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d5b9dd04bd
linux-kernel-test/drivers
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Mikulas Patocka d5b9dd04bd dm: ignore merge_bvec for snapshots when safe 
Add a new flag DMF_MERGE_IS_OPTIONAL to struct mapped_device to indicate
whether the device can accept bios larger than the size its merge
function returns.  When set, use this to send large bios to snapshots
which can split them if necessary.  Snapshot I/O may be significantly
fragmented and this approach seems to improve peformance.

Before the patch, dm_set_device_limits restricted bio size to page size
if the underlying device had a merge function and the target didn't
provide a merge function.  After the patch, dm_set_device_limits
restricts bio size to page size if the underlying device has a merge
function, doesn't have DMF_MERGE_IS_OPTIONAL flag and the target doesn't
provide a merge function.

The snapshot target can't provide a merge function because when the merge
function is called, it is impossible to determine where the bio will be
remapped.  Previously this led us to impose a 4k limit, which we can
now remove if the snapshot store is located on a device without a merge
function.  Together with another patch for optimizing full chunk writes,
it improves performance from 29MB/s to 40MB/s when writing to the
filesystem on snapshot store.

If the snapshot store is placed on a non-dm device with a merge function
(such as md-raid), device mapper still limits all bios to page size.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-08-02 12:32:04 +01:00
..
accessibility
acpi Merge branch 'drm-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 2011-07-26 09:21:09 -07:00
amba
ata drivers: use kzalloc/kcalloc instead of 'kmalloc+memset', where possible 2011-07-25 20:57:13 -07:00
atm atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
auxdisplay
base atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
bcma Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-07-25 13:56:39 -07:00
block atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
bluetooth
cdrom
char Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6 2011-07-27 19:26:38 -07:00
clk
clocksource Merge branch 'timers-clocksource-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-07-23 10:34:47 -07:00
connector atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
cpufreq Merge branch 'drm-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 2011-07-26 09:21:09 -07:00
cpuidle
crypto Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2011-07-25 12:53:15 -07:00
dca
dio
dma Merge branch 'next/devel' of ssh://master.kernel.org/pub/scm/linux/kernel/git/arm/linux-arm-soc 2011-07-26 17:41:04 -07:00
edac atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
eisa eisa/pci_eisa.c: fix section mismatch 2011-07-25 20:57:14 -07:00
firewire atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
firmware Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2011-07-25 23:06:24 -07:00
gpio Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-07-25 13:56:39 -07:00
gpu atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
hid Merge branches 'roccat', 'upstream' and 'wiimote' into for-linus 2011-07-22 22:47:08 +02:00
hwmon atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
hwspinlock
i2c i2c-eg20t : Fix the issue of Combined R/W transfer mode 2011-07-27 00:02:28 +01:00
ide
idle
ieee802154
infiniband Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2011-07-27 13:21:40 -07:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2011-07-27 09:24:56 -07:00
iommu
isdn atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
leds arch/arm/mach-ux500/board-u5500.c: calibrate ALS input voltage 2011-07-25 20:57:15 -07:00
lguest lguest: Fix in/out emulation 2011-07-22 14:39:51 +09:30
macintosh drivers: fix up various ->llseek() implementations 2011-07-20 20:47:58 -04:00
mca
md dm: ignore merge_bvec for snapshots when safe 2011-08-02 12:32:04 +01:00
media atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
memstick
message atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
mfd Merge branch 'next/devel2' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/linux-arm-soc 2011-07-26 17:42:18 -07:00
misc atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
mmc MMC / TMIO: Fix build issue related to struct scatterlist 2011-07-26 11:52:55 -07:00
mtd Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-07-25 13:56:39 -07:00
net atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
nfc
nubus
of Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2011-07-25 22:59:39 -07:00
oprofile atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
parisc
parport Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6 2011-07-25 23:09:27 -07:00
pci Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2011-07-26 18:30:20 -07:00
pcmcia Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-07-25 13:56:39 -07:00
platform asus-wmi: ->is_visible() can't return negative 2011-07-24 10:12:19 -04:00
pnp Merge 'akpm' patch series 2011-07-25 21:00:19 -07:00
power
pps
ps3
ptp
rapidio
regulator regulator: Convert tps65023 to use regmap API 2011-07-23 07:57:02 +01:00
rtc rtc: fix hrtimer deadlock 2011-07-26 16:49:42 -07:00
s390 atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
sbus atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
scsi Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2011-07-27 13:21:40 -07:00
sfi
sh switch assorted clock drivers to debugfs_remove_recursive() 2011-07-20 20:47:51 -04:00
sn
spi Merge branch 'spi/next' of git://git.secretlab.ca/git/linux-2.6 2011-07-22 14:52:44 -07:00
ssb Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-07-25 13:56:39 -07:00
staging staging: brcm80211: Fix double include introduced by bad merge 2011-07-27 09:23:35 -07:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2011-07-27 13:21:40 -07:00
tc
telephony
thermal
tty atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
uio Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2011-07-25 23:06:24 -07:00
usb atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
uwb uwb: Fix misspelling of neighbourhood in comment 2011-07-21 14:03:41 +02:00
vhost atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
video atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
virt drivers/virt: add missing linux/interrupt.h to fsl_hypervisor.c 2011-07-22 09:24:39 -05:00
virtio virtio: expose for non-virtualization users too 2011-07-23 16:20:30 +09:30
vlynq
w1 atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
watchdog atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
xen xen/balloon: memory hotplug support for Xen balloon driver 2011-07-25 20:57:08 -07:00
zorro
Kconfig Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2011-07-25 22:59:39 -07:00
Makefile Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2011-07-25 22:59:39 -07:00