tmp_suning_uos_patched/drivers
Mustafa Mesanovic 2991520200 dm stripe: implement merge method
Implement a merge function in the striped target.

When the striped target's underlying devices provide a merge_bvec_fn
(like all DM devices do via dm_merge_bvec) it is important to call down
to them when building a biovec that doesn't span a stripe boundary.

Without the merge method, a striped DM device stacked on DM devices
causes bios with a single page to be submitted which results
in unnecessary overhead that hurts performance.

This change really helps filesystems (e.g. XFS and now ext4) which take
care to assemble larger bios.  By implementing stripe_merge(), DM and the
stripe target no longer undermine the filesystem's work by only allowing
a single page per bio.  Buffered IO sees the biggest improvement
(particularly uncached reads, buffered writes to a lesser degree).  This
is especially so for more capable "enterprise" storage LUNs.

The performance improvement has been measured to be ~12-35% -- when a
reasonable chunk_size is used (e.g. 64K) in conjunction with a stripe
count that is a power of 2.

In contrast, the performance penalty is ~5-7% for the pathological worst
case stripe configuration (small chunk_size with a stripe count that is
not a power of 2).  The reason for this is that stripe_map_sector() is
now called once for every call to dm_merge_bvec().  stripe_map_sector()
will use slower division if stripe count isn't a power of 2.

Signed-off-by: Mustafa Mesanovic <mume@linux.vnet.ibm.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-03-24 13:54:35 +00:00
..
accessibility
acpi acpi: tie ACPI backlight devices to PCI devices if possible 2011-03-22 17:44:00 -07:00
amba
ata Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2011-03-18 06:31:43 -07:00
atm Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-03-18 10:37:40 -07:00
auxdisplay
base
block Merge git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client 2011-03-22 16:25:25 -07:00
bluetooth Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-03-18 10:37:40 -07:00
cdrom
char Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-03-20 18:14:55 -07:00
clk
clocksource
connector
cpufreq
cpuidle
crypto
dca drivers/dca/dca-core.c: use list_move() instead of list_del()/list_add() combination 2011-03-22 17:44:12 -07:00
dio
dma Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx 2011-03-22 17:53:13 -07:00
edac Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-03-18 10:37:40 -07:00
eisa
firewire Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2011-03-21 10:05:22 -07:00
firmware sigma-firmware: loader for Analog Devices' SigmaStudio 2011-03-22 17:44:15 -07:00
gpio Merge branch 'spi/next' of git://git.secretlab.ca/git/linux-2.6 2011-03-18 10:56:02 -07:00
gpu nouveau: change the backlight parent device to the connector, not the PCI dev 2011-03-22 17:43:59 -07:00
hid backlight: add backlight type 2011-03-22 17:43:59 -07:00
hwmon hwmon: (ads1015) Make gain and datarate configurable 2011-03-21 17:59:37 +01:00
hwspinlock
i2c Merge branch 'for-linus/2639/i2c-2' of git://git.fluff.org/bjdooks/linux 2011-03-22 10:05:27 -07:00
ide
idle
ieee802154
infiniband Merge branch 'kvm-updates/2.6.39' of git://git.kernel.org/pub/scm/virt/kvm/kvm 2011-03-17 18:40:35 -07:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2011-03-19 22:27:06 -07:00
isdn Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-03-20 18:14:55 -07:00
leds drivers/leds/leds-lp5523.c: world-writable engine* sysfs files 2011-03-22 17:43:59 -07:00
lguest
macintosh backlight: add backlight type 2011-03-22 17:43:59 -07:00
mca
md dm stripe: implement merge method 2011-03-24 13:54:35 +00:00
media Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2011-03-19 22:27:06 -07:00
memstick
message Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-03-20 18:14:55 -07:00
mfd Merge branch 'devel-stable' of master.kernel.org:/home/rmk/linux-2.6-arm 2011-03-17 19:08:06 -07:00
misc drivers/misc/pch_phub.c: add MODULE_DEVICE_TABLE 2011-03-22 17:44:11 -07:00
mmc drivers/mmc/host/omap_hsmmc.c: use resource_size() 2011-03-22 17:44:15 -07:00
mtd Merge branch 'linux-next' of git://git.infradead.org/ubifs-2.6 2011-03-18 10:50:27 -07:00
net zlib: slim down zlib_deflate() workspace when possible 2011-03-22 17:44:17 -07:00
nfc
nubus
of
oprofile
parisc
parport
pci Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2011-03-18 10:56:44 -07:00
pcmcia
platform backlight: add backlight type 2011-03-22 17:43:59 -07:00
pnp pnp: only assign IORESOURCE_DMA if CONFIG_ISA_DMA_API is enabled 2011-03-22 17:44:16 -07:00
power
pps pps: remove unreachable code 2011-03-22 17:44:17 -07:00
ps3
rapidio
regulator
rtc rtc: add real-time clock driver for NVIDIA Tegra 2011-03-22 17:44:16 -07:00
s390
sbus
scsi sd: Fail discard requests when logical block provisioning has been disabled 2011-03-22 09:35:53 -07:00
sfi
sh
sn
spi Merge branch 'spi/next' of git://git.secretlab.ca/git/linux-2.6 2011-03-18 10:56:02 -07:00
ssb
staging backlight: add backlight type 2011-03-22 17:43:59 -07:00
target Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-03-18 10:37:40 -07:00
tc
telephony
thermal
tty tty: stop using "delayed_work" in the tty layer 2011-03-22 16:17:32 -07:00
uio
usb backlight: add backlight type 2011-03-22 17:43:59 -07:00
uwb
vhost
video kstrto*: converting strings to integers done (hopefully) right 2011-03-22 17:44:14 -07:00
virtio
vlynq
w1
watchdog Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-03-18 10:37:40 -07:00
xen
zorro
Kconfig
Makefile