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ftrace: trace irq disabled critical timings

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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>
This commit is contained in:
Steven Rostedt
2008-05-12 21:20:42 +02:00
committed by Thomas Gleixner
parent 352ad25aa4
commit 81d68a96a3
13 changed files with 531 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/kernel/process_64.c
View File

@@ -165,7 +165,10 @@ void cpu_idle(void)
*/
local_irq_disable();
enter_idle();
/* Don't trace irqs off for idle */
stop_critical_timings();
idle();
start_critical_timings();
/* In many cases the interrupt that ended idle
has already called exit_idle. But some idle
loops can be woken up without interrupt. */

1
arch/x86/lib/Makefile
View File

@@ -5,6 +5,7 @@
obj-$(CONFIG_SMP) := msr-on-cpu.o
lib-y := delay_$(BITS).o
lib-y += thunk_$(BITS).o
lib-y += usercopy_$(BITS).o getuser_$(BITS).o putuser_$(BITS).o
lib-y += memcpy_$(BITS).o

47
arch/x86/lib/thunk_32.S Normal file
View File

@@ -0,0 +1,47 @@
/*
* Trampoline to trace irqs off. (otherwise CALLER_ADDR1 might crash)
* Copyright 2008 by Steven Rostedt, Red Hat, Inc
* (inspired by Andi Kleen's thunk_64.S)
* Subject to the GNU public license, v.2. No warranty of any kind.
*/
#include <linux/linkage.h>
#define ARCH_TRACE_IRQS_ON \
pushl %eax; \
pushl %ecx; \
pushl %edx; \
call trace_hardirqs_on; \
popl %edx; \
popl %ecx; \
popl %eax;
#define ARCH_TRACE_IRQS_OFF \
pushl %eax; \
pushl %ecx; \
pushl %edx; \
call trace_hardirqs_off; \
popl %edx; \
popl %ecx; \
popl %eax;
#ifdef CONFIG_TRACE_IRQFLAGS
/* put return address in eax (arg1) */
.macro thunk_ra name,func
.globl \name
\name:
pushl %eax
pushl %ecx
pushl %edx
/* Place EIP in the arg1 */
movl 3*4(%esp), %eax
call \func
popl %edx
popl %ecx
popl %eax
ret
.endm
thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
#endif

19
arch/x86/lib/thunk_64.S
View File

@@ -2,6 +2,7 @@
* Save registers before calling assembly functions. This avoids
* disturbance of register allocation in some inline assembly constructs.
* Copyright 2001,2002 by Andi Kleen, SuSE Labs.
* Added trace_hardirqs callers - Copyright 2007 Steven Rostedt, Red Hat, Inc.
* Subject to the GNU public license, v.2. No warranty of any kind.
*/
@@ -42,8 +43,22 @@
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
thunk trace_hardirqs_on_thunk,trace_hardirqs_on
thunk trace_hardirqs_off_thunk,trace_hardirqs_off
/* put return address in rdi (arg1) */
.macro thunk_ra name,func
.globl \name
\name:
CFI_STARTPROC
SAVE_ARGS
/* SAVE_ARGS pushs 9 elements */
/* the next element would be the rip */
movq 9*8(%rsp), %rdi
call \func
jmp restore
CFI_ENDPROC
.endm
thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOC