Waiman Long
a33fda35e3
locking/qspinlock: Introduce a simple generic 4-byte queued spinlock ...
This patch introduces a new generic queued spinlock implementation that
can serve as an alternative to the default ticket spinlock. Compared
with the ticket spinlock, this queued spinlock should be almost as fair
as the ticket spinlock. It has about the same speed in single-thread
and it can be much faster in high contention situations especially when
the spinlock is embedded within the data structure to be protected.
Only in light to moderate contention where the average queue depth
is around 1-3 will this queued spinlock be potentially a bit slower
due to the higher slowpath overhead.
This queued spinlock is especially suit to NUMA machines with a large
number of cores as the chance of spinlock contention is much higher
in those machines. The cost of contention is also higher because of
slower inter-node memory traffic.
Due to the fact that spinlocks are acquired with preemption disabled,
the process will not be migrated to another CPU while it is trying
to get a spinlock. Ignoring interrupt handling, a CPU can only be
contending in one spinlock at any one time. Counting soft IRQ, hard
IRQ and NMI, a CPU can only have a maximum of 4 concurrent lock waiting
activities. By allocating a set of per-cpu queue nodes and used them
to form a waiting queue, we can encode the queue node address into a
much smaller 24-bit size (including CPU number and queue node index)
leaving one byte for the lock.
Please note that the queue node is only needed when waiting for the
lock. Once the lock is acquired, the queue node can be released to
be used later.
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel J Blueman <daniel@numascale.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Douglas Hatch <doug.hatch@hp.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <paolo.bonzini@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1429901803-29771-2-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-05-08 12:36:25 +02:00
bpf: fix 64-bit divide
2015-04-27 23:11:49 -04:00
x86: Add "make tinyconfig" to configure the tiniest possible kernel
2014-08-08 16:30:24 -07:00
debug: prevent entering debug mode on panic/exception.
2015-02-19 12:39:03 -06:00
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
2015-04-15 09:00:47 -07:00
gcov: fix softlockups
2015-04-17 09:04:08 -04:00
irqchip core change for v4.1 (round 3)
2015-04-11 11:17:28 +02:00
Merge branch 'for-4.1/core-noarch' into for-linus
2015-04-13 23:57:20 +02:00
locking/qspinlock: Introduce a simple generic 4-byte queued spinlock
2015-05-08 12:36:25 +02:00
Merge back earlier suspend/hibernate material for v4.1.
2015-04-10 12:01:59 +02:00
TTY/Serial patches for 4.1-rc1
2015-04-21 09:33:10 -07:00
rcu: Control grace-period delays directly from value
2015-04-14 19:33:59 -07:00
Power management and ACPI fixes for v4.1-rc2
2015-04-30 14:23:31 -07:00
Char/Misc driver patches for 4.1-rc1
2015-04-21 09:42:58 -07:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2015-04-26 17:22:07 -07:00
acct: check FMODE_CAN_WRITE
2015-04-11 22:27:55 -04:00
kernel/async.c: switch to pr_foo()
2014-10-09 22:26:04 -04:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2015-04-26 17:22:07 -07:00
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-04-22 14:49:23 -07:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2015-04-26 17:22:07 -07:00
VFS: audit: d_backing_inode() annotations
2015-04-15 15:06:55 -04:00
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-02-11 20:07:47 -08:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2015-04-26 17:22:07 -07:00
page-cgroup: get rid of NR_PCG_FLAGS
2014-08-08 15:57:18 -07:00
kernel: conditionally support non-root users, groups and capabilities
2015-04-15 16:35:22 -07:00
cgroup: remove use of seq_printf return value
2015-04-15 16:35:25 -07:00
cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypes
2014-07-15 11:05:09 -04:00
all arches, signal: move restart_block to struct task_struct
2015-02-12 18:54:12 -08:00
context_tracking: Export context_tracking_user_enter/exit
2015-03-09 15:43:00 +01:00
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-04-14 13:36:04 -07:00
kernel, cpuset: remove exception for __GFP_THISNODE
2015-04-14 16:49:03 -07:00
crash_dump: Make is_kdump_kernel() accessible from modules
2014-08-25 15:42:19 -07:00
kernel: conditionally support non-root users, groups and capabilities
2015-04-15 16:35:22 -07:00
delayacct: Remove braindamaged type conversions
2014-07-23 10:18:06 -07:00
Remove rest of exec domains.
2015-04-12 21:03:31 +02:00
Remove execution domain support
2015-04-12 20:58:24 +02:00
ftrace/x86/extable: Add is_ftrace_trampoline() function
2014-11-19 15:25:26 -05:00
oprofile: reduce mmap_sem hold for mm->exe_file
2015-04-17 09:04:11 -04:00
freezer: remove obsolete comments in __thaw_task()
2014-10-21 23:44:20 +02:00
Linux 34.0-rc1
2015-02-24 08:41:07 +01:00
kernel: conditionally support non-root users, groups and capabilities
2015-04-15 16:35:22 -07:00
kernel/hung_task.c: change hung_task.c to use for_each_process_thread()
2015-04-15 16:35:22 -07:00
percpu: Convert remaining __get_cpu_var uses in 3.18-rcX
2014-10-29 11:18:18 -04:00
kernel/kallsyms.c: use __seq_open_private()
2014-10-14 02:18:16 +02:00
kcmp: fix standard comparison bug
2014-09-10 15:42:12 -07:00
locking/qspinlock: Introduce a simple generic 4-byte queued spinlock
2015-05-08 12:36:25 +02:00
kexec: allocate the kexec control page with KEXEC_CONTROL_MEMORY_GFP
2015-04-23 16:52:01 +02:00
usermodehelper: kill the kmod_thread_locker logic
2014-12-10 17:41:17 -08:00
kprobes: makes kprobes/enabled works correctly for optimized kprobes.
2015-02-13 21:21:42 -08:00
kernel/kthread.c: partial revert of 81c98869fa ("kthread: ensure locality of task_struct allocations")
2014-10-09 22:25:51 -04:00
modsign: change default key details
2015-04-30 09:35:41 -07:00
Quentin opened a can of worms by adding extable entry checking to modpost,
2015-04-22 09:49:24 -07:00
rcu: Make SRCU optional by using CONFIG_SRCU
2015-01-06 11:04:29 -08:00
bury struct proc_ns in fs/proc
2014-12-04 14:34:54 -05:00
padata: use %*pb[l] to print bitmaps including cpumasks and nodemasks
2015-02-13 21:21:38 -08:00
livepatch: kernel: add TAINT_LIVEPATCH
2014-12-22 15:40:48 +01:00
params: handle quotes properly for values not of form foo="bar".
2015-04-15 13:31:23 +09:30
fork: report pid reservation failure properly
2015-04-17 09:04:06 -04:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2014-12-16 15:53:03 -08:00
profile: use %*pb[l] to print bitmaps including cpumasks and nodemasks
2015-02-13 21:21:38 -08:00
ptrace: ptrace_detach() can no longer race with SIGKILL
2015-04-17 09:04:06 -04:00
kernel: avoid overflow in cmp_range
2015-01-17 10:02:23 +13:00
kernel/reboot.c: add orderly_reboot for graceful reboot
2015-04-15 16:35:23 -07:00
VFS: kernel/: d_inode() annotations
2015-04-15 15:06:55 -04:00
kernel/resource.c: remove deprecated __check_region() and friends
2015-04-15 16:35:22 -07:00
seccomp: cap SECCOMP_RET_ERRNO data to MAX_ERRNO
2015-02-17 14:34:55 -08:00
signal: remove warning about using SI_TKILL in rt_[tg]sigqueueinfo
2015-04-17 09:04:06 -04:00
smp: Fix error case handling in smp_call_function_*()
2015-04-19 13:19:23 -07:00
smpboot: Add common code for notification from dying CPU
2015-03-11 13:20:25 -07:00
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-02-09 15:24:03 -08:00
stacktrace: introduce snprint_stack_trace for buffer output
2014-12-13 12:42:48 -08:00
prctl: avoid using mmap_sem for exe_file serialization
2015-04-17 09:04:07 -04:00
kernel: conditionally support non-root users, groups and capabilities
2015-04-15 16:35:22 -07:00
kernel/sysctl.c: detect overflows when converting to int
2015-04-17 09:04:08 -04:00
kernel: add panic_on_warn
2014-12-10 17:41:10 -08:00
KEYS: validate certificate trust only with builtin keys
2014-07-17 09:35:17 -04:00
netlink: make nlmsg_end() and genlmsg_end() void
2015-01-18 01:03:45 -05:00
kernel/test_kprobes.c: use current logging functions
2014-08-08 15:57:18 -07:00
torture: Address race in module cleanup
2014-09-16 13:41:06 -07:00
sched: Make task->start_time nanoseconds based
2014-07-23 10:18:05 -07:00
groups: Consolidate the setgroups permission checks
2014-12-05 17:19:27 -06:00
scheduler: Replace __get_cpu_var with this_cpu_ptr
2014-08-26 13:45:45 -04:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2014-12-17 12:31:40 -08:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2014-12-17 12:31:40 -08:00
copy address of proc_ns_ops into ns_common
2014-12-04 14:34:47 -05:00
Merge branch 'akpm' (patches from Andrew)
2015-04-14 16:49:17 -07:00
workqueue: Reorder sysfs code
2015-04-06 11:16:04 -04:00
a33fda35e3