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Martin KaFai Lau a7636d9ecf kprobes: Optimize hot path by using percpu counter to collect 'nhit' statistics 
When doing ebpf+kprobe on some hot TCP functions (e.g.
tcp_rcv_established), the kprobe_dispatcher() function
shows up in 'perf report'.

In kprobe_dispatcher(), there is a lot of cache bouncing
on 'tk->nhit++'.  'tk->nhit' and 'tk->tp.flags' also share
the same cacheline.

perf report (cycles:pp):

	8.30%  ipv4_dst_check
	4.74%  copy_user_enhanced_fast_string
	3.93%  dst_release
	2.80%  tcp_v4_rcv
	2.31%  queued_spin_lock_slowpath
	2.30%  _raw_spin_lock
	1.88%  mlx4_en_process_rx_cq
	1.84%  eth_get_headlen
	1.81%  ip_rcv_finish
	~~~~
	1.71%  kprobe_dispatcher
	~~~~
	1.55%  mlx4_en_xmit
	1.09%  __probe_kernel_read

perf report after patch:

	9.15%  ipv4_dst_check
	5.00%  copy_user_enhanced_fast_string
	4.12%  dst_release
	2.96%  tcp_v4_rcv
	2.50%  _raw_spin_lock
	2.39%  queued_spin_lock_slowpath
	2.11%  eth_get_headlen
	2.03%  mlx4_en_process_rx_cq
	1.69%  mlx4_en_xmit
	1.19%  ip_rcv_finish
	1.12%  __probe_kernel_read
	1.02%  ehci_hcd_cleanup

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Kernel Team <kernel-team@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1454531308-2441898-1-git-send-email-kafai@fb.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 		2016-02-09 11:08:58 +01:00
..
bpf perf/bpf: Convert perf_event_array to use struct file 2016-01-29 08:35:25 +01:00
configs kconfig: add xenconfig defconfig helper 2015-06-16 11:04:29 +01:00
debug module: use a structure to encapsulate layout. 2015-12-04 22:46:25 +01:00
events Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-31 15:38:27 -08:00
gcov gcov: use within_module() helper. 2015-12-04 22:46:25 +01:00
irq Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-31 14:48:58 -08:00
livepatch livepatch: Cleanup module page permission changes 2015-12-04 22:51:07 +01:00
locking rtmutex: Make wait_lock irq safe 2016-01-26 11:08:35 +01:00
power PM: APM_EMULATION does not depend on PM 2016-01-27 23:20:14 +01:00
printk kernel: printk: specify alignment for struct printk_log 2016-01-20 17:09:18 -08:00
rcu Merge branches 'doc.2015.12.05a', 'exp.2015.12.07a', 'fixes.2015.12.07a', 'list.2015.12.04b' and 'torture.2015.12.05a' into HEAD 2015-12-07 17:02:54 -08:00
sched Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-31 15:44:04 -08:00
time Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-31 15:49:06 -08:00
trace kprobes: Optimize hot path by using percpu counter to collect 'nhit' statistics 2016-02-09 11:08:58 +01:00
.gitignore certs: add .gitignore to stop git nagging about x509_certificate_list 2015-10-21 15:18:35 +01:00
Kconfig.freezer
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Kconfig.hz
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Kconfig.locks locking/qrwlock: Rename QUEUE_RWLOCK to QUEUED_RWLOCKS 2015-05-12 09:46:00 +02:00
Kconfig.preempt
…
Makefile sys_membarrier(): system-wide memory barrier (generic, x86) 2015-09-11 15:21:34 -07:00
acct.c
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async.c async: export current_is_async() 2015-11-19 17:51:48 +01:00
audit.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-01-17 19:13:15 -08:00
audit.h security: Make inode argument of inode_getsecid non-const 2015-12-24 11:09:39 -05:00
audit_fsnotify.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
audit_tree.c audit: audit_tree_match can be boolean 2015-11-04 08:23:51 -05:00
audit_watch.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
auditfilter.c audit: fix comment block whitespace 2015-11-04 08:23:51 -05:00
auditsc.c security: Make inode argument of inode_getsecid non-const 2015-12-24 11:09:39 -05:00
backtracetest.c
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bounds.c
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capability.c
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cgroup.c Merge branch 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2016-01-12 19:20:32 -08:00
cgroup_freezer.c cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friends 2015-12-03 10:24:08 -05:00
cgroup_pids.c cgroup_pids: fix a typo. 2015-12-14 14:54:37 -05:00
compat.c compat: cleanup coding in compat_get_bitmap() and compat_put_bitmap() 2015-06-04 23:57:18 +02:00
configs.c
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context_tracking.c context_tracking: Switch to new static_branch API 2015-11-24 09:56:43 +01:00
cpu.c kernel/cpu.c: make set_cpu_* static inlines 2016-01-20 17:09:18 -08:00
cpu_pm.c kernel/cpu_pm: fix cpu_cluster_pm_exit comment 2015-09-03 02:42:20 +02:00
cpuset.c Merge branch 'for-4.4-fixes' into for-4.5 2015-12-03 10:22:52 -05:00
crash_dump.c
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cred.c kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
delayacct.c kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
dma.c
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elfcore.c
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exec_domain.c
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exit.c exit: remove unneeded declaration of exit_mm() 2016-01-20 17:09:18 -08:00
extable.c kernel/extable.c: remove duplicated include 2015-09-10 13:29:01 -07:00
fork.c mm: rework virtual memory accounting 2016-01-14 16:00:49 -08:00
freezer.c
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futex.c rtmutex: Make wait_lock irq safe 2016-01-26 11:08:35 +01:00
futex_compat.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-01-20 17:09:18 -08:00
groups.c
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hung_task.c
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irq_work.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
jump_label.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
kallsyms.c
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kcmp.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-01-20 17:09:18 -08:00
kexec.c kexec: set KEXEC_TYPE_CRASH before sanity_check_segment_list() 2016-01-20 17:09:18 -08:00
kexec_core.c kernel/kexec_core.c: use list_for_each_entry_safe in kimage_free_page_list 2016-01-20 17:09:18 -08:00
kexec_file.c kexec: move some memembers and definitions within the scope of CONFIG_KEXEC_FILE 2016-01-20 17:09:18 -08:00
kexec_internal.h kexec: move some memembers and definitions within the scope of CONFIG_KEXEC_FILE 2016-01-20 17:09:18 -08:00
kmod.c kmod: don't run async usermode helper as a child of kworker thread 2015-10-23 17:55:10 +09:00
kprobes.c perf/x86/hw_breakpoints: Disallow kernel breakpoints unless kprobe-safe 2015-08-04 10:16:54 +02:00
ksysfs.c rcu: Remove TINY_RCU bloat from pointless boot parameters 2015-12-07 16:59:37 -08:00
kthread.c kernel/kthread.c:kthread_create_on_node(): clarify documentation 2015-09-04 16:54:41 -07:00
latencytop.c
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membarrier.c sys_membarrier(): system-wide memory barrier (generic, x86) 2015-09-11 15:21:34 -07:00
memremap.c phys_to_pfn_t: use phys_addr_t 2016-01-31 09:10:19 -08:00
module-internal.h
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module.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2016-01-14 16:38:02 -08:00
module_signing.c KEYS: Merge the type-specific data with the payload data 2015-10-21 15:18:36 +01:00
notifier.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 08:40:25 -07:00
nsproxy.c
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padata.c
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panic.c printk: do cond_resched() between lines while outputting to consoles 2016-01-16 11:17:25 -08:00
params.c Nothing exciting, minor tweaks and cleanups. 2015-11-09 15:53:39 -08:00
pid.c Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-31 15:44:04 -08:00
pid_namespace.c
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profile.c mm: rename alloc_pages_exact_node() to __alloc_pages_node() 2015-09-08 15:35:28 -07:00
ptrace.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-01-20 17:09:18 -08:00
range.c
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reboot.c kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
relay.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
resource.c restrict /dev/mem to idle io memory ranges 2016-01-09 06:30:49 -08:00
seccomp.c seccomp: always propagate NO_NEW_PRIVS on tsync 2016-01-27 07:38:25 -08:00
signal.c kernel/signal.c: unexport sigsuspend() 2015-11-20 16:17:32 -08:00
smp.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
smpboot.c stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark() 2015-10-20 10:23:55 +02:00
smpboot.h
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softirq.c
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stacktrace.c
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stop_machine.c kernel/stop_machine.c: remove CONFIG_SMP dependencies 2016-01-16 11:17:24 -08:00
sys.c prctl: take mmap sem for writing to protect against others 2016-01-20 17:09:18 -08:00
sys_ni.c vfs: add copy_file_range syscall and vfs helper 2015-12-01 14:00:53 -05:00
sysctl.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-01-22 10:24:03 -08:00
sysctl_binary.c
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task_work.c task_work: remove fifo ordering guarantee 2015-09-05 13:46:58 -07:00
taskstats.c
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test_kprobes.c
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torture.c torture: Consolidate cond_resched_rcu_qs() into stutter_wait() 2015-10-06 11:25:01 -07:00
tracepoint.c tracepoint: Give priority to probes of tracepoints 2015-10-25 21:33:54 -04:00
tsacct.c
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uid16.c
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up.c
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user-return-notifier.c
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user.c
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user_namespace.c kernel/*: switch to memdup_user_nul() 2016-01-04 10:27:55 -05:00
utsname.c
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utsname_sysctl.c
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watchdog.c Merge branch 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2016-01-11 18:53:13 -08:00
workqueue.c workqueue: simplify the apply_workqueue_attrs_locked() 2016-01-07 11:04:34 -05:00
workqueue_internal.h
…