81d68a96a3
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>
105 lines
3.4 KiB
C
105 lines
3.4 KiB
C
/*
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* include/linux/irqflags.h
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*
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* IRQ flags tracing: follow the state of the hardirq and softirq flags and
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* provide callbacks for transitions between ON and OFF states.
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*
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* This file gets included from lowlevel asm headers too, to provide
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* wrapped versions of the local_irq_*() APIs, based on the
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* raw_local_irq_*() macros from the lowlevel headers.
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*/
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#ifndef _LINUX_TRACE_IRQFLAGS_H
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#define _LINUX_TRACE_IRQFLAGS_H
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#ifdef CONFIG_TRACE_IRQFLAGS
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extern void trace_softirqs_on(unsigned long ip);
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extern void trace_softirqs_off(unsigned long ip);
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extern void trace_hardirqs_on(void);
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extern void trace_hardirqs_off(void);
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# define trace_hardirq_context(p) ((p)->hardirq_context)
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# define trace_softirq_context(p) ((p)->softirq_context)
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# define trace_hardirqs_enabled(p) ((p)->hardirqs_enabled)
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# define trace_softirqs_enabled(p) ((p)->softirqs_enabled)
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# define trace_hardirq_enter() do { current->hardirq_context++; } while (0)
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# define trace_hardirq_exit() do { current->hardirq_context--; } while (0)
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# define trace_softirq_enter() do { current->softirq_context++; } while (0)
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# define trace_softirq_exit() do { current->softirq_context--; } while (0)
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# define INIT_TRACE_IRQFLAGS .softirqs_enabled = 1,
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#else
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# define trace_hardirqs_on() do { } while (0)
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# define trace_hardirqs_off() do { } while (0)
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# define trace_softirqs_on(ip) do { } while (0)
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# define trace_softirqs_off(ip) do { } while (0)
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# define trace_hardirq_context(p) 0
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# define trace_softirq_context(p) 0
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# define trace_hardirqs_enabled(p) 0
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# define trace_softirqs_enabled(p) 0
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# define trace_hardirq_enter() do { } while (0)
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# define trace_hardirq_exit() do { } while (0)
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# define trace_softirq_enter() do { } while (0)
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# define trace_softirq_exit() do { } while (0)
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# define INIT_TRACE_IRQFLAGS
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#endif
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#ifdef CONFIG_IRQSOFF_TRACER
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extern void stop_critical_timings(void);
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extern void start_critical_timings(void);
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#else
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# define stop_critical_timings() do { } while (0)
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# define start_critical_timings() do { } while (0)
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#endif
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#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
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#include <asm/irqflags.h>
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#define local_irq_enable() \
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do { trace_hardirqs_on(); raw_local_irq_enable(); } while (0)
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#define local_irq_disable() \
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do { raw_local_irq_disable(); trace_hardirqs_off(); } while (0)
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#define local_irq_save(flags) \
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do { raw_local_irq_save(flags); trace_hardirqs_off(); } while (0)
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#define local_irq_restore(flags) \
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do { \
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if (raw_irqs_disabled_flags(flags)) { \
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raw_local_irq_restore(flags); \
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trace_hardirqs_off(); \
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} else { \
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trace_hardirqs_on(); \
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raw_local_irq_restore(flags); \
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} \
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} while (0)
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#else /* !CONFIG_TRACE_IRQFLAGS_SUPPORT */
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/*
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* The local_irq_*() APIs are equal to the raw_local_irq*()
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* if !TRACE_IRQFLAGS.
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*/
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# define raw_local_irq_disable() local_irq_disable()
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# define raw_local_irq_enable() local_irq_enable()
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# define raw_local_irq_save(flags) local_irq_save(flags)
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# define raw_local_irq_restore(flags) local_irq_restore(flags)
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#endif /* CONFIG_TRACE_IRQFLAGS_SUPPORT */
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#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
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#define safe_halt() \
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do { \
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trace_hardirqs_on(); \
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raw_safe_halt(); \
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} while (0)
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#define local_save_flags(flags) raw_local_save_flags(flags)
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#define irqs_disabled() \
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({ \
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unsigned long _flags; \
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\
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raw_local_save_flags(_flags); \
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raw_irqs_disabled_flags(_flags); \
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})
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#define irqs_disabled_flags(flags) raw_irqs_disabled_flags(flags)
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#endif /* CONFIG_X86 */
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#endif
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