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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>
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|---|---|---|
| .. | ||
| acpi | ||
| cpu | ||
| .gitignore | ||
| alternative.c | ||
| aperture_64.c | ||
| apic_32.c | ||
| apic_64.c | ||
| apm_32.c | ||
| asm-offsets.c | ||
| asm-offsets_32.c | ||
| asm-offsets_64.c | ||
| audit_64.c | ||
| bootflag.c | ||
| bugs_64.c | ||
| cpuid.c | ||
| crash.c | ||
| crash_dump_32.c | ||
| crash_dump_64.c | ||
| doublefault_32.c | ||
| ds.c | ||
| e820_32.c | ||
| e820_64.c | ||
| early-quirks.c | ||
| early_printk.c | ||
| efi.c | ||
| efi_32.c | ||
| efi_64.c | ||
| efi_stub_32.S | ||
| efi_stub_64.S | ||
| entry_32.S | ||
| entry_64.S | ||
| genapic_64.c | ||
| genapic_flat_64.c | ||
| genx2apic_uv_x.c | ||
| geode_32.c | ||
| head32.c | ||
| head64.c | ||
| head_32.S | ||
| head_64.S | ||
| hpet.c | ||
| i386_ksyms_32.c | ||
| i387.c | ||
| i8237.c | ||
| i8253.c | ||
| i8259_32.c | ||
| i8259_64.c | ||
| init_task.c | ||
| io_apic_32.c | ||
| io_apic_64.c | ||
| io_delay.c | ||
| ioport.c | ||
| ipi.c | ||
| irq_32.c | ||
| irq_64.c | ||
| k8.c | ||
| kdebugfs.c | ||
| kgdb.c | ||
| kprobes.c | ||
| kvm.c | ||
| kvmclock.c | ||
| ldt.c | ||
| machine_kexec_32.c | ||
| machine_kexec_64.c | ||
| Makefile | ||
| mca_32.c | ||
| mfgpt_32.c | ||
| microcode.c | ||
| mmconf-fam10h_64.c | ||
| module_32.c | ||
| module_64.c | ||
| mpparse.c | ||
| msr.c | ||
| nmi_32.c | ||
| nmi_64.c | ||
| numaq_32.c | ||
| olpc.c | ||
| paravirt.c | ||
| paravirt_patch_32.c | ||
| paravirt_patch_64.c | ||
| pci-calgary_64.c | ||
| pci-dma.c | ||
| pci-gart_64.c | ||
| pci-nommu.c | ||
| pci-swiotlb_64.c | ||
| pcspeaker.c | ||
| pmtimer_64.c | ||
| process.c | ||
| process_32.c | ||
| process_64.c | ||
| ptrace.c | ||
| quirks.c | ||
| reboot.c | ||
| reboot_fixups_32.c | ||
| relocate_kernel_32.S | ||
| relocate_kernel_64.S | ||
| rtc.c | ||
| scx200_32.c | ||
| setup.c | ||
| setup64.c | ||
| setup_32.c | ||
| setup_64.c | ||
| sigframe.h | ||
| signal_32.c | ||
| signal_64.c | ||
| smp.c | ||
| smpboot.c | ||
| smpcommon.c | ||
| smpcommon_32.c | ||
| srat_32.c | ||
| stacktrace.c | ||
| step.c | ||
| summit_32.c | ||
| sys_i386_32.c | ||
| sys_x86_64.c | ||
| syscall_64.c | ||
| syscall_table_32.S | ||
| tce_64.c | ||
| test_nx.c | ||
| test_rodata.c | ||
| time_32.c | ||
| time_64.c | ||
| tlb_32.c | ||
| tlb_64.c | ||
| tls.c | ||
| tls.h | ||
| topology.c | ||
| trampoline.c | ||
| trampoline_32.S | ||
| trampoline_64.S | ||
| traps_32.c | ||
| traps_64.c | ||
| tsc_32.c | ||
| tsc_64.c | ||
| tsc_sync.c | ||
| verify_cpu_64.S | ||
| vm86_32.c | ||
| vmi_32.c | ||
| vmiclock_32.c | ||
| vmlinux.lds.S | ||
| vmlinux_32.lds.S | ||
| vmlinux_64.lds.S | ||
| vsmp_64.c | ||
| vsyscall_64.c | ||
| x8664_ksyms_64.c | ||