linux/arch/x86/lib
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
..
checksum_32.S
clear_page_64.S
copy_page_64.S
copy_user_64.S
copy_user_nocache_64.S x86: fence oostores on 64-bit 2007-10-12 18:41:21 -07:00
csum-copy_64.S
csum-partial_64.c x86: fix csum_partial() export 2008-05-13 19:38:47 +02:00
csum-wrappers_64.c x86: clean up csum-wrappers_64.c some more 2008-02-19 16:18:32 +01:00
delay_32.c read_current_timer() cleanups 2008-02-06 10:41:02 -08:00
delay_64.c read_current_timer() cleanups 2008-02-06 10:41:02 -08:00
getuser_32.S
getuser_64.S
io_64.c x86: coding style fixes in arch/x86/lib/io_64.c 2008-02-19 16:18:32 +01:00
iomap_copy_64.S
Makefile ftrace: trace irq disabled critical timings 2008-05-23 20:32:46 +02:00
memcpy_32.c x86: coding style fixes to arch/x86/lib/memcpy_32.c 2008-04-17 17:40:49 +02:00
memcpy_64.S
memmove_64.c x86: coding style fixes to arch/x86/lib/memmove_64.c 2008-04-17 17:40:48 +02:00
memset_64.S
mmx_32.c x86: clean up mmx_32.c 2008-04-17 17:40:47 +02:00
msr-on-cpu.c i386: simplify smp_call_function_single() call sequence in msr-on-cpu 2007-10-17 20:16:20 +02:00
putuser_32.S
putuser_64.S
rwlock_64.S x86: rename .i assembler includes to .h 2007-10-17 20:16:29 +02:00
semaphore_32.S Generic semaphore implementation 2008-04-17 10:42:34 -04:00
string_32.c x86: coding style fixes to arch/x86/lib/string_32.c 2008-04-17 17:40:48 +02:00
strstr_32.c x86: coding style fixes to arch/x86/lib/strstr_3 2008-04-17 17:40:49 +02:00
thunk_32.S ftrace: trace irq disabled critical timings 2008-05-23 20:32:46 +02:00
thunk_64.S ftrace: trace irq disabled critical timings 2008-05-23 20:32:46 +02:00
usercopy_32.c x86: coding style fixes to arch/x86/lib/usercopy_32.c 2008-04-17 17:40:51 +02:00
usercopy_64.c x86: use _ASM_EXTABLE macro in arch/x86/lib/usercopy_64.c 2008-02-04 16:47:57 +01:00