00
eisa PCI changes for the v3.10 merge window: 2013-04-29 09:30:25 -07:00
extcon
firewire
firmware dmi_scan: refactor dmi_scan_machine(), {smbios,dmi}_present() 2013-04-30 17:04:04 -07:00
gpio These are the pinctrl changes for v3.10: 2013-04-29 09:40:35 -07:00
gpu Power management and ACPI updates for 3.10-rc1 2013-04-30 15:21:02 -07:00
hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2013-04-30 09:37:55 -07:00
hsi
hv Merge branch 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-04-30 08:41:21 -07:00
hwmon Highlights: 2013-04-30 15:15:24 -07:00
hwspinlock
i2c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-04-30 09:36:50 -07:00
ide
idle Merge branch 'pm-cpuidle' 2013-04-28 01:54:49 +02:00
iio
infiniband Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2013-05-01 13:20:04 -07:00
iommu Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-04-30 08:40:35 -07:00
ipack
irqchip Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-04-30 09:36:50 -07:00
isdn Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
leds
lguest lguest: rename random32() to prandom_u32() 2013-04-29 18:28:43 -07:00
macintosh
mailbox
md MD: ignore discard request for hard disks of hybid raid1/raid10 array 2013-04-30 14:49:36 +10:00
media Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
memory
memstick drivers/memstick/host/r592.c: make r592_pm_ops static 2013-04-30 17:04:08 -07:00
message i2o: check copy_from_user() size parameter 2013-04-30 17:04:04 -07:00
mfd Highlights: 2013-04-30 15:15:24 -07:00
misc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-04-30 09:36:50 -07:00
mmc mmc: rename random32() to prandom_u32() 2013-04-29 18:28:42 -07:00
mtd
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
nfc
ntb
nubus
of Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
oprofile
parisc
parport
pci Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
pcmcia
pinctrl pinctrl: move subsystem mutex to pinctrl_dev struct 2013-04-26 17:01:35 +02:00
platform Merge branch 'acpica' 2013-04-28 01:53:50 +02:00
pnp Merge branch 'pnp' 2013-04-28 01:54:41 +02:00
power Highlights: 2013-04-30 15:15:24 -07:00
pps pps: pps_kc_hardpps_lock can be static 2013-04-30 17:04:08 -07:00
ps3
ptp
pwm
rapidio
regulator Merge remote-tracking branch 'regulator/topic/wm8994' into v3.9-rc8 2013-04-28 02:13:50 +01:00
remoteproc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-04-30 09:36:50 -07:00
rpmsg drivers/rpmsg/virtio_rpmsg_bus.c: fix error return code in rpmsg_probe() 2013-04-29 18:28:13 -07:00
rtc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-04-30 09:36:50 -07:00
s390 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
sbus
scsi [SCSI] sd: fix array cache flushing bug causing performance problems 2013-05-02 16:15:54 -07:00
sfi
sh
sn
spi spi: Updates for v3.10 2013-04-29 16:38:41 -07:00
ssb ssb: implement ssb spuravoid for chipid BCM43222 2013-04-26 08:42:22 -04:00
ssbi
staging Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
target tcm_fc: Check for aborted sequence 2013-04-25 01:05:28 -07:00
tc
thermal
tty Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2013-05-01 13:20:04 -07:00
uio
usb Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2013-05-01 13:20:04 -07:00
uwb uwb: rename random32() to prandom_u32() 2013-04-29 18:28:43 -07:00
vfio PCI changes for the v3.10 merge window: 2013-04-29 09:30:25 -07:00
vhost Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
video Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-04-30 09:36:50 -07:00
virt
virtio
vlynq
vme
w1 drivers/w1/slaves/w1_ds2760.c: fix the error handling in w1_ds2760_add_slave() 2013-04-30 17:04:08 -07:00
watchdog
xen zcache/tmem: Better error checking on frontswap_register_ops return value. 2013-04-30 17:04:01 -07:00
zorro
Kconfig kconfig menu: move Virtualization drivers near other virtualization options 2013-04-30 17:04:09 -07:00
Makefile USB patches for 3.10-rc1 2013-04-29 12:19:23 -07:00