linux/kernel
Paul E. McKenney d21670acab rcu: reduce the number of spurious RCU_SOFTIRQ invocations
Lai Jiangshan noted that up to 10% of the RCU_SOFTIRQ are spurious, and
traced this down to the fact that the current grace-period machinery
will uselessly raise RCU_SOFTIRQ when a given CPU needs to go through
a quiescent state, but has not yet done so.  In this situation, there
might well be nothing that RCU_SOFTIRQ can do, and the overhead can be
worth worrying about in the ksoftirqd case.  This patch therefore avoids
raising RCU_SOFTIRQ in this situation.

Changes since v1 (http://lkml.org/lkml/2010/3/30/122 from Lai Jiangshan):

o	Omit the rcu_qs_pending() prechecks, as they aren't that
	much less expensive than the quiescent-state checks.

o	Merge with the set_need_resched() patch that reduces IPIs.

o	Add the new n_rp_report_qs field to the rcu_pending tracing output.

o	Update the tracing documentation accordingly.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2010-05-10 11:08:35 -07:00
..
gcov microblaze: Enable GCOV_PROFILE_ALL 2009-09-21 14:29:21 +02:00
irq Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-04-06 13:03:22 -07:00
power PM / Hibernate: user.c, fix SNAPSHOT_SET_SWAP_AREA handling 2010-04-10 22:28:56 +02:00
time include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
trace Merge branch 'master' into export-slabh 2010-04-05 11:37:28 +09:00
.gitignore
acct.c
async.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
audit.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
audit.h Fix rule eviction order for AUDIT_DIR 2009-06-24 00:02:38 -04:00
audit_tree.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
audit_watch.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
auditfilter.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
auditsc.c audit: preface audit printk with audit 2010-04-05 13:19:45 -07:00
backtracetest.c
bounds.c
capability.c
cgroup.c cgroup: Fix an RCU warning in alloc_css_id() 2010-05-04 09:25:00 -07:00
cgroup_freezer.c rcu: Fix RCU lockdep splat on freezer_fork path 2010-04-30 12:03:17 +02:00
compat.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
configs.c
cpu.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
cpuset.c cpuset: alloc nodemask_t on the heap rather than the stack 2010-03-24 16:31:21 -07:00
cred-internals.h
cred.c CRED: Fix a race in creds_are_invalid() in credentials debugging 2010-04-22 09:14:29 +10:00
delayacct.c
dma.c
early_res.c x86: Do not free zero sized per cpu areas 2010-03-29 18:55:40 +02:00
elfcore.c
exec_domain.c
exit.c mm: avoid null-pointer deref in sync_mm_rss() 2010-04-07 08:38:02 -07:00
extable.c Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
fork.c mm: avoid null-pointer deref in sync_mm_rss() 2010-04-07 08:38:02 -07:00
freezer.c
futex.c futex: Handle futex value corruption gracefully 2010-02-03 15:13:22 +01:00
futex_compat.c
groups.c
hrtimer.c
hung_task.c
hw_breakpoint.c
itimer.c
kallsyms.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c percpu: add __percpu sparse annotations to core kernel subsystems 2010-02-17 11:17:38 +09:00
kfifo.c
kgdb.c kgdb: Turn off tracing while in the debugger 2010-04-02 14:58:19 -05:00
kmod.c kmod: fix resource leak in call_usermodehelper_pipe() 2010-01-11 09:34:04 -08:00
kprobes.c
ksysfs.c
kthread.c cpuset: fix the problem that cpuset_mem_spread_node() returns an offline node 2010-03-24 16:31:21 -07:00
latencytop.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
lockdep.c rcu: optionally leave lockdep enabled after RCU lockdep splat 2010-05-10 11:08:31 -07:00
lockdep_internals.h lockdep: BFS cleanup 2009-07-24 10:53:29 +02:00
lockdep_proc.c seq_file: constify seq_operations 2009-09-23 07:39:29 -07:00
lockdep_states.h
Makefile
module.c Fix up possibly racy module refcounting 2010-04-05 19:50:02 -07:00
mutex-debug.c
mutex-debug.h locking: Implement new raw_spinlock 2009-12-14 23:55:32 +01:00
mutex.c mutex: Better control mutex adaptive spinning config 2009-12-03 11:50:11 +01:00
mutex.h
notifier.c
ns_cgroup.c cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time 2009-09-24 07:20:58 -07:00
nsproxy.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
padata.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
panic.c panic: fix panic_timeout accuracy when running on a hypervisor 2010-03-06 11:26:33 -08:00
params.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2010-03-12 16:04:50 -08:00
perf_event.c perf: Fix resource leak in failure path of perf_event_open() 2010-05-01 13:11:25 +02:00
pid.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-03-13 14:43:01 -08:00
pid_namespace.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
pm_qos_params.c
posix-cpu-timers.c Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-03-26 15:10:38 -07:00
posix-timers.c
printk.c printk: avoid warning when CONFIG_PRINTK is disabled 2010-03-06 11:26:33 -08:00
profile.c
ptrace.c
range.c
rcupdate.c rcu: slim down rcutiny by removing rcu_scheduler_active and friends 2010-05-10 11:08:34 -07:00
rcutiny.c rcu: slim down rcutiny by removing rcu_scheduler_active and friends 2010-05-10 11:08:34 -07:00
rcutiny_plugin.h rcu: slim down rcutiny by removing rcu_scheduler_active and friends 2010-05-10 11:08:34 -07:00
rcutorture.c
rcutree.c rcu: reduce the number of spurious RCU_SOFTIRQ invocations 2010-05-10 11:08:35 -07:00
rcutree.h rcu: reduce the number of spurious RCU_SOFTIRQ invocations 2010-05-10 11:08:35 -07:00
rcutree_plugin.h rcu: print boot-time console messages if RCU configs out of ordinary 2010-05-10 11:08:34 -07:00
rcutree_trace.c rcu: reduce the number of spurious RCU_SOFTIRQ invocations 2010-05-10 11:08:35 -07:00
relay.c
res_counter.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
resource.c resources: add interfaces that return conflict information 2010-03-23 13:33:50 -07:00
rtmutex-debug.c
rtmutex-debug.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rtmutex-tester.c
rtmutex.c
rtmutex.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rtmutex_common.h rt_mutex: add proxy lock routines 2009-04-06 11:14:02 +02:00
rwsem.c
sched.c rcu: refactor RCU's context-switch handling 2010-05-10 11:08:33 -07:00
sched_clock.c
sched_cpupri.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
sched_cpupri.h
sched_debug.c sched: Fix an RCU warning in print_task() 2010-05-04 09:25:01 -07:00
sched_fair.c
sched_features.h
sched_idletask.c
sched_rt.c Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-03-13 14:46:18 -08:00
sched_stats.h
seccomp.c
semaphore.c
signal.c
slow-work-debugfs.c
slow-work.c slow-work: use get_ref wrapper instead of directly calling get_ref 2010-03-29 09:13:30 -07:00
slow-work.h SLOW_WORK: CONFIG_SLOW_WORK_PROC should be CONFIG_SLOW_WORK_DEBUG 2010-03-29 09:14:47 -07:00
smp.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
softirq.c rcu: refactor RCU's context-switch handling 2010-05-10 11:08:33 -07:00
softlockup.c softlockup: Stop spurious softlockup messages due to overflow 2010-03-21 19:30:13 +01:00
spinlock.c
srcu.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
stacktrace.c
stop_machine.c
sys.c kernel/sys.c: fix compat uname machine 2010-04-24 11:31:24 -07:00
sys_ni.c Add generic sys_ipc wrapper 2010-03-12 15:52:32 -08:00
sysctl.c
sysctl_binary.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
sysctl_check.c
taskstats.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
test_kprobes.c
time.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
timeconst.pl Make constants in kernel/timeconst.h fixed 64 bits 2008-05-02 16:18:42 -07:00
timer.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
tracepoint.c trivial: fix typo "to to" in multiple files 2009-09-21 15:14:55 +02:00
tsacct.c
uid16.c headers: utsname.h redux 2009-09-23 18:13:10 -07:00
up.c
user-return-notifier.c
user.c sched: Remove USER_SCHED 2010-01-21 13:40:18 +01:00
user_namespace.c
utsname.c
utsname_sysctl.c
wait.c
workqueue.c workqueue: flush_delayed_work: keep the original workqueue for re-queueing 2010-04-30 07:24:51 +02:00