Merge branch 'tip/perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into perf/core
This commit is contained in:
Ingo Molnar
@@ -247,6 +247,13 @@ You need very few things to get the syscalls tracing in an arch.
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- Support the TIF_SYSCALL_TRACEPOINT thread flags.
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- Put the trace_sys_enter() and trace_sys_exit() tracepoints calls from ptrace
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in the ptrace syscalls tracing path.
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- If the system call table on this arch is more complicated than a simple array
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of addresses of the system calls, implement an arch_syscall_addr to return
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the address of a given system call.
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- If the symbol names of the system calls do not match the function names on
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this arch, define ARCH_HAS_SYSCALL_MATCH_SYM_NAME in asm/ftrace.h and
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implement arch_syscall_match_sym_name with the appropriate logic to return
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true if the function name corresponds with the symbol name.
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- Tag this arch as HAVE_SYSCALL_TRACEPOINTS.
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@@ -80,11 +80,11 @@ of ftrace. Here is a list of some of the key files:
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tracers listed here can be configured by
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echoing their name into current_tracer.
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tracing_enabled:
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tracing_on:
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This sets or displays whether the current_tracer
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is activated and tracing or not. Echo 0 into this
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file to disable the tracer or 1 to enable it.
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This sets or displays whether writing to the trace
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ring buffer is enabled. Echo 0 into this file to disable
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the tracer or 1 to enable it.
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trace:
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@@ -202,10 +202,6 @@ Here is the list of current tracers that may be configured.
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to draw a graph of function calls similar to C code
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source.
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"sched_switch"
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Traces the context switches and wakeups between tasks.
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"irqsoff"
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Traces the areas that disable interrupts and saves
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@@ -273,39 +269,6 @@ format, the function name that was traced "path_put" and the
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parent function that called this function "path_walk". The
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timestamp is the time at which the function was entered.
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The sched_switch tracer also includes tracing of task wakeups
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and context switches.
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ksoftirqd/1-7 [01] 1453.070013: 7:115:R + 2916:115:S
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ksoftirqd/1-7 [01] 1453.070013: 7:115:R + 10:115:S
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ksoftirqd/1-7 [01] 1453.070013: 7:115:R ==> 10:115:R
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events/1-10 [01] 1453.070013: 10:115:S ==> 2916:115:R
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kondemand/1-2916 [01] 1453.070013: 2916:115:S ==> 7:115:R
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ksoftirqd/1-7 [01] 1453.070013: 7:115:S ==> 0:140:R
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Wake ups are represented by a "+" and the context switches are
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shown as "==>". The format is:
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Context switches:
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Previous task Next Task
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<pid>:<prio>:<state> ==> <pid>:<prio>:<state>
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Wake ups:
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Current task Task waking up
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<pid>:<prio>:<state> + <pid>:<prio>:<state>
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The prio is the internal kernel priority, which is the inverse
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of the priority that is usually displayed by user-space tools.
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Zero represents the highest priority (99). Prio 100 starts the
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"nice" priorities with 100 being equal to nice -20 and 139 being
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nice 19. The prio "140" is reserved for the idle task which is
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the lowest priority thread (pid 0).
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Latency trace format
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--------------------
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@@ -491,79 +454,6 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
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latencies, as described in "Latency
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trace format".
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sched_switch
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------------
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This tracer simply records schedule switches. Here is an example
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of how to use it.
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# echo sched_switch > current_tracer
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# echo 1 > tracing_enabled
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# sleep 1
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# echo 0 > tracing_enabled
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# cat trace
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# tracer: sched_switch
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#
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# TASK-PID CPU# TIMESTAMP FUNCTION
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# | | | | |
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bash-3997 [01] 240.132281: 3997:120:R + 4055:120:R
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bash-3997 [01] 240.132284: 3997:120:R ==> 4055:120:R
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sleep-4055 [01] 240.132371: 4055:120:S ==> 3997:120:R
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bash-3997 [01] 240.132454: 3997:120:R + 4055:120:S
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bash-3997 [01] 240.132457: 3997:120:R ==> 4055:120:R
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sleep-4055 [01] 240.132460: 4055:120:D ==> 3997:120:R
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bash-3997 [01] 240.132463: 3997:120:R + 4055:120:D
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bash-3997 [01] 240.132465: 3997:120:R ==> 4055:120:R
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<idle>-0 [00] 240.132589: 0:140:R + 4:115:S
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<idle>-0 [00] 240.132591: 0:140:R ==> 4:115:R
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ksoftirqd/0-4 [00] 240.132595: 4:115:S ==> 0:140:R
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<idle>-0 [00] 240.132598: 0:140:R + 4:115:S
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<idle>-0 [00] 240.132599: 0:140:R ==> 4:115:R
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ksoftirqd/0-4 [00] 240.132603: 4:115:S ==> 0:140:R
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sleep-4055 [01] 240.133058: 4055:120:S ==> 3997:120:R
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[...]
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As we have discussed previously about this format, the header
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shows the name of the trace and points to the options. The
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"FUNCTION" is a misnomer since here it represents the wake ups
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and context switches.
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The sched_switch file only lists the wake ups (represented with
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'+') and context switches ('==>') with the previous task or
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current task first followed by the next task or task waking up.
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The format for both of these is PID:KERNEL-PRIO:TASK-STATE.
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Remember that the KERNEL-PRIO is the inverse of the actual
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priority with zero (0) being the highest priority and the nice
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values starting at 100 (nice -20). Below is a quick chart to map
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the kernel priority to user land priorities.
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Kernel Space User Space
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===============================================================
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0(high) to 98(low) user RT priority 99(high) to 1(low)
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with SCHED_RR or SCHED_FIFO
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---------------------------------------------------------------
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99 sched_priority is not used in scheduling
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decisions(it must be specified as 0)
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---------------------------------------------------------------
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100(high) to 139(low) user nice -20(high) to 19(low)
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---------------------------------------------------------------
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140 idle task priority
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---------------------------------------------------------------
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The task states are:
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R - running : wants to run, may not actually be running
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S - sleep : process is waiting to be woken up (handles signals)
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D - disk sleep (uninterruptible sleep) : process must be woken up
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(ignores signals)
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T - stopped : process suspended
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t - traced : process is being traced (with something like gdb)
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Z - zombie : process waiting to be cleaned up
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X - unknown
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ftrace_enabled
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--------------
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@@ -607,10 +497,10 @@ an example:
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# echo irqsoff > current_tracer
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# echo latency-format > trace_options
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# echo 0 > tracing_max_latency
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# echo 1 > tracing_enabled
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# echo 1 > tracing_on
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# ls -ltr
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[...]
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# echo 0 > tracing_enabled
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# echo 0 > tracing_on
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# cat trace
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# tracer: irqsoff
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#
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@@ -715,10 +605,10 @@ is much like the irqsoff tracer.
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# echo preemptoff > current_tracer
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# echo latency-format > trace_options
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# echo 0 > tracing_max_latency
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# echo 1 > tracing_enabled
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# echo 1 > tracing_on
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# ls -ltr
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[...]
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# echo 0 > tracing_enabled
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# echo 0 > tracing_on
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# cat trace
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# tracer: preemptoff
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#
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@@ -863,10 +753,10 @@ tracers.
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# echo preemptirqsoff > current_tracer
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# echo latency-format > trace_options
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# echo 0 > tracing_max_latency
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# echo 1 > tracing_enabled
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# echo 1 > tracing_on
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# ls -ltr
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[...]
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# echo 0 > tracing_enabled
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# echo 0 > tracing_on
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# cat trace
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# tracer: preemptirqsoff
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#
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@@ -1026,9 +916,9 @@ Instead of performing an 'ls', we will run 'sleep 1' under
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# echo wakeup > current_tracer
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# echo latency-format > trace_options
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# echo 0 > tracing_max_latency
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# echo 1 > tracing_enabled
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# echo 1 > tracing_on
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# chrt -f 5 sleep 1
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# echo 0 > tracing_enabled
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# echo 0 > tracing_on
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# cat trace
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# tracer: wakeup
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#
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@@ -1140,9 +1030,9 @@ ftrace_enabled is set; otherwise this tracer is a nop.
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# sysctl kernel.ftrace_enabled=1
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# echo function > current_tracer
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# echo 1 > tracing_enabled
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# echo 1 > tracing_on
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# usleep 1
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# echo 0 > tracing_enabled
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# echo 0 > tracing_on
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# cat trace
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# tracer: function
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#
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@@ -1180,7 +1070,7 @@ int trace_fd;
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[...]
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int main(int argc, char *argv[]) {
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[...]
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trace_fd = open(tracing_file("tracing_enabled"), O_WRONLY);
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trace_fd = open(tracing_file("tracing_on"), O_WRONLY);
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[...]
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if (condition_hit()) {
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write(trace_fd, "0", 1);
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@@ -1631,9 +1521,9 @@ If I am only interested in sys_nanosleep and hrtimer_interrupt:
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# echo sys_nanosleep hrtimer_interrupt \
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> set_ftrace_filter
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# echo function > current_tracer
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# echo 1 > tracing_enabled
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# echo 1 > tracing_on
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# usleep 1
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# echo 0 > tracing_enabled
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# echo 0 > tracing_on
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# cat trace
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# tracer: ftrace
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#
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@@ -1879,9 +1769,9 @@ different. The trace is live.
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# echo function > current_tracer
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# cat trace_pipe > /tmp/trace.out &
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[1] 4153
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# echo 1 > tracing_enabled
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# echo 1 > tracing_on
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# usleep 1
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# echo 0 > tracing_enabled
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# echo 0 > tracing_on
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# cat trace
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# tracer: function
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#
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