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android_kernel_motorola_sm6375/kernel
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Filename Latest commit message Latest commit date
David Miller 72c9ddfd4c ring-buffer: Make non-consuming read less expensive with lots of cpus. 
When performing a non-consuming read, a synchronize_sched() is
performed once for every cpu which is actively tracing.

This is very expensive, and can make it take several seconds to open
up the 'trace' file with lots of cpus.

Only one synchronize_sched() call is actually necessary.  What is
desired is for all cpus to see the disabling state change.  So we
transform the existing sequence:

	for_each_cpu() {
		ring_buffer_read_start();
	}

where each ring_buffer_start() call performs a synchronize_sched(),
into the following:

	for_each_cpu() {
		ring_buffer_read_prepare();
	}
	ring_buffer_read_prepare_sync();
	for_each_cpu() {
		ring_buffer_read_start();
	}

wherein only the single ring_buffer_read_prepare_sync() call needs to
do the synchronize_sched().

The first phase, via ring_buffer_read_prepare(), allocates the 'iter'
memory and increments ->record_disabled.

In the second phase, ring_buffer_read_prepare_sync() makes sure this
->record_disabled state is visible fully to all cpus.

And in the final third phase, the ring_buffer_read_start() calls reset
the 'iter' objects allocated in the first phase since we now know that
none of the cpus are adding trace entries any more.

This makes openning the 'trace' file nearly instantaneous on a
sparc64 Niagara2 box with 128 cpus tracing.

Signed-off-by: David S. Miller <davem@davemloft.net>
LKML-Reference: <20100420.154711.11246950.davem@davemloft.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2010-04-27 13:06:35 -04:00
..
gcov
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 ring-buffer: Make non-consuming read less expensive with lots of cpus. 2010-04-27 13:06:35 -04:00
.gitignore
acct.c copy_signal() cleanup: kill taskstats_tgid_init() and acct_init_pacct() 2010-03-12 15:52:39 -08:00
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
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 kbuild: move bounds.h to include/generated 2009-12-12 13:08:14 +01:00
capability.c capabilities: Use RCU to protect task lookup in sys_capget 2009-12-10 09:42:48 +11:00
cgroup.c cgroups: remove duplicate include 2010-03-24 16:31:19 -07:00
cgroup_freezer.c Merge branch 'master' into export-slabh 2010-04-05 11:37:28 +09:00
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 Merge branch 'master' into export-slabh 2010-04-05 11:37:28 +09:00
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 elf coredump: add extended numbering support 2010-03-06 11:26:46 -08:00
exec_domain.c
exit.c mm: avoid null-pointer deref in sync_mm_rss() 2010-04-07 08:38:02 -07:00
extable.c
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 futex: Protect pid lookup in compat code with RCU 2009-12-09 14:22:14 +01:00
groups.c
hrtimer.c hrtimers: Convert to raw_spinlocks 2009-12-14 23:55:34 +01:00
hung_task.c softlockup: Fix hung_task_check_count sysctl 2009-11-27 06:21:57 +01:00
hw_breakpoint.c Merge branch 'perf/core' into perf/urgent 2010-03-04 11:47:52 +01:00
itimer.c itimers: Fix racy writes to cpu_itimer fields 2009-11-18 16:32:12 +01:00
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 mutex: Better control mutex adaptive spinning config 2009-12-03 11:50:11 +01:00
Kconfig.preempt
kexec.c percpu: add __percpu sparse annotations to core kernel subsystems 2010-02-17 11:17:38 +09:00
kfifo.c kfifo: Don't use integer as NULL pointer 2010-02-16 15:11:08 -08:00
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 kprobes: Calculate the index correctly when freeing the out-of-line execution slot 2010-03-11 14:06:16 +01:00
ksysfs.c Merge branch 'for-next' into for-linus 2010-03-08 16:55:37 +01:00
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 Merge branch 'slabh' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc 2010-04-05 09:39:11 -07:00
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
Makefile elf coredump: replace ELF_CORE_EXTRA_* macros by functions 2010-03-06 11:26:45 -08:00
module.c Merge branch 'linus' into tracing/core 2010-04-08 10:18:47 +02:00
mutex-debug.c headers: remove sched.h from interrupt.h 2009-10-11 11:20:58 -07:00
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 sched: Use lockdep-based checking on rcu_dereference() 2010-02-25 10:34:26 +01:00
ns_cgroup.c
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 Merge branch 'master' into export-slabh 2010-04-05 11:37:28 +09:00
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 pm_qos: clean up racy global "name" variable 2009-10-14 15:31:10 +02:00
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 posix-timers.c: Don't export local functions 2010-02-05 14:54:10 +01:00
printk.c printk: avoid warning when CONFIG_PRINTK is disabled 2010-03-06 11:26:33 -08:00
profile.c
ptrace.c ptrace: Fix ptrace_regset() comments and diagnose errors specifically 2010-02-23 13:45:26 -08:00
range.c x86: Change range end to start+size 2010-02-10 17:47:17 -08:00
rcupdate.c rcu: Make RCU lockdep check the lockdep_recursion variable 2010-04-19 08:37:19 +02:00
rcutiny.c rcu: Eliminate unneeded function wrapping 2009-11-22 18:58:16 +01:00
rcutorture.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2010-03-03 07:34:18 -08:00
rcutree.c rcu: Fix accelerated grace periods for last non-dynticked CPU 2010-02-27 09:53:52 +01:00
rcutree.h rcu: Increase RCU CPU stall timeouts if PROVE_RCU 2010-03-11 13:38:01 +01:00
rcutree_plugin.h rcu: Fix holdoff for accelerated GPs for last non-dynticked CPU 2010-02-28 09:17:42 +01:00
rcutree_trace.c rcu: Stop overflowing signed integers 2010-02-25 10:34:57 +01:00
relay.c splice: comparing unsigned int < 0 2010-03-06 11:26:32 -08:00
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 sched: Convert pi_lock to raw_spinlock 2009-12-14 23:55:33 +01:00
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c rtmutes: Convert rtmutex.lock to raw_spinlock 2009-12-14 23:55:33 +01:00
rtmutex.h
rtmutex_common.h
rwsem.c
sched.c Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-04-08 08:37:05 -07:00
sched_clock.c sched: Fix cpu_clock() in NMIs, on !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK 2009-12-15 09:04:36 +01:00
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: Convert cpupri lock to raw_spinlock 2009-12-14 23:55:33 +01:00
sched_debug.c sched: Fix proc_sched_set_task() 2010-04-02 20:06:40 +02:00
sched_fair.c sched, rcu: Fix rcu_dereference() for RCU-lockdep 2010-03-01 09:29:58 +01:00
sched_features.h sched: Discard some old bits 2009-12-09 10:03:07 +01:00
sched_idletask.c sched: Remove the sched_class load_balance methods 2010-01-21 13:40:09 +01:00
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 kernel core: use helpers for rlimits 2010-03-06 11:26:33 -08:00
slow-work-debugfs.c SLOW_WORK: Move slow_work's proc file to debugfs 2009-12-01 08:20:31 -08:00
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 hrtimer, softirq: Fix hrtimer->softirq trampoline 2010-02-03 18:17:40 +01:00
softlockup.c softlockup: Stop spurious softlockup messages due to overflow 2010-03-21 19:30:13 +01:00
spinlock.c locking: Cleanup the name space completely 2009-12-14 23:55:33 +01:00
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 percpu: add __percpu sparse annotations to core kernel subsystems 2010-02-17 11:17:38 +09:00
sys.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
sys_ni.c Add generic sys_ipc wrapper 2010-03-12 15:52:32 -08:00
sysctl.c sysctl extern cleanup: lockdep 2010-03-12 15:53:10 -08:00
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 ipv4 05/05: add sysctl to accept packets with local source addresses 2009-12-03 12:14:38 -08:00
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
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
tsacct.c mm: clean up mm_counter 2010-03-06 11:26:23 -08:00
uid16.c
up.c
user-return-notifier.c core: Clean up user return notifers use of per_cpu 2009-12-02 10:22:59 +01:00
user.c sched: Remove USER_SCHED 2010-01-21 13:40:18 +01:00
user_namespace.c
utsname.c
utsname_sysctl.c sysctl kernel: Remove binary sysctl logic 2009-11-12 02:04:55 -08:00
wait.c
workqueue.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2009-12-10 09:35:44 -08:00