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Peter Zijlstra 9ea4c38006 locking: Optimize lock_bh functions 
Currently all _bh_ lock functions do two preempt_count operations:

  local_bh_disable();
  preempt_disable();

and for the unlock:

  preempt_enable_no_resched();
  local_bh_enable();

Since its a waste of perfectly good cycles to modify the same variable
twice when you can do it in one go; use the new
__local_bh_{dis,en}able_ip() functions that allow us to provide a
preempt_count value to add/sub.

So define SOFTIRQ_LOCK_OFFSET as the offset a _bh_ lock needs to
add/sub to be done in one go.

As a bonus it gets rid of the preempt_enable_no_resched() usage.

This reduces a 1000 loops of:

  spin_lock_bh(&bh_lock);
  spin_unlock_bh(&bh_lock);

from 53596 cycles to 51995 cycles. I didn't do enough measurements to
say for absolute sure that the result is significant but the the few
runs I did for each suggest it is so.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: jacob.jun.pan@linux.intel.com
Cc: Mike Galbraith <bitbucket@online.de>
Cc: hpa@zytor.com
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: lenb@kernel.org
Cc: rjw@rjwysocki.net
Cc: rui.zhang@intel.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20131119151338.GF3694@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-13 13:47:36 +01:00
..
cpu sched: Add NEED_RESCHED to the preempt_count 2013-09-25 14:07:49 +02:00
debug kdb: Add support for external NMI handler to call KGDB/KDB 2013-10-03 18:47:54 +02:00
events perf: Disable all pmus on unthrottling and rescheduling 2013-12-17 15:04:00 +01:00
gcov gcov: reuse kbasename helper 2013-11-13 12:09:34 +09:00
irq Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-12-02 10:15:39 -08:00
locking sched/deadline: Add SCHED_DEADLINE inheritance logic 2014-01-13 13:42:56 +01:00
power PM / sleep: Fix memory leak in pm_vt_switch_unregister(). 2013-12-22 00:56:35 +01:00
printk printk.c: comments should refer to /proc/vmcore instead of /proc/vmcoreinfo 2013-11-13 12:09:14 +09:00
rcu NOHZ: Check for nohz active instead of nohz enabled 2013-11-19 14:59:50 +01:00
sched sched: Factor out the on_null_domain() checks in trigger_load_balance() 2014-01-13 13:47:35 +01:00
time nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off 2013-11-29 12:23:03 +01:00
trace sched/deadline: Add SCHED_DEADLINE inheritance logic 2014-01-13 13:42:56 +01:00
.gitignore Ignore generated file kernel/x509_certificate_list 2013-12-10 18:21:34 +00:00
acct.c
async.c
audit.c Merge git://git.infradead.org/users/eparis/audit 2013-11-21 19:18:14 -08:00
audit.h audit: call audit_bprm() only once to add AUDIT_EXECVE information 2013-11-05 11:15:03 -05:00
audit_tree.c kernel/audit_tree.c:audit_add_tree_rule(): protect `rule' from kill_rules() 2013-06-12 16:29:46 -07:00
audit_watch.c
auditfilter.c audit: do not reject all AUDIT_INODE filter types 2013-11-05 11:09:16 -05:00
auditsc.c audit: fix type of sessionid in audit_set_loginuid() 2013-11-06 11:47:24 -05:00
backtracetest.c
bounds.c mm: do not allocate page->ptl dynamically, if spinlock_t fits to long 2013-12-20 12:25:45 -08:00
capability.c xfs: update for v3.12-rc1 2013-09-09 11:19:09 -07:00
cgroup.c cgroup: don't recycle cgroup id until all csses' have been destroyed 2013-12-17 08:11:52 -05:00
cgroup_freezer.c cgroup: make css_for_each_descendant() and friends include the origin css in the iteration 2013-08-08 20:11:27 -04:00
compat.c
configs.c
context_tracking.c Linux 3.12-rc4 2013-10-09 12:36:13 +02:00
cpu.c Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-14 16:55:11 +09:00
cpu_pm.c
cpuset.c cpuset: Fix memory allocator deadlock 2013-11-27 13:52:47 -05:00
crash_dump.c
cred.c
delayacct.c kernel/delayacct.c: remove redundant checking in __delayacct_add_tsk() 2013-11-13 12:09:12 +09:00
dma.c
elfcore.c switch elf_core_write_extra_phdrs() to dump_emit() 2013-11-09 00:16:23 -05:00
exec_domain.c
exit.c ptrace: revert "Prepare to fix racy accesses on task breakpoints" 2013-07-09 10:33:26 -07:00
extable.c kernel/extable: fix address-checks for core_kernel and init areas 2013-11-28 09:49:41 -08:00
fork.c sched/deadline: Add SCHED_DEADLINE inheritance logic 2014-01-13 13:42:56 +01:00
freezer.c libata, freezer: avoid block device removal while system is frozen 2013-12-19 13:50:32 -05:00
futex.c rtmutex: Turn the plist into an rb-tree 2014-01-13 13:41:50 +01:00
futex_compat.c
groups.c userns: Kill nsown_capable it makes the wrong thing easy 2013-08-30 23:44:11 -07:00
hrtimer.c sched/deadline: Add SCHED_DEADLINE structures & implementation 2014-01-13 13:41:06 +01:00
hung_task.c Here are the 3.13 KVM changes. There was a lot of work on the PPC 2013-11-15 13:51:36 +09:00
irq_work.c
itimer.c
jump_label.c static_key: WARN on usage before jump_label_init was called 2013-10-19 19:45:35 -04:00
kallsyms.c
kcmp.c
Kconfig.freezer
Kconfig.hz kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS 2013-11-15 09:32:22 +09:00
Kconfig.locks
Kconfig.preempt
kexec.c kexec: migrate to reboot cpu 2013-12-18 19:04:50 -08:00
kmod.c kernel/kmod.c: check for NULL in call_usermodehelper_exec() 2013-09-30 14:31:02 -07:00
kprobes.c kprobes: use KSYM_NAME_LEN to size identifier buffers 2013-11-13 12:09:26 +09:00
ksysfs.c kernel: replace strict_strto*() with kstrto*() 2013-09-12 15:38:03 -07:00
kthread.c kthread: make kthread_create() killable 2013-11-13 12:08:59 +09:00
latencytop.c
Makefile KEYS: Remove files generated when SYSTEM_TRUSTED_KEYRING=y 2013-12-13 15:59:11 +00:00
module-internal.h KEYS: Separate the kernel signature checking keyring from module signing 2013-09-25 17:17:01 +01:00
module.c Mainly boring here, too. rmmod --wait finally removed, though. 2013-11-15 13:27:50 +09:00
module_signing.c keys: change asymmetric keys to use common hash definitions 2013-10-25 17:15:18 -04:00
notifier.c
nsproxy.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2013-09-07 14:35:32 -07:00
padata.c padata: make the sequence counter an atomic_t 2013-10-30 12:02:58 +08:00
panic.c kernel/panic.c: reduce 1 byte usage for print tainted buffer 2013-11-13 12:09:35 +09:00
params.c kernel/params: fix handling of signed integer types 2013-09-28 12:35:52 -07:00
pid.c pidns: fix free_pid() to handle the first fork failure 2013-09-30 14:31:03 -07:00
pid_namespace.c pid_namespace: make freeing struct pid_namespace rcu-delayed 2013-10-24 23:43:29 -04:00
posix-cpu-timers.c posix_timers: fix racy timer delta caching on task exit 2013-07-03 16:54:42 +02:00
posix-timers.c
profile.c kernel: delete __cpuinit usage from all core kernel files 2013-07-14 19:36:59 -04:00
ptrace.c exec/ptrace: fix get_dumpable() incorrect tests 2013-11-13 12:09:33 +09:00
range.c range: Do not add new blank slot with add_range_with_merge 2013-06-18 11:32:10 -05:00
reboot.c kexec: migrate to reboot cpu 2013-12-18 19:04:50 -08:00
relay.c kernel: delete __cpuinit usage from all core kernel files 2013-07-14 19:36:59 -04:00
res_counter.c memcg: reduce function dereference 2013-09-12 15:38:02 -07:00
resource.c kernel/resource.c: remove the unneeded assignment in function __find_resource 2013-07-03 16:08:06 -07:00
seccomp.c
signal.c constify copy_siginfo_to_user{,32}() 2013-11-09 00:16:29 -05:00
smp.c kernel: fix generic_exec_single indentation 2013-11-15 09:32:22 +09:00
smpboot.c kernel: delete __cpuinit usage from all core kernel files 2013-07-14 19:36:59 -04:00
smpboot.h
softirq.c locking: Optimize lock_bh functions 2014-01-13 13:47:36 +01:00
stacktrace.c
stop_machine.c stop_machine: Fix race between stop_two_cpus() and stop_cpus() 2013-11-11 12:43:38 +01:00
sys.c kernel/sys.c: remove obsolete #include <linux/kexec.h> 2013-11-13 12:09:13 +09:00
sys_ni.c
sysctl.c sched/deadline: Remove the sysctl_sched_dl knobs 2014-01-13 13:47:23 +01:00
sysctl_binary.c kernel/sysctl_binary.c: use scnprintf() instead of snprintf() 2013-11-13 12:09:33 +09:00
system_certificates.S KEYS: correct alignment of system_certificate_list content in assembly file 2013-12-10 18:25:28 +00:00
system_keyring.c KEYS: correct alignment of system_certificate_list content in assembly file 2013-12-10 18:25:28 +00:00
task_work.c task_work: documentation 2013-09-11 15:58:27 -07:00
taskstats.c genetlink: only pass array to genl_register_family_with_ops() 2013-11-19 16:39:05 -05:00
test_kprobes.c
time.c sched: Rename sched.c as sched/core.c in comments and Documentation 2013-06-19 12:58:42 +02:00
timeconst.bc
timer.c timer: Convert kmalloc_node(...GFP_ZERO...) to kzalloc_node(...) 2013-11-19 14:59:50 +01:00
tracepoint.c
tsacct.c
uid16.c userns: Kill nsown_capable it makes the wrong thing easy 2013-08-30 23:44:11 -07:00
up.c kernel: provide a __smp_call_function_single stub for !CONFIG_SMP 2013-11-15 09:32:22 +09:00
user-return-notifier.c
user.c KEYS: fix uninitialized persistent_keyring_register_sem 2013-12-13 15:59:11 +00:00
user_namespace.c KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 2013-09-24 10:35:19 +01:00
utsname.c userns: Kill nsown_capable it makes the wrong thing easy 2013-08-30 23:44:11 -07:00
utsname_sysctl.c
watchdog.c watchdog: update watchdog_thresh properly 2013-09-24 17:00:25 -07:00
workqueue.c PCI updates for v3.13: 2013-12-15 11:45:27 -08:00
workqueue_internal.h sched: Rename sched.c as sched/core.c in comments and Documentation 2013-06-19 12:58:42 +02:00