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Kan Liang 40999312c7 perf/core: Try parent PMU first when initializing a child event 
perf has additional overhead when monitoring the task which
frequently generates child tasks.

perf_init_event() is one of the hotspots for the additional overhead:

Currently, to get the PMU, it tries to search the type in pmu_idr at
first. But it is not always successful, especially for the widely used
PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE events. So it has to go to the
slow path which go through the whole PMUs list.

It will be a big performance issue, if the PMUs list is long (e.g. server
with many uncore boxes) and the task frequently generates child tasks.

The child event inherits its parent event. So the child event should
try its parent PMU first.

Here is some data from the overhead test on Broadwell server:

  perf record -e $TEST_EVENTS -- ./loop.sh 50000

  loop.sh
    start=$(date +%s%N)
    i=0
    while [ "$i" -le "$1" ]
    do
            date > /dev/null
            i=`expr $i + 1`
    done
    end=$(date +%s%N)
    elapsed=`expr $end - $start`

  Event#	Original elapsed time	Elapsed time with patch		delta
  1		196,573,192,397		189,162,029,998			-3.77%
  2		257,567,753,013		241,620,788,683			-6.19%
  4		398,730,726,971		370,518,938,714			-7.08%
  8		824,983,761,120		740,702,489,329			-10.22%
  16		1,883,411,923,498	1,672,027,508,355		-11.22%

... which shows a nice performance improvement.

Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1484745662-15928-2-git-send-email-kan.liang@intel.com
[ Tidied up the changelog and the code comment. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-30 12:01:16 +01:00
..
bpf bpf: don't trigger OOM killer under pressure with map alloc 2017-01-18 17:12:26 -05:00
configs config: android: enable CONFIG_SECCOMP 2016-10-11 15:06:32 -07:00
debug kdb: call vkdb_printf() from vprintk_default() only when wanted 2016-12-14 16:04:08 -08:00
events perf/core: Try parent PMU first when initializing a child event 2017-01-30 12:01:16 +01:00
gcov gcov: add support for gcc version >= 6 2016-07-15 14:54:27 +09:00
irq genirq/affinity: Fix node generation from cpumask 2016-12-15 12:32:35 +01:00
livepatch livepatch/module: make TAINT_LIVEPATCH module-specific 2016-08-26 14:42:08 +02:00
locking Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
power Merge branches 'pm-sleep' and 'pm-cpufreq' 2017-01-27 00:08:59 +01:00
printk Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
rcu rcu: Narrow early boot window of illegal synchronous grace periods 2017-01-14 21:23:48 -08:00
sched ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
time nohz: Fix collision between tick and other hrtimers 2017-01-11 10:41:33 +01:00
trace clocksource: Use a plain u64 instead of cycle_t 2016-12-25 11:04:12 +01:00
.gitignore
acct.c
async.c
audit_fsnotify.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
audit_tree.c Merge branch 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit 2017-01-05 23:06:06 -08:00
audit_watch.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
audit.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
audit.h audit_log_{name,link_denied}: constify struct path 2016-12-05 19:00:38 -05:00
auditfilter.c audit: add support for session ID user filter 2016-11-29 15:10:12 -05:00
auditsc.c Merge branch 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit 2016-12-14 14:06:40 -08:00
backtracetest.c
bounds.c
capability.c capability: export has_capability 2017-01-12 07:01:56 -07:00
cgroup_freezer.c
cgroup_pids.c cgroup: Use lld instead of ld when printing pids controller events_limit 2016-06-21 15:03:36 -04:00
cgroup.c cgroup: add support for eBPF programs 2016-11-25 16:25:52 -05:00
compat.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
configs.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
context_tracking.c
cpu_pm.c
cpu.c cpu/hotplug: Remove unused but set variable in _cpu_down() 2017-01-18 11:55:09 +01:00
cpuset.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
crash_dump.c
cred.c cred: Reject inodes with invalid ids in set_create_file_as() 2016-06-30 18:05:09 -05:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
extable.c kprobes, extable: Identify kprobes trampolines as kernel text area 2017-01-14 08:38:05 +01:00
fork.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
freezer.c freezer, oom: check TIF_MEMDIE on the correct task 2016-07-28 16:07:41 -07:00
futex_compat.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
futex.c ktime: Get rid of the union 2016-12-25 17:21:22 +01:00
groups.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
hung_task.c hung_task: decrement sysctl_hung_task_warnings only if it is positive 2016-12-12 18:55:09 -08:00
irq_work.c
jump_label.c jump_labels: API for flushing deferred jump label updates 2017-01-12 14:33:16 +01:00
kallsyms.c
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/mutex: Allow MUTEX_SPIN_ON_OWNER when DEBUG_MUTEXES 2016-10-25 11:31:51 +02:00
Kconfig.preempt
kcov.c kcov: make kcov work properly with KASLR enabled 2016-12-20 09:48:47 -08:00
kexec_core.c kexec: add cond_resched into kimage_alloc_crash_control_pages 2016-12-14 16:04:07 -08:00
kexec_file.c ima: on soft reboot, save the measurement list 2016-12-20 09:48:44 -08:00
kexec_internal.h kexec_file: Allow arch-specific memory walking for kexec_add_buffer 2016-11-30 23:14:57 +11:00
kexec.c kexec: allow architectures to override boot mapping 2016-08-02 19:35:27 -04:00
kmod.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
kprobes.c kprobes, extable: Identify kprobes trampolines as kernel text area 2017-01-14 08:38:05 +01:00
ksysfs.c kexec: add a kexec_crash_loaded() function 2016-08-02 19:35:30 -04:00
kthread.c kthread: add __printf attributes 2016-12-12 18:55:06 -08:00
latencytop.c
Makefile Merge branch 'akpm' (patches from Andrew) 2016-12-14 17:25:18 -08:00
membarrier.c
memremap.c mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done} 2017-01-10 18:31:54 -08:00
module_signing.c
module-internal.h
module.c taint/module: Fix problems when out-of-kernel driver defines true or false 2017-01-17 10:56:45 -08:00
notifier.c
nsproxy.c
padata.c padata: Remove unused but set variables 2016-10-25 11:08:10 +08:00
panic.c kernel/panic.c: add missing \n 2017-01-24 16:26:14 -08:00
params.c
pid_namespace.c pid: fix lockdep deadlock warning due to ucount_lock 2017-01-10 13:34:56 +13:00
pid.c
profile.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ptrace.c ptrace: Don't allow accessing an undumpable mm 2016-11-22 12:57:38 -06:00
range.c
reboot.c
relay.c relay: check array offset before using it 2016-12-14 16:04:08 -08:00
resource.c
seccomp.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-12-14 13:57:44 -08:00
signal.c signal: protect SIGNAL_UNKILLABLE from unintentional clearing. 2017-01-10 18:31:55 -08:00
smp.c kernel/smp: Tell the user we're bringing up secondary CPUs 2016-10-26 12:02:35 +02:00
smpboot.c kthread/smpboot: do not park in kthread_create_on_cpu() 2016-10-11 15:06:33 -07:00
smpboot.h
softirq.c softirq: Display IRQ_POLL for irq-poll statistics 2016-10-21 15:45:47 -06:00
stacktrace.c
stop_machine.c locking/core, stop_machine: Yield the CPU during stop machine() 2016-11-16 10:15:09 +01:00
sys_ni.c move aio compat to fs/aio.c 2016-12-22 22:58:37 -05:00
sys.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sysctl_binary.c sysctl: add KERN_CONT to deprecated_sysctl_warning() 2016-12-14 16:04:07 -08:00
sysctl.c sysctl: fix proc_doulongvec_ms_jiffies_minmax() 2017-01-26 09:21:24 -08:00
task_work.c task_work: use READ_ONCE/lockless_dereference, avoid pi_lock if !task_works 2016-08-02 19:35:02 -04:00
taskstats.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-15 10:54:36 -05:00
test_kprobes.c
torture.c torture: Convert torture_shutdown() to hrtimer 2016-08-22 10:01:49 -07:00
tracepoint.c tracing: Have the reg function allow to fail 2016-12-09 09:13:30 -05:00
tsacct.c
ucount.c userns: Make ucounts lock irq-safe 2017-01-24 06:23:51 +13:00
uid16.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
up.c smp: Add function to execute a function synchronously on a CPU 2016-09-05 13:52:39 +02:00
user_namespace.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
user-return-notifier.c
user.c
utsname_sysctl.c
utsname.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
watchdog_hld.c kernel/watchdog: prevent false hardlockup on overloaded system 2017-01-24 16:26:14 -08:00
watchdog.c kernel/watchdog: prevent false hardlockup on overloaded system 2017-01-24 16:26:14 -08:00
workqueue_internal.h
workqueue.c Merge branch 'for-4.9' into for-4.10 2016-10-19 12:12:40 -04:00