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Steven Rostedt 81d68a96a3 ftrace: trace irq disabled critical timings 
This patch adds latency tracing for critical timings
(how long interrupts are disabled for).

 "irqsoff" is added to /debugfs/tracing/available_tracers

Note:
  tracing_max_latency
    also holds the max latency for irqsoff (in usecs).
   (default to large number so one must start latency tracing)

  tracing_thresh
    threshold (in usecs) to always print out if irqs off
    is detected to be longer than stated here.
    If irq_thresh is non-zero, then max_irq_latency
    is ignored.

Here's an example of a trace with ftrace_enabled = 0

=======
preemption latency trace v1.1.5 on 2.6.24-rc7
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------
 latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
    -----------------
    | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
    -----------------
 => started at: _spin_lock_irqsave+0x2a/0xb7
 => ended at:   _spin_unlock_irqrestore+0x32/0x5f

                 _------=> CPU#
                / _-----=> irqs-off
               | / _----=> need-resched
               || / _---=> hardirq/softirq
               ||| / _--=> preempt-depth
               |||| /
               |||||     delay
   cmd     pid ||||| time  |   caller
      \   /    |||||   \   |   /
 swapper-0     1d.s3    0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000])
 swapper-0     1d.s3  100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000])
 swapper-0     1d.s3  100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f)

vim:ft=help
=======

And this is a trace with ftrace_enabled == 1

=======
preemption latency trace v1.1.5 on 2.6.24-rc7
--------------------------------------------------------------------
 latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
    -----------------
    | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
    -----------------
 => started at: _spin_lock_irqsave+0x2a/0xb7
 => ended at:   _spin_unlock_irqrestore+0x32/0x5f

                 _------=> CPU#
                / _-----=> irqs-off
               | / _----=> need-resched
               || / _---=> hardirq/softirq
               ||| / _--=> preempt-depth
               |||| /
               |||||     delay
   cmd     pid ||||| time  |   caller
      \   /    |||||   \   |   /
 swapper-0     1dNs3    0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000])
 swapper-0     1dNs3   46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000])
 swapper-0     1dNs3   46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000])
 swapper-0     1dNs3   46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000])
 swapper-0     1dNs3   47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000])
 swapper-0     1dNs3   47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47)
 swapper-0     1dNs3   97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50)
 swapper-0     1dNs3   98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000])
 swapper-0     1dNs3   99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000])
 swapper-0     1dNs3  101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000])
 swapper-0     1dNs3  102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000])
 swapper-0     1dNs3  102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f)

vim:ft=help
=======

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
 		2008-05-23 20:32:46 +02:00
..
irq genirq: reenable a nobody cared disabled irq when a new driver arrives 2008-05-02 13:40:34 +02:00
power Merge branches 'release', 'acpica', 'bugzilla-10224', 'bugzilla-9772', 'bugzilla-9916', 'ec', 'eeepc', 'idle', 'misc', 'pm-legacy', 'sysfs-links-2.6.26', 'thermal', 'thinkpad' and 'video' into release 2008-04-30 13:58:00 -04:00
time clocksource: allow read access to available/current_clocksource 2008-05-03 18:11:48 +02:00
trace ftrace: trace irq disabled critical timings 2008-05-23 20:32:46 +02:00
.gitignore
…
Kconfig.hz
…
Kconfig.preempt
…
Makefile ftrace: latency tracer infrastructure 2008-05-23 20:32:06 +02:00
acct.c
…
audit.c [patch 1/1] audit_send_reply(): fix error-path memory leak 2008-05-17 03:30:22 -04:00
audit.h
…
audit_tree.c [PATCH] list_for_each_rcu must die: audit 2008-05-17 03:30:23 -04:00
auditfilter.c
…
auditsc.c
…
backtracetest.c
…
bounds.c
…
capability.c
…
cgroup.c mm: bdi: add separate writeback accounting capability 2008-04-30 08:29:50 -07:00
cgroup_debug.c
…
compat.c ntp: support for TAI 2008-05-01 08:03:59 -07:00
configs.c
…
cpu.c kernel: replace remaining __FUNCTION__ occurrences 2008-04-30 08:29:54 -07:00
cpuset.c Fix cpuset sched_relax_domain_level control file 2008-05-08 10:46:56 -07:00
delayacct.c
…
dma.c
…
exec_domain.c
…
exit.c [PATCH] split linux/file.h 2008-05-01 13:08:16 -04:00
extable.c
…
fork.c ftrace: trace irq disabled critical timings 2008-05-23 20:32:46 +02:00
futex.c Removal of FUTEX_FD 2008-05-05 08:18:45 -07:00
futex_compat.c
…
hrtimer.c hrtimer: remove duplicate helper function 2008-05-03 18:11:48 +02:00
itimer.c
…
kallsyms.c
…
kexec.c kexec: make extended crashkernel= syntax less confusing 2008-05-01 08:04:00 -07:00
kfifo.c
…
kgdb.c lib: create common ascii hex array 2008-05-14 19:11:14 -07:00
kmod.c [PATCH] split linux/file.h 2008-05-01 13:08:16 -04:00
kprobes.c
…
ksysfs.c
…
kthread.c Deprecate find_task_by_pid() 2008-04-30 08:29:48 -07:00
latencytop.c
…
lockdep.c ftrace: trace irq disabled critical timings 2008-05-23 20:32:46 +02:00
lockdep_internals.h
…
lockdep_proc.c
…
marker.c make marker_debug static 2008-04-30 08:29:49 -07:00
module.c module: don't ignore vermagic string if module doesn't have modversions 2008-05-09 07:45:18 -07:00
mutex-debug.c
…
mutex-debug.h
…
mutex.c
…
mutex.h
…
notifier.c
…
ns_cgroup.c
…
nsproxy.c
…
panic.c
…
params.c
…
pid.c pids: introduce change_pid() helper 2008-04-30 08:29:48 -07:00
pid_namespace.c pidns: make pid->level and pid_ns->level unsigned 2008-04-30 08:29:49 -07:00
pm_qos_params.c
…
posix-cpu-timers.c remove div_long_long_rem 2008-05-01 08:03:58 -07:00
posix-timers.c signals: join send_sigqueue() with send_group_sigqueue() 2008-04-30 08:29:36 -07:00
printk.c ftrace: trace irq disabled critical timings 2008-05-23 20:32:46 +02:00
profile.c
…
ptrace.c make generic sys_ptrace unconditional 2008-05-01 10:21:54 -07:00
rcuclassic.c
…
rcupdate.c
…
rcupreempt.c
…
rcupreempt_trace.c
…
rcutorture.c
…
relay.c Revert "relay: fix splice problem" 2008-05-08 14:06:19 +02:00
res_counter.c
…
resource.c
…
rtmutex-debug.c
…
rtmutex-debug.h
…
rtmutex-tester.c
…
rtmutex.c
…
rtmutex.h
…
rtmutex_common.h
…
rwsem.c
…
sched.c ftrace: make the task state char-string visible to all 2008-05-23 20:31:05 +02:00
sched_clock.c sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK 2008-05-05 23:56:18 +02:00
sched_debug.c sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK 2008-05-05 23:56:18 +02:00
sched_fair.c sched: fix weight calculations 2008-05-08 17:00:42 +02:00
sched_features.h
…
sched_idletask.c sched: make rt_sched_class, idle_sched_class static 2008-05-05 23:56:17 +02:00
sched_rt.c sched: fix RT task-wakeup logic 2008-05-05 23:56:18 +02:00
sched_stats.h
…
seccomp.c
…
semaphore.c Revert "semaphore: fix" 2008-05-10 20:43:22 -07:00
signal.c signals: add set_restore_sigmask 2008-04-30 08:29:37 -07:00
softirq.c Fix cpu hotplug problem in softirq code 2008-05-01 08:03:58 -07:00
softlockup.c
…
spinlock.c
…
srcu.c
…
stacktrace.c
…
stop_machine.c
…
sys.c pids: sys_getpgid: fix unsafe *pid usage, s/tasklist/rcu/ 2008-04-30 08:29:49 -07:00
sys_ni.c
…
sysctl.c [PATCH] avoid multiplication overflows and signedness issues for max_fds 2008-05-16 17:22:52 -04:00
sysctl_check.c
…
taskstats.c Use find_task_by_vpid in taskstats 2008-04-30 08:29:48 -07:00
test_kprobes.c
…
time.c Make constants in kernel/timeconst.h fixed 64 bits 2008-05-02 16:18:42 -07:00
timeconst.pl Make constants in kernel/timeconst.h fixed 64 bits 2008-05-02 16:18:42 -07:00
timer.c debugobjects: add timer specific object debugging code 2008-04-30 08:29:53 -07:00
tsacct.c
…
uid16.c
…
user.c alloc_uid: cleanup 2008-04-30 08:29:53 -07:00
user_namespace.c
…
utsname.c
…
utsname_sysctl.c
…
wait.c
…
workqueue.c workqueue: remove redundant function invocation 2008-05-01 08:04:02 -07:00