This release cycle is rather small. Just a few fixes to tracing.
The big change is the addition of the hwlat tracer. It not only detects SMIs, but also other latency that's caused by the hardware. I have detected some latency from large boxes having bus contention. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAABAgAGBQJX9a77AAoJEKKk/i67LK/8UPEH/jcqMmOMhQYVQsNaJViA5uJM SV96gaLCc9cxXY04Hf7vx8RkVIyIqTCCQZ+RVZt4RSeqpsB2IzZ1u0CNKs2Z0MTv MdvQJoazRoDgVuPzKAsdAlDd0ykqHEFA5ayF3XDK4P2J97La+B4rQIqEiJX/aDrz i0NQQFg2ZF46mXJXn4oXe6nmr6WnbiEduawVjd7JvgILJO2hojDicOTQlNG41Nys 68fOV8mLk0OL7sFRjySLGcbdbKhP2YbNhxILXl8geLgS9+CFZXkE8oTRjjy9IMNA XrqbFLMWaRVv+Nig7bHIWKE8ZErC5WCYUw4LD2GTLMDx5AkAVLGFFp6TOiO4SG8= =ke23 -----END PGP SIGNATURE----- Merge tag 'trace-v4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "This release cycle is rather small. Just a few fixes to tracing. The big change is the addition of the hwlat tracer. It not only detects SMIs, but also other latency that's caused by the hardware. I have detected some latency from large boxes having bus contention" * tag 'trace-v4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Call traceoff trigger after event is recorded ftrace/scripts: Add helper script to bisect function tracing problem functions tracing: Have max_latency be defined for HWLAT_TRACER as well tracing: Add NMI tracing in hwlat detector tracing: Have hwlat trace migrate across tracing_cpumask CPUs tracing: Add documentation for hwlat_detector tracer tracing: Added hardware latency tracer ftrace: Access ret_stack->subtime only in the function profiler function_graph: Handle TRACE_BPUTS in print_graph_comment tracing/uprobe: Drop isdigit() check in create_trace_uprobe
This commit is contained in:
Linus Torvalds
commit
95107b30be
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|
@ -858,11 +858,11 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
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When enabled, it will account time the task has been
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scheduled out as part of the function call.
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graph-time - When running function graph tracer, to include the
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time to call nested functions. When this is not set,
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the time reported for the function will only include
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the time the function itself executed for, not the time
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for functions that it called.
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graph-time - When running function profiler with function graph tracer,
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to include the time to call nested functions. When this is
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not set, the time reported for the function will only
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include the time the function itself executed for, not the
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time for functions that it called.
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record-cmd - When any event or tracer is enabled, a hook is enabled
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in the sched_switch trace point to fill comm cache
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|
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@ -0,0 +1,79 @@
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Introduction:
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-------------
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The tracer hwlat_detector is a special purpose tracer that is used to
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detect large system latencies induced by the behavior of certain underlying
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hardware or firmware, independent of Linux itself. The code was developed
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originally to detect SMIs (System Management Interrupts) on x86 systems,
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however there is nothing x86 specific about this patchset. It was
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originally written for use by the "RT" patch since the Real Time
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kernel is highly latency sensitive.
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SMIs are not serviced by the Linux kernel, which means that it does not
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even know that they are occuring. SMIs are instead set up by BIOS code
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and are serviced by BIOS code, usually for "critical" events such as
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management of thermal sensors and fans. Sometimes though, SMIs are used for
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other tasks and those tasks can spend an inordinate amount of time in the
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handler (sometimes measured in milliseconds). Obviously this is a problem if
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you are trying to keep event service latencies down in the microsecond range.
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The hardware latency detector works by hogging one of the cpus for configurable
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amounts of time (with interrupts disabled), polling the CPU Time Stamp Counter
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for some period, then looking for gaps in the TSC data. Any gap indicates a
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time when the polling was interrupted and since the interrupts are disabled,
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the only thing that could do that would be an SMI or other hardware hiccup
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(or an NMI, but those can be tracked).
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Note that the hwlat detector should *NEVER* be used in a production environment.
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It is intended to be run manually to determine if the hardware platform has a
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problem with long system firmware service routines.
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Usage:
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------
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Write the ASCII text "hwlat" into the current_tracer file of the tracing system
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(mounted at /sys/kernel/tracing or /sys/kernel/tracing). It is possible to
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redefine the threshold in microseconds (us) above which latency spikes will
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be taken into account.
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Example:
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# echo hwlat > /sys/kernel/tracing/current_tracer
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# echo 100 > /sys/kernel/tracing/tracing_thresh
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The /sys/kernel/tracing/hwlat_detector interface contains the following files:
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width - time period to sample with CPUs held (usecs)
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must be less than the total window size (enforced)
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window - total period of sampling, width being inside (usecs)
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By default the width is set to 500,000 and window to 1,000,000, meaning that
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for every 1,000,000 usecs (1s) the hwlat detector will spin for 500,000 usecs
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(0.5s). If tracing_thresh contains zero when hwlat tracer is enabled, it will
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change to a default of 10 usecs. If any latencies that exceed the threshold is
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observed then the data will be written to the tracing ring buffer.
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The minimum sleep time between periods is 1 millisecond. Even if width
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is less than 1 millisecond apart from window, to allow the system to not
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be totally starved.
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If tracing_thresh was zero when hwlat detector was started, it will be set
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back to zero if another tracer is loaded. Note, the last value in
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tracing_thresh that hwlat detector had will be saved and this value will
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be restored in tracing_thresh if it is still zero when hwlat detector is
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started again.
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The following tracing directory files are used by the hwlat_detector:
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in /sys/kernel/tracing:
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tracing_threshold - minimum latency value to be considered (usecs)
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tracing_max_latency - maximum hardware latency actually observed (usecs)
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tracing_cpumask - the CPUs to move the hwlat thread across
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hwlat_detector/width - specified amount of time to spin within window (usecs)
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hwlat_detector/window - amount of time between (width) runs (usecs)
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The hwlat detector's kernel thread will migrate across each CPU specified in
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tracing_cpumask between each window. To limit the migration, either modify
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tracing_cpumask, or modify the hwlat kernel thread (named [hwlatd]) CPU
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affinity directly, and the migration will stop.
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@ -139,7 +139,7 @@ static void ftrace_mod_code(void)
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clear_mod_flag();
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}
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void ftrace_nmi_enter(void)
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void arch_ftrace_nmi_enter(void)
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{
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if (atomic_inc_return(&nmi_running) & MOD_CODE_WRITE_FLAG) {
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smp_rmb();
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@ -150,7 +150,7 @@ void ftrace_nmi_enter(void)
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smp_mb();
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}
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void ftrace_nmi_exit(void)
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void arch_ftrace_nmi_exit(void)
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{
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/* Finish all executions before clearing nmi_running */
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smp_mb();
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|
|
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@ -794,7 +794,9 @@ struct ftrace_ret_stack {
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unsigned long ret;
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unsigned long func;
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unsigned long long calltime;
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#ifdef CONFIG_FUNCTION_PROFILER
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unsigned long long subtime;
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#endif
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#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
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unsigned long fp;
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#endif
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|
|
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@ -3,11 +3,34 @@
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#ifdef CONFIG_FTRACE_NMI_ENTER
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extern void ftrace_nmi_enter(void);
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extern void ftrace_nmi_exit(void);
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extern void arch_ftrace_nmi_enter(void);
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extern void arch_ftrace_nmi_exit(void);
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#else
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static inline void ftrace_nmi_enter(void) { }
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static inline void ftrace_nmi_exit(void) { }
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static inline void arch_ftrace_nmi_enter(void) { }
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static inline void arch_ftrace_nmi_exit(void) { }
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#endif
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#ifdef CONFIG_HWLAT_TRACER
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extern bool trace_hwlat_callback_enabled;
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extern void trace_hwlat_callback(bool enter);
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#endif
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static inline void ftrace_nmi_enter(void)
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{
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#ifdef CONFIG_HWLAT_TRACER
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if (trace_hwlat_callback_enabled)
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trace_hwlat_callback(true);
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#endif
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arch_ftrace_nmi_enter();
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}
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static inline void ftrace_nmi_exit(void)
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{
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arch_ftrace_nmi_exit();
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#ifdef CONFIG_HWLAT_TRACER
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if (trace_hwlat_callback_enabled)
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trace_hwlat_callback(false);
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#endif
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}
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#endif /* _LINUX_FTRACE_IRQ_H */
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|
|
|
|||
|
|
@ -216,6 +216,41 @@ config SCHED_TRACER
|
|||
This tracer tracks the latency of the highest priority task
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to be scheduled in, starting from the point it has woken up.
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config HWLAT_TRACER
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bool "Tracer to detect hardware latencies (like SMIs)"
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select GENERIC_TRACER
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help
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This tracer, when enabled will create one or more kernel threads,
|
||||
depening on what the cpumask file is set to, which each thread
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||||
spinning in a loop looking for interruptions caused by
|
||||
something other than the kernel. For example, if a
|
||||
System Management Interrupt (SMI) takes a noticeable amount of
|
||||
time, this tracer will detect it. This is useful for testing
|
||||
if a system is reliable for Real Time tasks.
|
||||
|
||||
Some files are created in the tracing directory when this
|
||||
is enabled:
|
||||
|
||||
hwlat_detector/width - time in usecs for how long to spin for
|
||||
hwlat_detector/window - time in usecs between the start of each
|
||||
iteration
|
||||
|
||||
A kernel thread is created that will spin with interrupts disabled
|
||||
for "width" microseconds in every "widow" cycle. It will not spin
|
||||
for "window - width" microseconds, where the system can
|
||||
continue to operate.
|
||||
|
||||
The output will appear in the trace and trace_pipe files.
|
||||
|
||||
When the tracer is not running, it has no affect on the system,
|
||||
but when it is running, it can cause the system to be
|
||||
periodically non responsive. Do not run this tracer on a
|
||||
production system.
|
||||
|
||||
To enable this tracer, echo in "hwlat" into the current_tracer
|
||||
file. Every time a latency is greater than tracing_thresh, it will
|
||||
be recorded into the ring buffer.
|
||||
|
||||
config ENABLE_DEFAULT_TRACERS
|
||||
bool "Trace process context switches and events"
|
||||
depends on !GENERIC_TRACER
|
||||
|
|
|
|||
|
|
@ -41,6 +41,7 @@ obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
|
|||
obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
|
||||
obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
|
||||
obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
|
||||
obj-$(CONFIG_HWLAT_TRACER) += trace_hwlat.o
|
||||
obj-$(CONFIG_NOP_TRACER) += trace_nop.o
|
||||
obj-$(CONFIG_STACK_TRACER) += trace_stack.o
|
||||
obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o
|
||||
|
|
|
|||
|
|
@ -872,7 +872,13 @@ function_profile_call(unsigned long ip, unsigned long parent_ip,
|
|||
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
|
||||
static int profile_graph_entry(struct ftrace_graph_ent *trace)
|
||||
{
|
||||
int index = trace->depth;
|
||||
|
||||
function_profile_call(trace->func, 0, NULL, NULL);
|
||||
|
||||
if (index >= 0 && index < FTRACE_RETFUNC_DEPTH)
|
||||
current->ret_stack[index].subtime = 0;
|
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|
||||
return 1;
|
||||
}
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|
||||
|
|
|
|||
|
|
@ -1047,7 +1047,7 @@ void disable_trace_on_warning(void)
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|||
*
|
||||
* Shows real state of the ring buffer if it is enabled or not.
|
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*/
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static int tracer_tracing_is_on(struct trace_array *tr)
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int tracer_tracing_is_on(struct trace_array *tr)
|
||||
{
|
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if (tr->trace_buffer.buffer)
|
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return ring_buffer_record_is_on(tr->trace_buffer.buffer);
|
||||
|
|
@ -4969,7 +4969,7 @@ tracing_thresh_write(struct file *filp, const char __user *ubuf,
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|||
return ret;
|
||||
}
|
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|
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#ifdef CONFIG_TRACER_MAX_TRACE
|
||||
#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
|
||||
|
||||
static ssize_t
|
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tracing_max_lat_read(struct file *filp, char __user *ubuf,
|
||||
|
|
@ -5892,7 +5892,7 @@ static const struct file_operations tracing_thresh_fops = {
|
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.llseek = generic_file_llseek,
|
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};
|
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|
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#ifdef CONFIG_TRACER_MAX_TRACE
|
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#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
|
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static const struct file_operations tracing_max_lat_fops = {
|
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.open = tracing_open_generic,
|
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.read = tracing_max_lat_read,
|
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|
|
@ -7222,7 +7222,7 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
|
|||
|
||||
create_trace_options_dir(tr);
|
||||
|
||||
#ifdef CONFIG_TRACER_MAX_TRACE
|
||||
#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
|
||||
trace_create_file("tracing_max_latency", 0644, d_tracer,
|
||||
&tr->max_latency, &tracing_max_lat_fops);
|
||||
#endif
|
||||
|
|
|
|||
|
|
@ -38,6 +38,7 @@ enum trace_type {
|
|||
TRACE_USER_STACK,
|
||||
TRACE_BLK,
|
||||
TRACE_BPUTS,
|
||||
TRACE_HWLAT,
|
||||
|
||||
__TRACE_LAST_TYPE,
|
||||
};
|
||||
|
|
@ -213,6 +214,8 @@ struct trace_array {
|
|||
*/
|
||||
struct trace_buffer max_buffer;
|
||||
bool allocated_snapshot;
|
||||
#endif
|
||||
#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
|
||||
unsigned long max_latency;
|
||||
#endif
|
||||
struct trace_pid_list __rcu *filtered_pids;
|
||||
|
|
@ -326,6 +329,7 @@ extern void __ftrace_bad_type(void);
|
|||
IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT); \
|
||||
IF_ASSIGN(var, ent, struct bprint_entry, TRACE_BPRINT); \
|
||||
IF_ASSIGN(var, ent, struct bputs_entry, TRACE_BPUTS); \
|
||||
IF_ASSIGN(var, ent, struct hwlat_entry, TRACE_HWLAT); \
|
||||
IF_ASSIGN(var, ent, struct trace_mmiotrace_rw, \
|
||||
TRACE_MMIO_RW); \
|
||||
IF_ASSIGN(var, ent, struct trace_mmiotrace_map, \
|
||||
|
|
@ -571,6 +575,7 @@ void tracing_reset_current(int cpu);
|
|||
void tracing_reset_all_online_cpus(void);
|
||||
int tracing_open_generic(struct inode *inode, struct file *filp);
|
||||
bool tracing_is_disabled(void);
|
||||
int tracer_tracing_is_on(struct trace_array *tr);
|
||||
struct dentry *trace_create_file(const char *name,
|
||||
umode_t mode,
|
||||
struct dentry *parent,
|
||||
|
|
|
|||
|
|
@ -322,3 +322,30 @@ FTRACE_ENTRY(branch, trace_branch,
|
|||
FILTER_OTHER
|
||||
);
|
||||
|
||||
|
||||
FTRACE_ENTRY(hwlat, hwlat_entry,
|
||||
|
||||
TRACE_HWLAT,
|
||||
|
||||
F_STRUCT(
|
||||
__field( u64, duration )
|
||||
__field( u64, outer_duration )
|
||||
__field( u64, nmi_total_ts )
|
||||
__field_struct( struct timespec, timestamp )
|
||||
__field_desc( long, timestamp, tv_sec )
|
||||
__field_desc( long, timestamp, tv_nsec )
|
||||
__field( unsigned int, nmi_count )
|
||||
__field( unsigned int, seqnum )
|
||||
),
|
||||
|
||||
F_printk("cnt:%u\tts:%010lu.%010lu\tinner:%llu\touter:%llunmi-ts:%llu\tnmi-count:%u\n",
|
||||
__entry->seqnum,
|
||||
__entry->tv_sec,
|
||||
__entry->tv_nsec,
|
||||
__entry->duration,
|
||||
__entry->outer_duration,
|
||||
__entry->nmi_total_ts,
|
||||
__entry->nmi_count),
|
||||
|
||||
FILTER_OTHER
|
||||
);
|
||||
|
|
|
|||
|
|
@ -1028,6 +1028,7 @@ static struct event_command trigger_traceon_cmd = {
|
|||
static struct event_command trigger_traceoff_cmd = {
|
||||
.name = "traceoff",
|
||||
.trigger_type = ETT_TRACE_ONOFF,
|
||||
.flags = EVENT_CMD_FL_POST_TRIGGER,
|
||||
.func = event_trigger_callback,
|
||||
.reg = register_trigger,
|
||||
.unreg = unregister_trigger,
|
||||
|
|
|
|||
|
|
@ -170,7 +170,6 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
|
|||
current->ret_stack[index].ret = ret;
|
||||
current->ret_stack[index].func = func;
|
||||
current->ret_stack[index].calltime = calltime;
|
||||
current->ret_stack[index].subtime = 0;
|
||||
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
|
||||
current->ret_stack[index].fp = frame_pointer;
|
||||
#endif
|
||||
|
|
@ -1183,6 +1182,11 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
|
|||
trace_seq_puts(s, "/* ");
|
||||
|
||||
switch (iter->ent->type) {
|
||||
case TRACE_BPUTS:
|
||||
ret = trace_print_bputs_msg_only(iter);
|
||||
if (ret != TRACE_TYPE_HANDLED)
|
||||
return ret;
|
||||
break;
|
||||
case TRACE_BPRINT:
|
||||
ret = trace_print_bprintk_msg_only(iter);
|
||||
if (ret != TRACE_TYPE_HANDLED)
|
||||
|
|
|
|||
|
|
@ -0,0 +1,633 @@
|
|||
/*
|
||||
* trace_hwlatdetect.c - A simple Hardware Latency detector.
|
||||
*
|
||||
* Use this tracer to detect large system latencies induced by the behavior of
|
||||
* certain underlying system hardware or firmware, independent of Linux itself.
|
||||
* The code was developed originally to detect the presence of SMIs on Intel
|
||||
* and AMD systems, although there is no dependency upon x86 herein.
|
||||
*
|
||||
* The classical example usage of this tracer is in detecting the presence of
|
||||
* SMIs or System Management Interrupts on Intel and AMD systems. An SMI is a
|
||||
* somewhat special form of hardware interrupt spawned from earlier CPU debug
|
||||
* modes in which the (BIOS/EFI/etc.) firmware arranges for the South Bridge
|
||||
* LPC (or other device) to generate a special interrupt under certain
|
||||
* circumstances, for example, upon expiration of a special SMI timer device,
|
||||
* due to certain external thermal readings, on certain I/O address accesses,
|
||||
* and other situations. An SMI hits a special CPU pin, triggers a special
|
||||
* SMI mode (complete with special memory map), and the OS is unaware.
|
||||
*
|
||||
* Although certain hardware-inducing latencies are necessary (for example,
|
||||
* a modern system often requires an SMI handler for correct thermal control
|
||||
* and remote management) they can wreak havoc upon any OS-level performance
|
||||
* guarantees toward low-latency, especially when the OS is not even made
|
||||
* aware of the presence of these interrupts. For this reason, we need a
|
||||
* somewhat brute force mechanism to detect these interrupts. In this case,
|
||||
* we do it by hogging all of the CPU(s) for configurable timer intervals,
|
||||
* sampling the built-in CPU timer, looking for discontiguous readings.
|
||||
*
|
||||
* WARNING: This implementation necessarily introduces latencies. Therefore,
|
||||
* you should NEVER use this tracer while running in a production
|
||||
* environment requiring any kind of low-latency performance
|
||||
* guarantee(s).
|
||||
*
|
||||
* Copyright (C) 2008-2009 Jon Masters, Red Hat, Inc. <jcm@redhat.com>
|
||||
* Copyright (C) 2013-2016 Steven Rostedt, Red Hat, Inc. <srostedt@redhat.com>
|
||||
*
|
||||
* Includes useful feedback from Clark Williams <clark@redhat.com>
|
||||
*
|
||||
* This file is licensed under the terms of the GNU General Public
|
||||
* License version 2. This program is licensed "as is" without any
|
||||
* warranty of any kind, whether express or implied.
|
||||
*/
|
||||
#include <linux/kthread.h>
|
||||
#include <linux/tracefs.h>
|
||||
#include <linux/uaccess.h>
|
||||
#include <linux/cpumask.h>
|
||||
#include <linux/delay.h>
|
||||
#include "trace.h"
|
||||
|
||||
static struct trace_array *hwlat_trace;
|
||||
|
||||
#define U64STR_SIZE 22 /* 20 digits max */
|
||||
|
||||
#define BANNER "hwlat_detector: "
|
||||
#define DEFAULT_SAMPLE_WINDOW 1000000 /* 1s */
|
||||
#define DEFAULT_SAMPLE_WIDTH 500000 /* 0.5s */
|
||||
#define DEFAULT_LAT_THRESHOLD 10 /* 10us */
|
||||
|
||||
/* sampling thread*/
|
||||
static struct task_struct *hwlat_kthread;
|
||||
|
||||
static struct dentry *hwlat_sample_width; /* sample width us */
|
||||
static struct dentry *hwlat_sample_window; /* sample window us */
|
||||
|
||||
/* Save the previous tracing_thresh value */
|
||||
static unsigned long save_tracing_thresh;
|
||||
|
||||
/* NMI timestamp counters */
|
||||
static u64 nmi_ts_start;
|
||||
static u64 nmi_total_ts;
|
||||
static int nmi_count;
|
||||
static int nmi_cpu;
|
||||
|
||||
/* Tells NMIs to call back to the hwlat tracer to record timestamps */
|
||||
bool trace_hwlat_callback_enabled;
|
||||
|
||||
/* If the user changed threshold, remember it */
|
||||
static u64 last_tracing_thresh = DEFAULT_LAT_THRESHOLD * NSEC_PER_USEC;
|
||||
|
||||
/* Individual latency samples are stored here when detected. */
|
||||
struct hwlat_sample {
|
||||
u64 seqnum; /* unique sequence */
|
||||
u64 duration; /* delta */
|
||||
u64 outer_duration; /* delta (outer loop) */
|
||||
u64 nmi_total_ts; /* Total time spent in NMIs */
|
||||
struct timespec timestamp; /* wall time */
|
||||
int nmi_count; /* # NMIs during this sample */
|
||||
};
|
||||
|
||||
/* keep the global state somewhere. */
|
||||
static struct hwlat_data {
|
||||
|
||||
struct mutex lock; /* protect changes */
|
||||
|
||||
u64 count; /* total since reset */
|
||||
|
||||
u64 sample_window; /* total sampling window (on+off) */
|
||||
u64 sample_width; /* active sampling portion of window */
|
||||
|
||||
} hwlat_data = {
|
||||
.sample_window = DEFAULT_SAMPLE_WINDOW,
|
||||
.sample_width = DEFAULT_SAMPLE_WIDTH,
|
||||
};
|
||||
|
||||
static void trace_hwlat_sample(struct hwlat_sample *sample)
|
||||
{
|
||||
struct trace_array *tr = hwlat_trace;
|
||||
struct trace_event_call *call = &event_hwlat;
|
||||
struct ring_buffer *buffer = tr->trace_buffer.buffer;
|
||||
struct ring_buffer_event *event;
|
||||
struct hwlat_entry *entry;
|
||||
unsigned long flags;
|
||||
int pc;
|
||||
|
||||
pc = preempt_count();
|
||||
local_save_flags(flags);
|
||||
|
||||
event = trace_buffer_lock_reserve(buffer, TRACE_HWLAT, sizeof(*entry),
|
||||
flags, pc);
|
||||
if (!event)
|
||||
return;
|
||||
entry = ring_buffer_event_data(event);
|
||||
entry->seqnum = sample->seqnum;
|
||||
entry->duration = sample->duration;
|
||||
entry->outer_duration = sample->outer_duration;
|
||||
entry->timestamp = sample->timestamp;
|
||||
entry->nmi_total_ts = sample->nmi_total_ts;
|
||||
entry->nmi_count = sample->nmi_count;
|
||||
|
||||
if (!call_filter_check_discard(call, entry, buffer, event))
|
||||
__buffer_unlock_commit(buffer, event);
|
||||
}
|
||||
|
||||
/* Macros to encapsulate the time capturing infrastructure */
|
||||
#define time_type u64
|
||||
#define time_get() trace_clock_local()
|
||||
#define time_to_us(x) div_u64(x, 1000)
|
||||
#define time_sub(a, b) ((a) - (b))
|
||||
#define init_time(a, b) (a = b)
|
||||
#define time_u64(a) a
|
||||
|
||||
void trace_hwlat_callback(bool enter)
|
||||
{
|
||||
if (smp_processor_id() != nmi_cpu)
|
||||
return;
|
||||
|
||||
/*
|
||||
* Currently trace_clock_local() calls sched_clock() and the
|
||||
* generic version is not NMI safe.
|
||||
*/
|
||||
if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK)) {
|
||||
if (enter)
|
||||
nmi_ts_start = time_get();
|
||||
else
|
||||
nmi_total_ts = time_get() - nmi_ts_start;
|
||||
}
|
||||
|
||||
if (enter)
|
||||
nmi_count++;
|
||||
}
|
||||
|
||||
/**
|
||||
* get_sample - sample the CPU TSC and look for likely hardware latencies
|
||||
*
|
||||
* Used to repeatedly capture the CPU TSC (or similar), looking for potential
|
||||
* hardware-induced latency. Called with interrupts disabled and with
|
||||
* hwlat_data.lock held.
|
||||
*/
|
||||
static int get_sample(void)
|
||||
{
|
||||
struct trace_array *tr = hwlat_trace;
|
||||
time_type start, t1, t2, last_t2;
|
||||
s64 diff, total, last_total = 0;
|
||||
u64 sample = 0;
|
||||
u64 thresh = tracing_thresh;
|
||||
u64 outer_sample = 0;
|
||||
int ret = -1;
|
||||
|
||||
do_div(thresh, NSEC_PER_USEC); /* modifies interval value */
|
||||
|
||||
nmi_cpu = smp_processor_id();
|
||||
nmi_total_ts = 0;
|
||||
nmi_count = 0;
|
||||
/* Make sure NMIs see this first */
|
||||
barrier();
|
||||
|
||||
trace_hwlat_callback_enabled = true;
|
||||
|
||||
init_time(last_t2, 0);
|
||||
start = time_get(); /* start timestamp */
|
||||
|
||||
do {
|
||||
|
||||
t1 = time_get(); /* we'll look for a discontinuity */
|
||||
t2 = time_get();
|
||||
|
||||
if (time_u64(last_t2)) {
|
||||
/* Check the delta from outer loop (t2 to next t1) */
|
||||
diff = time_to_us(time_sub(t1, last_t2));
|
||||
/* This shouldn't happen */
|
||||
if (diff < 0) {
|
||||
pr_err(BANNER "time running backwards\n");
|
||||
goto out;
|
||||
}
|
||||
if (diff > outer_sample)
|
||||
outer_sample = diff;
|
||||
}
|
||||
last_t2 = t2;
|
||||
|
||||
total = time_to_us(time_sub(t2, start)); /* sample width */
|
||||
|
||||
/* Check for possible overflows */
|
||||
if (total < last_total) {
|
||||
pr_err("Time total overflowed\n");
|
||||
break;
|
||||
}
|
||||
last_total = total;
|
||||
|
||||
/* This checks the inner loop (t1 to t2) */
|
||||
diff = time_to_us(time_sub(t2, t1)); /* current diff */
|
||||
|
||||
/* This shouldn't happen */
|
||||
if (diff < 0) {
|
||||
pr_err(BANNER "time running backwards\n");
|
||||
goto out;
|
||||
}
|
||||
|
||||
if (diff > sample)
|
||||
sample = diff; /* only want highest value */
|
||||
|
||||
} while (total <= hwlat_data.sample_width);
|
||||
|
||||
barrier(); /* finish the above in the view for NMIs */
|
||||
trace_hwlat_callback_enabled = false;
|
||||
barrier(); /* Make sure nmi_total_ts is no longer updated */
|
||||
|
||||
ret = 0;
|
||||
|
||||
/* If we exceed the threshold value, we have found a hardware latency */
|
||||
if (sample > thresh || outer_sample > thresh) {
|
||||
struct hwlat_sample s;
|
||||
|
||||
ret = 1;
|
||||
|
||||
/* We read in microseconds */
|
||||
if (nmi_total_ts)
|
||||
do_div(nmi_total_ts, NSEC_PER_USEC);
|
||||
|
||||
hwlat_data.count++;
|
||||
s.seqnum = hwlat_data.count;
|
||||
s.duration = sample;
|
||||
s.outer_duration = outer_sample;
|
||||
s.timestamp = CURRENT_TIME;
|
||||
s.nmi_total_ts = nmi_total_ts;
|
||||
s.nmi_count = nmi_count;
|
||||
trace_hwlat_sample(&s);
|
||||
|
||||
/* Keep a running maximum ever recorded hardware latency */
|
||||
if (sample > tr->max_latency)
|
||||
tr->max_latency = sample;
|
||||
}
|
||||
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
|
||||
static struct cpumask save_cpumask;
|
||||
static bool disable_migrate;
|
||||
|
||||
static void move_to_next_cpu(void)
|
||||
{
|
||||
static struct cpumask *current_mask;
|
||||
int next_cpu;
|
||||
|
||||
if (disable_migrate)
|
||||
return;
|
||||
|
||||
/* Just pick the first CPU on first iteration */
|
||||
if (!current_mask) {
|
||||
current_mask = &save_cpumask;
|
||||
get_online_cpus();
|
||||
cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);
|
||||
put_online_cpus();
|
||||
next_cpu = cpumask_first(current_mask);
|
||||
goto set_affinity;
|
||||
}
|
||||
|
||||
/*
|
||||
* If for some reason the user modifies the CPU affinity
|
||||
* of this thread, than stop migrating for the duration
|
||||
* of the current test.
|
||||
*/
|
||||
if (!cpumask_equal(current_mask, ¤t->cpus_allowed))
|
||||
goto disable;
|
||||
|
||||
get_online_cpus();
|
||||
cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);
|
||||
next_cpu = cpumask_next(smp_processor_id(), current_mask);
|
||||
put_online_cpus();
|
||||
|
||||
if (next_cpu >= nr_cpu_ids)
|
||||
next_cpu = cpumask_first(current_mask);
|
||||
|
||||
set_affinity:
|
||||
if (next_cpu >= nr_cpu_ids) /* Shouldn't happen! */
|
||||
goto disable;
|
||||
|
||||
cpumask_clear(current_mask);
|
||||
cpumask_set_cpu(next_cpu, current_mask);
|
||||
|
||||
sched_setaffinity(0, current_mask);
|
||||
return;
|
||||
|
||||
disable:
|
||||
disable_migrate = true;
|
||||
}
|
||||
|
||||
/*
|
||||
* kthread_fn - The CPU time sampling/hardware latency detection kernel thread
|
||||
*
|
||||
* Used to periodically sample the CPU TSC via a call to get_sample. We
|
||||
* disable interrupts, which does (intentionally) introduce latency since we
|
||||
* need to ensure nothing else might be running (and thus preempting).
|
||||
* Obviously this should never be used in production environments.
|
||||
*
|
||||
* Currently this runs on which ever CPU it was scheduled on, but most
|
||||
* real-world hardware latency situations occur across several CPUs,
|
||||
* but we might later generalize this if we find there are any actualy
|
||||
* systems with alternate SMI delivery or other hardware latencies.
|
||||
*/
|
||||
static int kthread_fn(void *data)
|
||||
{
|
||||
u64 interval;
|
||||
|
||||
while (!kthread_should_stop()) {
|
||||
|
||||
move_to_next_cpu();
|
||||
|
||||
local_irq_disable();
|
||||
get_sample();
|
||||
local_irq_enable();
|
||||
|
||||
mutex_lock(&hwlat_data.lock);
|
||||
interval = hwlat_data.sample_window - hwlat_data.sample_width;
|
||||
mutex_unlock(&hwlat_data.lock);
|
||||
|
||||
do_div(interval, USEC_PER_MSEC); /* modifies interval value */
|
||||
|
||||
/* Always sleep for at least 1ms */
|
||||
if (interval < 1)
|
||||
interval = 1;
|
||||
|
||||
if (msleep_interruptible(interval))
|
||||
break;
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* start_kthread - Kick off the hardware latency sampling/detector kthread
|
||||
*
|
||||
* This starts the kernel thread that will sit and sample the CPU timestamp
|
||||
* counter (TSC or similar) and look for potential hardware latencies.
|
||||
*/
|
||||
static int start_kthread(struct trace_array *tr)
|
||||
{
|
||||
struct task_struct *kthread;
|
||||
|
||||
kthread = kthread_create(kthread_fn, NULL, "hwlatd");
|
||||
if (IS_ERR(kthread)) {
|
||||
pr_err(BANNER "could not start sampling thread\n");
|
||||
return -ENOMEM;
|
||||
}
|
||||
hwlat_kthread = kthread;
|
||||
wake_up_process(kthread);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* stop_kthread - Inform the hardware latency samping/detector kthread to stop
|
||||
*
|
||||
* This kicks the running hardware latency sampling/detector kernel thread and
|
||||
* tells it to stop sampling now. Use this on unload and at system shutdown.
|
||||
*/
|
||||
static void stop_kthread(void)
|
||||
{
|
||||
if (!hwlat_kthread)
|
||||
return;
|
||||
kthread_stop(hwlat_kthread);
|
||||
hwlat_kthread = NULL;
|
||||
}
|
||||
|
||||
/*
|
||||
* hwlat_read - Wrapper read function for reading both window and width
|
||||
* @filp: The active open file structure
|
||||
* @ubuf: The userspace provided buffer to read value into
|
||||
* @cnt: The maximum number of bytes to read
|
||||
* @ppos: The current "file" position
|
||||
*
|
||||
* This function provides a generic read implementation for the global state
|
||||
* "hwlat_data" structure filesystem entries.
|
||||
*/
|
||||
static ssize_t hwlat_read(struct file *filp, char __user *ubuf,
|
||||
size_t cnt, loff_t *ppos)
|
||||
{
|
||||
char buf[U64STR_SIZE];
|
||||
u64 *entry = filp->private_data;
|
||||
u64 val;
|
||||
int len;
|
||||
|
||||
if (!entry)
|
||||
return -EFAULT;
|
||||
|
||||
if (cnt > sizeof(buf))
|
||||
cnt = sizeof(buf);
|
||||
|
||||
val = *entry;
|
||||
|
||||
len = snprintf(buf, sizeof(buf), "%llu\n", val);
|
||||
|
||||
return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
|
||||
}
|
||||
|
||||
/**
|
||||
* hwlat_width_write - Write function for "width" entry
|
||||
* @filp: The active open file structure
|
||||
* @ubuf: The user buffer that contains the value to write
|
||||
* @cnt: The maximum number of bytes to write to "file"
|
||||
* @ppos: The current position in @file
|
||||
*
|
||||
* This function provides a write implementation for the "width" interface
|
||||
* to the hardware latency detector. It can be used to configure
|
||||
* for how many us of the total window us we will actively sample for any
|
||||
* hardware-induced latency periods. Obviously, it is not possible to
|
||||
* sample constantly and have the system respond to a sample reader, or,
|
||||
* worse, without having the system appear to have gone out to lunch. It
|
||||
* is enforced that width is less that the total window size.
|
||||
*/
|
||||
static ssize_t
|
||||
hwlat_width_write(struct file *filp, const char __user *ubuf,
|
||||
size_t cnt, loff_t *ppos)
|
||||
{
|
||||
u64 val;
|
||||
int err;
|
||||
|
||||
err = kstrtoull_from_user(ubuf, cnt, 10, &val);
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
mutex_lock(&hwlat_data.lock);
|
||||
if (val < hwlat_data.sample_window)
|
||||
hwlat_data.sample_width = val;
|
||||
else
|
||||
err = -EINVAL;
|
||||
mutex_unlock(&hwlat_data.lock);
|
||||
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
return cnt;
|
||||
}
|
||||
|
||||
/**
|
||||
* hwlat_window_write - Write function for "window" entry
|
||||
* @filp: The active open file structure
|
||||
* @ubuf: The user buffer that contains the value to write
|
||||
* @cnt: The maximum number of bytes to write to "file"
|
||||
* @ppos: The current position in @file
|
||||
*
|
||||
* This function provides a write implementation for the "window" interface
|
||||
* to the hardware latency detetector. The window is the total time
|
||||
* in us that will be considered one sample period. Conceptually, windows
|
||||
* occur back-to-back and contain a sample width period during which
|
||||
* actual sampling occurs. Can be used to write a new total window size. It
|
||||
* is enfoced that any value written must be greater than the sample width
|
||||
* size, or an error results.
|
||||
*/
|
||||
static ssize_t
|
||||
hwlat_window_write(struct file *filp, const char __user *ubuf,
|
||||
size_t cnt, loff_t *ppos)
|
||||
{
|
||||
u64 val;
|
||||
int err;
|
||||
|
||||
err = kstrtoull_from_user(ubuf, cnt, 10, &val);
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
mutex_lock(&hwlat_data.lock);
|
||||
if (hwlat_data.sample_width < val)
|
||||
hwlat_data.sample_window = val;
|
||||
else
|
||||
err = -EINVAL;
|
||||
mutex_unlock(&hwlat_data.lock);
|
||||
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
return cnt;
|
||||
}
|
||||
|
||||
static const struct file_operations width_fops = {
|
||||
.open = tracing_open_generic,
|
||||
.read = hwlat_read,
|
||||
.write = hwlat_width_write,
|
||||
};
|
||||
|
||||
static const struct file_operations window_fops = {
|
||||
.open = tracing_open_generic,
|
||||
.read = hwlat_read,
|
||||
.write = hwlat_window_write,
|
||||
};
|
||||
|
||||
/**
|
||||
* init_tracefs - A function to initialize the tracefs interface files
|
||||
*
|
||||
* This function creates entries in tracefs for "hwlat_detector".
|
||||
* It creates the hwlat_detector directory in the tracing directory,
|
||||
* and within that directory is the count, width and window files to
|
||||
* change and view those values.
|
||||
*/
|
||||
static int init_tracefs(void)
|
||||
{
|
||||
struct dentry *d_tracer;
|
||||
struct dentry *top_dir;
|
||||
|
||||
d_tracer = tracing_init_dentry();
|
||||
if (IS_ERR(d_tracer))
|
||||
return -ENOMEM;
|
||||
|
||||
top_dir = tracefs_create_dir("hwlat_detector", d_tracer);
|
||||
if (!top_dir)
|
||||
return -ENOMEM;
|
||||
|
||||
hwlat_sample_window = tracefs_create_file("window", 0640,
|
||||
top_dir,
|
||||
&hwlat_data.sample_window,
|
||||
&window_fops);
|
||||
if (!hwlat_sample_window)
|
||||
goto err;
|
||||
|
||||
hwlat_sample_width = tracefs_create_file("width", 0644,
|
||||
top_dir,
|
||||
&hwlat_data.sample_width,
|
||||
&width_fops);
|
||||
if (!hwlat_sample_width)
|
||||
goto err;
|
||||
|
||||
return 0;
|
||||
|
||||
err:
|
||||
tracefs_remove_recursive(top_dir);
|
||||
return -ENOMEM;
|
||||
}
|
||||
|
||||
static void hwlat_tracer_start(struct trace_array *tr)
|
||||
{
|
||||
int err;
|
||||
|
||||
err = start_kthread(tr);
|
||||
if (err)
|
||||
pr_err(BANNER "Cannot start hwlat kthread\n");
|
||||
}
|
||||
|
||||
static void hwlat_tracer_stop(struct trace_array *tr)
|
||||
{
|
||||
stop_kthread();
|
||||
}
|
||||
|
||||
static bool hwlat_busy;
|
||||
|
||||
static int hwlat_tracer_init(struct trace_array *tr)
|
||||
{
|
||||
/* Only allow one instance to enable this */
|
||||
if (hwlat_busy)
|
||||
return -EBUSY;
|
||||
|
||||
hwlat_trace = tr;
|
||||
|
||||
disable_migrate = false;
|
||||
hwlat_data.count = 0;
|
||||
tr->max_latency = 0;
|
||||
save_tracing_thresh = tracing_thresh;
|
||||
|
||||
/* tracing_thresh is in nsecs, we speak in usecs */
|
||||
if (!tracing_thresh)
|
||||
tracing_thresh = last_tracing_thresh;
|
||||
|
||||
if (tracer_tracing_is_on(tr))
|
||||
hwlat_tracer_start(tr);
|
||||
|
||||
hwlat_busy = true;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void hwlat_tracer_reset(struct trace_array *tr)
|
||||
{
|
||||
stop_kthread();
|
||||
|
||||
/* the tracing threshold is static between runs */
|
||||
last_tracing_thresh = tracing_thresh;
|
||||
|
||||
tracing_thresh = save_tracing_thresh;
|
||||
hwlat_busy = false;
|
||||
}
|
||||
|
||||
static struct tracer hwlat_tracer __read_mostly =
|
||||
{
|
||||
.name = "hwlat",
|
||||
.init = hwlat_tracer_init,
|
||||
.reset = hwlat_tracer_reset,
|
||||
.start = hwlat_tracer_start,
|
||||
.stop = hwlat_tracer_stop,
|
||||
.allow_instances = true,
|
||||
};
|
||||
|
||||
__init static int init_hwlat_tracer(void)
|
||||
{
|
||||
int ret;
|
||||
|
||||
mutex_init(&hwlat_data.lock);
|
||||
|
||||
ret = register_tracer(&hwlat_tracer);
|
||||
if (ret)
|
||||
return ret;
|
||||
|
||||
init_tracefs();
|
||||
|
||||
return 0;
|
||||
}
|
||||
late_initcall(init_hwlat_tracer);
|
||||
|
|
@ -1098,6 +1098,71 @@ static struct trace_event trace_user_stack_event = {
|
|||
.funcs = &trace_user_stack_funcs,
|
||||
};
|
||||
|
||||
/* TRACE_HWLAT */
|
||||
static enum print_line_t
|
||||
trace_hwlat_print(struct trace_iterator *iter, int flags,
|
||||
struct trace_event *event)
|
||||
{
|
||||
struct trace_entry *entry = iter->ent;
|
||||
struct trace_seq *s = &iter->seq;
|
||||
struct hwlat_entry *field;
|
||||
|
||||
trace_assign_type(field, entry);
|
||||
|
||||
trace_seq_printf(s, "#%-5u inner/outer(us): %4llu/%-5llu ts:%ld.%09ld",
|
||||
field->seqnum,
|
||||
field->duration,
|
||||
field->outer_duration,
|
||||
field->timestamp.tv_sec,
|
||||
field->timestamp.tv_nsec);
|
||||
|
||||
if (field->nmi_count) {
|
||||
/*
|
||||
* The generic sched_clock() is not NMI safe, thus
|
||||
* we only record the count and not the time.
|
||||
*/
|
||||
if (!IS_ENABLED(CONFIG_GENERIC_SCHED_CLOCK))
|
||||
trace_seq_printf(s, " nmi-total:%llu",
|
||||
field->nmi_total_ts);
|
||||
trace_seq_printf(s, " nmi-count:%u",
|
||||
field->nmi_count);
|
||||
}
|
||||
|
||||
trace_seq_putc(s, '\n');
|
||||
|
||||
return trace_handle_return(s);
|
||||
}
|
||||
|
||||
|
||||
static enum print_line_t
|
||||
trace_hwlat_raw(struct trace_iterator *iter, int flags,
|
||||
struct trace_event *event)
|
||||
{
|
||||
struct hwlat_entry *field;
|
||||
struct trace_seq *s = &iter->seq;
|
||||
|
||||
trace_assign_type(field, iter->ent);
|
||||
|
||||
trace_seq_printf(s, "%llu %lld %ld %09ld %u\n",
|
||||
field->duration,
|
||||
field->outer_duration,
|
||||
field->timestamp.tv_sec,
|
||||
field->timestamp.tv_nsec,
|
||||
field->seqnum);
|
||||
|
||||
return trace_handle_return(s);
|
||||
}
|
||||
|
||||
static struct trace_event_functions trace_hwlat_funcs = {
|
||||
.trace = trace_hwlat_print,
|
||||
.raw = trace_hwlat_raw,
|
||||
};
|
||||
|
||||
static struct trace_event trace_hwlat_event = {
|
||||
.type = TRACE_HWLAT,
|
||||
.funcs = &trace_hwlat_funcs,
|
||||
};
|
||||
|
||||
/* TRACE_BPUTS */
|
||||
static enum print_line_t
|
||||
trace_bputs_print(struct trace_iterator *iter, int flags,
|
||||
|
|
@ -1233,6 +1298,7 @@ static struct trace_event *events[] __initdata = {
|
|||
&trace_bputs_event,
|
||||
&trace_bprint_event,
|
||||
&trace_print_event,
|
||||
&trace_hwlat_event,
|
||||
NULL
|
||||
};
|
||||
|
||||
|
|
|
|||
|
|
@ -431,10 +431,6 @@ static int create_trace_uprobe(int argc, char **argv)
|
|||
pr_info("Probe point is not specified.\n");
|
||||
return -EINVAL;
|
||||
}
|
||||
if (isdigit(argv[1][0])) {
|
||||
pr_info("probe point must be have a filename.\n");
|
||||
return -EINVAL;
|
||||
}
|
||||
arg = strchr(argv[1], ':');
|
||||
if (!arg) {
|
||||
ret = -EINVAL;
|
||||
|
|
|
|||
|
|
@ -0,0 +1,115 @@
|
|||
#!/bin/bash
|
||||
#
|
||||
# Here's how to use this:
|
||||
#
|
||||
# This script is used to help find functions that are being traced by function
|
||||
# tracer or function graph tracing that causes the machine to reboot, hang, or
|
||||
# crash. Here's the steps to take.
|
||||
#
|
||||
# First, determine if function tracing is working with a single function:
|
||||
#
|
||||
# (note, if this is a problem with function_graph tracing, then simply
|
||||
# replace "function" with "function_graph" in the following steps).
|
||||
#
|
||||
# # cd /sys/kernel/debug/tracing
|
||||
# # echo schedule > set_ftrace_filter
|
||||
# # echo function > current_tracer
|
||||
#
|
||||
# If this works, then we know that something is being traced that shouldn't be.
|
||||
#
|
||||
# # echo nop > current_tracer
|
||||
#
|
||||
# # cat available_filter_functions > ~/full-file
|
||||
# # ftrace-bisect ~/full-file ~/test-file ~/non-test-file
|
||||
# # cat ~/test-file > set_ftrace_filter
|
||||
#
|
||||
# *** Note *** this will take several minutes. Setting multiple functions is
|
||||
# an O(n^2) operation, and we are dealing with thousands of functions. So go
|
||||
# have coffee, talk with your coworkers, read facebook. And eventually, this
|
||||
# operation will end.
|
||||
#
|
||||
# # echo function > current_tracer
|
||||
#
|
||||
# If it crashes, we know that ~/test-file has a bad function.
|
||||
#
|
||||
# Reboot back to test kernel.
|
||||
#
|
||||
# # cd /sys/kernel/debug/tracing
|
||||
# # mv ~/test-file ~/full-file
|
||||
#
|
||||
# If it didn't crash.
|
||||
#
|
||||
# # echo nop > current_tracer
|
||||
# # mv ~/non-test-file ~/full-file
|
||||
#
|
||||
# Get rid of the other test file from previous run (or save them off somewhere).
|
||||
# # rm -f ~/test-file ~/non-test-file
|
||||
#
|
||||
# And start again:
|
||||
#
|
||||
# # ftrace-bisect ~/full-file ~/test-file ~/non-test-file
|
||||
#
|
||||
# The good thing is, because this cuts the number of functions in ~/test-file
|
||||
# by half, the cat of it into set_ftrace_filter takes half as long each
|
||||
# iteration, so don't talk so much at the water cooler the second time.
|
||||
#
|
||||
# Eventually, if you did this correctly, you will get down to the problem
|
||||
# function, and all we need to do is to notrace it.
|
||||
#
|
||||
# The way to figure out if the problem function is bad, just do:
|
||||
#
|
||||
# # echo <problem-function> > set_ftrace_notrace
|
||||
# # echo > set_ftrace_filter
|
||||
# # echo function > current_tracer
|
||||
#
|
||||
# And if it doesn't crash, we are done.
|
||||
#
|
||||
# If it does crash, do this again (there's more than one problem function)
|
||||
# but you need to echo the problem function(s) into set_ftrace_notrace before
|
||||
# enabling function tracing in the above steps. Or if you can compile the
|
||||
# kernel, annotate the problem functions with "notrace" and start again.
|
||||
#
|
||||
|
||||
|
||||
if [ $# -ne 3 ]; then
|
||||
echo 'usage: ftrace-bisect full-file test-file non-test-file'
|
||||
exit
|
||||
fi
|
||||
|
||||
full=$1
|
||||
test=$2
|
||||
nontest=$3
|
||||
|
||||
x=`cat $full | wc -l`
|
||||
if [ $x -eq 1 ]; then
|
||||
echo "There's only one function left, must be the bad one"
|
||||
cat $full
|
||||
exit 0
|
||||
fi
|
||||
|
||||
let x=$x/2
|
||||
let y=$x+1
|
||||
|
||||
if [ ! -f $full ]; then
|
||||
echo "$full does not exist"
|
||||
exit 1
|
||||
fi
|
||||
|
||||
if [ -f $test ]; then
|
||||
echo -n "$test exists, delete it? [y/N]"
|
||||
read a
|
||||
if [ "$a" != "y" -a "$a" != "Y" ]; then
|
||||
exit 1
|
||||
fi
|
||||
fi
|
||||
|
||||
if [ -f $nontest ]; then
|
||||
echo -n "$nontest exists, delete it? [y/N]"
|
||||
read a
|
||||
if [ "$a" != "y" -a "$a" != "Y" ]; then
|
||||
exit 1
|
||||
fi
|
||||
fi
|
||||
|
||||
sed -ne "1,${x}p" $full > $test
|
||||
sed -ne "$y,\$p" $full > $nontest
|
||||
Loading…
Reference in New Issue