openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity
linux/arch/x86/kernel/trace.c

235 lines
7.4 KiB
C
Raw Normal View History

trace: Add osnoise tracer In the context of high-performance computing (HPC), the Operating System Noise (*osnoise*) refers to the interference experienced by an application due to activities inside the operating system. In the context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread can cause noise to the system. Moreover, hardware-related jobs can also cause noise, for example, via SMIs. The osnoise tracer leverages the hwlat_detector by running a similar loop with preemption, SoftIRQs and IRQs enabled, thus allowing all the sources of *osnoise* during its execution. Using the same approach of hwlat, osnoise takes note of the entry and exit point of any source of interferences, increasing a per-cpu interference counter. The osnoise tracer also saves an interference counter for each source of interference. The interference counter for NMI, IRQs, SoftIRQs, and threads is increased anytime the tool observes these interferences' entry events. When a noise happens without any interference from the operating system level, the hardware noise counter increases, pointing to a hardware-related noise. In this way, osnoise can account for any source of interference. At the end of the period, the osnoise tracer prints the sum of all noise, the max single noise, the percentage of CPU available for the thread, and the counters for the noise sources. Usage Write the ASCII text "osnoise" into the current_tracer file of the tracing system (generally mounted at /sys/kernel/tracing). For example:: [root@f32 ~]# cd /sys/kernel/tracing/ [root@f32 tracing]# echo osnoise > current_tracer It is possible to follow the trace by reading the trace trace file:: [root@f32 tracing]# cat trace # tracer: osnoise # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth MAX # || / SINGLE Interference counters: # |||| RUNTIME NOISE % OF CPU NOISE +-----------------------------+ # TASK-PID CPU# |||| TIMESTAMP IN US IN US AVAILABLE IN US HW NMI IRQ SIRQ THREAD # | | | |||| | | | | | | | | | | <...>-859 [000] .... 81.637220: 1000000 190 99.98100 9 18 0 1007 18 1 <...>-860 [001] .... 81.638154: 1000000 656 99.93440 74 23 0 1006 16 3 <...>-861 [002] .... 81.638193: 1000000 5675 99.43250 202 6 0 1013 25 21 <...>-862 [003] .... 81.638242: 1000000 125 99.98750 45 1 0 1011 23 0 <...>-863 [004] .... 81.638260: 1000000 1721 99.82790 168 7 0 1002 49 41 <...>-864 [005] .... 81.638286: 1000000 263 99.97370 57 6 0 1006 26 2 <...>-865 [006] .... 81.638302: 1000000 109 99.98910 21 3 0 1006 18 1 <...>-866 [007] .... 81.638326: 1000000 7816 99.21840 107 8 0 1016 39 19 In addition to the regular trace fields (from TASK-PID to TIMESTAMP), the tracer prints a message at the end of each period for each CPU that is running an osnoise/CPU thread. The osnoise specific fields report: - The RUNTIME IN USE reports the amount of time in microseconds that the osnoise thread kept looping reading the time. - The NOISE IN US reports the sum of noise in microseconds observed by the osnoise tracer during the associated runtime. - The % OF CPU AVAILABLE reports the percentage of CPU available for the osnoise thread during the runtime window. - The MAX SINGLE NOISE IN US reports the maximum single noise observed during the runtime window. - The Interference counters display how many each of the respective interference happened during the runtime window. Note that the example above shows a high number of HW noise samples. The reason being is that this sample was taken on a virtual machine, and the host interference is detected as a hardware interference. Tracer options The tracer has a set of options inside the osnoise directory, they are: - osnoise/cpus: CPUs at which a osnoise thread will execute. - osnoise/period_us: the period of the osnoise thread. - osnoise/runtime_us: how long an osnoise thread will look for noise. - osnoise/stop_tracing_us: stop the system tracing if a single noise higher than the configured value happens. Writing 0 disables this option. - osnoise/stop_tracing_total_us: stop the system tracing if total noise higher than the configured value happens. Writing 0 disables this option. - tracing_threshold: the minimum delta between two time() reads to be considered as noise, in us. When set to 0, the default value will be used, which is currently 5 us. Additional Tracing In addition to the tracer, a set of tracepoints were added to facilitate the identification of the osnoise source. - osnoise:sample_threshold: printed anytime a noise is higher than the configurable tolerance_ns. - osnoise:nmi_noise: noise from NMI, including the duration. - osnoise:irq_noise: noise from an IRQ, including the duration. - osnoise:softirq_noise: noise from a SoftIRQ, including the duration. - osnoise:thread_noise: noise from a thread, including the duration. Note that all the values are *net values*. For example, if while osnoise is running, another thread preempts the osnoise thread, it will start a thread_noise duration at the start. Then, an IRQ takes place, preempting the thread_noise, starting a irq_noise. When the IRQ ends its execution, it will compute its duration, and this duration will be subtracted from the thread_noise, in such a way as to avoid the double accounting of the IRQ execution. This logic is valid for all sources of noise. Here is one example of the usage of these tracepoints:: osnoise/8-961 [008] d.h. 5789.857532: irq_noise: local_timer:236 start 5789.857529929 duration 1845 ns osnoise/8-961 [008] dNh. 5789.858408: irq_noise: local_timer:236 start 5789.858404871 duration 2848 ns migration/8-54 [008] d... 5789.858413: thread_noise: migration/8:54 start 5789.858409300 duration 3068 ns osnoise/8-961 [008] .... 5789.858413: sample_threshold: start 5789.858404555 duration 8723 ns interferences 2 In this example, a noise sample of 8 microseconds was reported in the last line, pointing to two interferences. Looking backward in the trace, the two previous entries were about the migration thread running after a timer IRQ execution. The first event is not part of the noise because it took place one millisecond before. It is worth noticing that the sum of the duration reported in the tracepoints is smaller than eight us reported in the sample_threshold. The reason roots in the overhead of the entry and exit code that happens before and after any interference execution. This justifies the dual approach: measuring thread and tracing. Link: https://lkml.kernel.org/r/e649467042d60e7b62714c9c6751a56299d15119.1624372313.git.bristot@redhat.com Cc: Phil Auld <pauld@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Kate Carcia <kcarcia@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Alexandre Chartre <alexandre.chartre@oracle.com> Cc: Clark Willaims <williams@redhat.com> Cc: John Kacur <jkacur@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> [ Made the following functions static: trace_irqentry_callback() trace_irqexit_callback() trace_intel_irqentry_callback() trace_intel_irqexit_callback() Added to include/trace.h: osnoise_arch_register() osnoise_arch_unregister() Fixed define logic for LATENCY_FS_NOTIFY Reported-by: kernel test robot <lkp@intel.com> ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-06-22 22:42:27 +08:00
#include <asm/trace/irq_vectors.h>
#include <linux/trace.h>
#if defined(CONFIG_OSNOISE_TRACER) && defined(CONFIG_X86_LOCAL_APIC)
/*
* trace_intel_irq_entry - record intel specific IRQ entry
*/
static void trace_intel_irq_entry(void *data, int vector)
{
osnoise_trace_irq_entry(vector);
}
/*
* trace_intel_irq_exit - record intel specific IRQ exit
*/
static void trace_intel_irq_exit(void *data, int vector)
{
char *vector_desc = (char *) data;
osnoise_trace_irq_exit(vector, vector_desc);
}
/*
* register_intel_irq_tp - Register intel specific IRQ entry tracepoints
*/
int osnoise_arch_register(void)
{
int ret;
ret = register_trace_local_timer_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_err;
ret = register_trace_local_timer_exit(trace_intel_irq_exit, "local_timer");
if (ret)
goto out_timer_entry;
#ifdef CONFIG_X86_THERMAL_VECTOR
ret = register_trace_thermal_apic_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_timer_exit;
ret = register_trace_thermal_apic_exit(trace_intel_irq_exit, "thermal_apic");
if (ret)
goto out_thermal_entry;
#endif /* CONFIG_X86_THERMAL_VECTOR */
#ifdef CONFIG_X86_MCE_AMD
ret = register_trace_deferred_error_apic_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_thermal_exit;
ret = register_trace_deferred_error_apic_exit(trace_intel_irq_exit, "deferred_error");
if (ret)
goto out_deferred_entry;
#endif
#ifdef CONFIG_X86_MCE_THRESHOLD
ret = register_trace_threshold_apic_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_deferred_exit;
ret = register_trace_threshold_apic_exit(trace_intel_irq_exit, "threshold_apic");
if (ret)
goto out_threshold_entry;
#endif /* CONFIG_X86_MCE_THRESHOLD */
#ifdef CONFIG_SMP
ret = register_trace_call_function_single_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_threshold_exit;
ret = register_trace_call_function_single_exit(trace_intel_irq_exit,
"call_function_single");
if (ret)
goto out_call_function_single_entry;
ret = register_trace_call_function_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_call_function_single_exit;
ret = register_trace_call_function_exit(trace_intel_irq_exit, "call_function");
if (ret)
goto out_call_function_entry;
ret = register_trace_reschedule_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_call_function_exit;
ret = register_trace_reschedule_exit(trace_intel_irq_exit, "reschedule");
if (ret)
goto out_reschedule_entry;
#endif /* CONFIG_SMP */
#ifdef CONFIG_IRQ_WORK
ret = register_trace_irq_work_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_reschedule_exit;
ret = register_trace_irq_work_exit(trace_intel_irq_exit, "irq_work");
if (ret)
goto out_irq_work_entry;
#endif
ret = register_trace_x86_platform_ipi_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_irq_work_exit;
ret = register_trace_x86_platform_ipi_exit(trace_intel_irq_exit, "x86_platform_ipi");
if (ret)
goto out_x86_ipi_entry;
ret = register_trace_error_apic_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_x86_ipi_exit;
ret = register_trace_error_apic_exit(trace_intel_irq_exit, "error_apic");
if (ret)
goto out_error_apic_entry;
ret = register_trace_spurious_apic_entry(trace_intel_irq_entry, NULL);
if (ret)
goto out_error_apic_exit;
ret = register_trace_spurious_apic_exit(trace_intel_irq_exit, "spurious_apic");
if (ret)
goto out_spurious_apic_entry;
return 0;
out_spurious_apic_entry:
unregister_trace_spurious_apic_entry(trace_intel_irq_entry, NULL);
out_error_apic_exit:
unregister_trace_error_apic_exit(trace_intel_irq_exit, "error_apic");
out_error_apic_entry:
unregister_trace_error_apic_entry(trace_intel_irq_entry, NULL);
out_x86_ipi_exit:
unregister_trace_x86_platform_ipi_exit(trace_intel_irq_exit, "x86_platform_ipi");
out_x86_ipi_entry:
unregister_trace_x86_platform_ipi_entry(trace_intel_irq_entry, NULL);
out_irq_work_exit:
#ifdef CONFIG_IRQ_WORK
unregister_trace_irq_work_exit(trace_intel_irq_exit, "irq_work");
out_irq_work_entry:
unregister_trace_irq_work_entry(trace_intel_irq_entry, NULL);
out_reschedule_exit:
#endif
#ifdef CONFIG_SMP
unregister_trace_reschedule_exit(trace_intel_irq_exit, "reschedule");
out_reschedule_entry:
unregister_trace_reschedule_entry(trace_intel_irq_entry, NULL);
out_call_function_exit:
unregister_trace_call_function_exit(trace_intel_irq_exit, "call_function");
out_call_function_entry:
unregister_trace_call_function_entry(trace_intel_irq_entry, NULL);
out_call_function_single_exit:
unregister_trace_call_function_single_exit(trace_intel_irq_exit, "call_function_single");
out_call_function_single_entry:
unregister_trace_call_function_single_entry(trace_intel_irq_entry, NULL);
out_threshold_exit:
#endif
#ifdef CONFIG_X86_MCE_THRESHOLD
unregister_trace_threshold_apic_exit(trace_intel_irq_exit, "threshold_apic");
out_threshold_entry:
unregister_trace_threshold_apic_entry(trace_intel_irq_entry, NULL);
out_deferred_exit:
#endif
#ifdef CONFIG_X86_MCE_AMD
unregister_trace_deferred_error_apic_exit(trace_intel_irq_exit, "deferred_error");
out_deferred_entry:
unregister_trace_deferred_error_apic_entry(trace_intel_irq_entry, NULL);
out_thermal_exit:
#endif /* CONFIG_X86_MCE_AMD */
#ifdef CONFIG_X86_THERMAL_VECTOR
unregister_trace_thermal_apic_exit(trace_intel_irq_exit, "thermal_apic");
out_thermal_entry:
unregister_trace_thermal_apic_entry(trace_intel_irq_entry, NULL);
out_timer_exit:
#endif /* CONFIG_X86_THERMAL_VECTOR */
unregister_trace_local_timer_exit(trace_intel_irq_exit, "local_timer");
out_timer_entry:
unregister_trace_local_timer_entry(trace_intel_irq_entry, NULL);
out_err:
return -EINVAL;
}
void osnoise_arch_unregister(void)
{
unregister_trace_spurious_apic_exit(trace_intel_irq_exit, "spurious_apic");
unregister_trace_spurious_apic_entry(trace_intel_irq_entry, NULL);
unregister_trace_error_apic_exit(trace_intel_irq_exit, "error_apic");
unregister_trace_error_apic_entry(trace_intel_irq_entry, NULL);
unregister_trace_x86_platform_ipi_exit(trace_intel_irq_exit, "x86_platform_ipi");
unregister_trace_x86_platform_ipi_entry(trace_intel_irq_entry, NULL);
#ifdef CONFIG_IRQ_WORK
unregister_trace_irq_work_exit(trace_intel_irq_exit, "irq_work");
unregister_trace_irq_work_entry(trace_intel_irq_entry, NULL);
#endif
#ifdef CONFIG_SMP
unregister_trace_reschedule_exit(trace_intel_irq_exit, "reschedule");
unregister_trace_reschedule_entry(trace_intel_irq_entry, NULL);
unregister_trace_call_function_exit(trace_intel_irq_exit, "call_function");
unregister_trace_call_function_entry(trace_intel_irq_entry, NULL);
unregister_trace_call_function_single_exit(trace_intel_irq_exit, "call_function_single");
unregister_trace_call_function_single_entry(trace_intel_irq_entry, NULL);
#endif
#ifdef CONFIG_X86_MCE_THRESHOLD
unregister_trace_threshold_apic_exit(trace_intel_irq_exit, "threshold_apic");
unregister_trace_threshold_apic_entry(trace_intel_irq_entry, NULL);
#endif
#ifdef CONFIG_X86_MCE_AMD
unregister_trace_deferred_error_apic_exit(trace_intel_irq_exit, "deferred_error");
unregister_trace_deferred_error_apic_entry(trace_intel_irq_entry, NULL);
#endif
#ifdef CONFIG_X86_THERMAL_VECTOR
unregister_trace_thermal_apic_exit(trace_intel_irq_exit, "thermal_apic");
unregister_trace_thermal_apic_entry(trace_intel_irq_entry, NULL);
#endif /* CONFIG_X86_THERMAL_VECTOR */
unregister_trace_local_timer_exit(trace_intel_irq_exit, "local_timer");
unregister_trace_local_timer_entry(trace_intel_irq_entry, NULL);
}
#endif /* CONFIG_OSNOISE_TRAECR && CONFIG_X86_LOCAL_APIC */