Oleg Nesterov
a1fd3e24d8
percpu_rw_semaphore: reimplement to not block the readers unnecessarily ...
Currently the writer does msleep() plus synchronize_sched() 3 times to
acquire/release the semaphore, and during this time the readers are
blocked completely. Even if the "write" section was not actually started
or if it was already finished.
With this patch down_write/up_write does synchronize_sched() twice and
down_read/up_read are still possible during this time, just they use the
slow path.
percpu_down_write() first forces the readers to use rw_semaphore and
increment the "slow" counter to take the lock for reading, then it
takes that rw_semaphore for writing and blocks the readers.
Also. With this patch the code relies on the documented behaviour of
synchronize_sched(), it doesn't try to pair synchronize_sched() with
barrier.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-17 17:15:18 -08:00
ARM: 7588/1: amba: create a resource parent registrator
2012-12-03 11:15:35 +00:00
Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus
2012-12-14 14:27:45 -08:00
ARM: arm-soc: Updates for Marvell mvebu/kirkwood
2012-12-14 14:54:26 -08:00
This is the MFD patch set for the 3.8 merge window.
2012-12-16 18:55:20 -08:00
iio:imu: Add support for the ADIS16480 and similar IMUs
2012-11-20 21:28:51 +00:00
This is the MFD patch set for the 3.8 merge window.
2012-12-16 18:55:20 -08:00
ARM: arm-soc: Device-tree updates, take 2
2012-12-14 14:42:53 -08:00
This is the MFD patch set for the 3.8 merge window.
2012-12-16 18:55:20 -08:00
mlx4: 64-byte CQE/EQE support
2012-11-26 10:19:17 -08:00
MMC highlights for 3.8:
2012-12-11 11:19:09 -08:00
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/jesse/openvswitch
2012-11-30 12:01:30 -05:00
pinctrl: generic: add input schmitt disable parameter
2012-11-21 08:55:26 +01:00
drivers/video/backlight/lp855x_bl.c: use generic PWM functions
2012-12-17 17:15:16 -08:00
Highlights:
2012-12-13 19:26:04 -08:00
Merge remote-tracking branch 'regulator/topic/tol' into regulator-next
2012-12-10 12:43:22 +09:00
Linux 3.7-rc8
2012-12-07 17:02:47 +00:00
Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus
2012-12-14 14:27:45 -08:00
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
2012-12-12 18:07:07 -08:00
Merge branch 'x86-acpi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-12-14 10:03:23 -08:00
gpio / ACPI: add ACPI support
2012-11-30 12:37:36 +01:00
Revert "libata: check SATA_SETTINGS log with HW Feature Ctrl"
2012-12-14 09:34:01 -05:00
pata_platform: remove unused remove function
2012-12-03 05:15:33 -05:00
ath9k: allow to load EEPROM content via firmware API
2012-12-10 15:49:57 -05:00
atm: add release_cb() callback to vcc
2012-12-02 00:05:12 +00:00
Revert "bdi: add a user-tunable cpu_list for the bdi flusher threads"
2012-12-17 11:29:09 -08:00
backlight: add of_find_backlight_by_node()
2012-12-17 17:15:16 -08:00
mm: introduce a common interface for balloon pages mobility
2012-12-11 17:22:26 -08:00
ssb/bcma: add common header for watchdog
2012-12-06 14:58:56 -05:00
get rid of pt_regs argument of ->load_binary()
2012-11-28 21:53:38 -05:00
block: discard granularity might not be power of 2
2012-12-14 20:46:04 +01:00
mm/bootmem.c: remove unused wrapper function reserve_bootmem_generic()
2012-12-12 17:38:35 -08:00
bsg: Remove unused function bsg_goose_queue()
2012-12-06 14:33:02 +01:00
include/linux/bug.h: fix sparse warning related to BUILD_BUG_ON_INVALID
2012-11-26 17:41:24 -08:00
The common clock framework changes for 3.8 are comprised of lots of
2012-12-11 11:25:08 -08:00
make compat_do_execve() static, lose pt_regs argument
2012-11-28 21:53:37 -05:00
context_tracking: New context tracking susbsystem
2012-11-30 11:40:07 -08:00
do_coredump(): get rid of pt_regs argument
2012-11-29 00:01:25 -05:00
thermal: cpu cooling: allow module builds
2012-11-22 15:59:52 +08:00
cpuset: use N_MEMORY instead N_HIGH_MEMORY
2012-12-12 17:38:32 -08:00
PM / devfreq: remove compiler error when a governor is module
2012-11-26 19:17:44 +09:00
Merge branch 'x86-ras-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-12-14 09:59:59 -08:00
common: DMA-mapping: add DMA_ATTR_FORCE_CONTIGUOUS attribute
2012-11-29 03:30:34 -08:00
drivers: cma: represent physical addresses as phys_addr_t
2012-12-11 09:28:09 +01:00
EDAC: Fix csrow size reported in sysfs
2012-11-28 11:54:40 +01:00
Revert "x86-64/efi: Use EFI to deal with platform wall clock (again)"
2012-12-15 15:20:41 -08:00
extcon: kernel_doc style fix
2012-11-22 13:43:27 +09:00
kill daemonize()
2012-11-28 21:49:02 -05:00
Merge branch 'for-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2012-12-12 08:18:24 -08:00
lseek: the "whence" argument is called "whence"
2012-12-17 17:15:12 -08:00
kill daemonize()
2012-11-28 21:49:02 -05:00
drivers/video: fsl-diu-fb: add support for set_gamma ioctls
2012-11-26 13:41:19 -06:00
lseek: the "whence" argument is called "whence"
2012-12-17 17:15:12 -08:00
mm: add a reminder comment for __GFP_BITS_SHIFT
2012-12-12 17:38:34 -08:00
gpiolib: rename pin range arguments
2012-11-21 10:07:48 +01:00
propagate name change to comments in kernel source
2012-12-06 10:39:54 +01:00
HID: sensors: autodetect USB HID sensor hubs
2012-12-12 16:49:10 +01:00
Merge branches 'for-3.7/upstream-fixes', 'for-3.8/hidraw', 'for-3.8/i2c-hid', 'for-3.8/multitouch', 'for-3.8/roccat', 'for-3.8/sensors' and 'for-3.8/upstream' into for-linus
2012-12-12 21:41:55 +01:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
i2c / ACPI: add ACPI enumeration support
2012-11-23 12:23:40 +01:00
wireless: fix VHT max AMPDU exponent definition
2012-12-06 14:02:51 +01:00
netconf: advertise mc_forwarding status
2012-12-04 13:08:10 -05:00
include/linux/init.h: use the stringify operator for the __define_initcall macro
2012-12-17 17:15:12 -08:00
net: Add support for hardware-offloaded encapsulation
2012-12-09 00:20:28 -05:00
ipack: remove use of __devinitconst
2012-11-21 15:09:26 -08:00
net: Add support for hardware-offloaded encapsulation
2012-12-09 00:20:28 -05:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
2012-12-13 14:20:19 -08:00
Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-12-11 18:14:31 -08:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2012-12-16 15:40:50 -08:00
kobject: remove CONFIG_HOTPLUG ifdefs
2012-11-28 10:33:03 -08:00
Merge tag 'kvm-3.8-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm
2012-12-13 15:31:08 -08:00
led: Add dependency on CONFIG_LEDS_TRIGGERS to led_trigger_rename_static()
2012-11-26 14:28:51 -08:00
libata: implement ata_platform_remove_one()
2012-12-03 05:15:17 -05:00
mm, memcg: avoid unnecessary function call when memcg is disabled
2012-12-12 17:38:34 -08:00
hotplug: update nodemasks management
2012-12-12 17:38:33 -08:00
mm, memory-hotplug: dynamic configure movable memory and portion memory
2012-12-11 17:22:28 -08:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
net: add micrel KSZ8873MLL switch support
2012-11-23 14:29:51 -05:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
[SCSI] miscdevice: Adding support for MPT3SAS_MINOR(222)
2012-12-01 10:07:54 +00:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
2012-12-13 12:00:02 -08:00
mm: cleanup register_node()
2012-12-11 17:22:27 -08:00
numa: add CONFIG_MOVABLE_NODE for movable-dedicated node
2012-12-12 17:38:34 -08:00
of: *node argument to of_parse_phandle_with_args should be const
2012-12-11 17:30:16 +00:00
of/address: sparc: Declare of_iomap as an extern function for sparc again
2012-11-23 22:01:15 +00:00
of/i2c: add dummy inline functions for when CONFIG_OF_I2C(_MODULE) isn't defined
2012-12-11 17:30:16 +00:00
ARM: OMAP: Move plat-omap/dma-omap.h to include/linux/omap-dma.h
2012-11-30 08:41:50 -08:00
ARM: OMAP2+: Move plat/iovmm.h to include/linux/omap-iommu.h
2012-11-20 10:04:29 -08:00
mm, oom: fix race when specifying a thread as the oom origin
2012-12-11 17:22:27 -08:00
openvswitch: add skb mark matching and set action
2012-11-26 11:33:18 -08:00
memory-hotplug: skip HWPoisoned page when offlining pages
2012-12-11 17:22:22 -08:00
mm: introduce a common interface for balloon pages mobility
2012-12-11 17:22:26 -08:00
PCI changes for the v3.8 merge window:
2012-12-13 12:14:47 -08:00
tty/8250 Add support for Commtech's Fastcom Async-335 and Fastcom Async-PCIe cards
2012-11-21 16:31:17 -08:00
percpu_rw_semaphore: reimplement to not block the readers unnecessarily
2012-12-17 17:15:18 -08:00
ACPI / platform: Initialize ACPI handles of platform devices in advance
2012-11-21 00:21:59 +01:00
efi_pstore: Add a sequence counter to a variable name
2012-11-26 16:07:44 -08:00
get rid of ptrace_signal_deliver() arguments
2012-11-29 00:01:24 -05:00
time: export time information for KVM pvclock
2012-11-27 23:29:12 -02:00
context_tracking: New context tracking susbsystem
2012-11-30 11:40:07 -08:00
Merge remote-tracking branch 'regmap/topic/table' into regmap-next
2012-12-11 12:39:32 +09:00
res_counter: delete res_counter_write()
2012-12-12 17:38:33 -08:00
mm/rmap, migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable
2012-12-11 14:43:00 +00:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
mm: support more pagesizes for MAP_HUGETLB/SHM_HUGETLB
2012-12-11 17:22:25 -08:00
net: Add support for hardware-offloaded encapsulation
2012-12-09 00:20:28 -05:00
net: phy: smsc: force all capable mode if the phy is started in powerdown mode
2012-12-07 12:48:00 -05:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
2012-12-13 12:00:02 -08:00
string: introduce helper to get base file name from given path
2012-12-17 17:15:17 -08:00
lseek: the "whence" argument is called "whence"
2012-12-17 17:15:12 -08:00
net: Add support for hardware-offloaded encapsulation
2012-12-09 00:20:28 -05:00
Thermal: Fix DEFAULT_THERMAL_GOVERNOR
2012-12-12 15:34:48 +08:00
mm, oom: fix race when specifying a thread as the oom origin
2012-12-11 17:22:27 -08:00
net: Add support for hardware-offloaded encapsulation
2012-12-09 00:20:28 -05:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
mm: numa: Add pte updates, hinting and migration stats
2012-12-11 14:42:48 +00:00
writeback: remove nr_pages_dirtied arg from balance_dirty_pages_ratelimited_nr()
2012-12-11 17:22:21 -08:00
