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SubjectRe: [PATCH V8 06/14] rtla: Add timerlat tool and timelart top mode
On Mon, Nov 29, 2021 at 12:07:44PM +0100,
Daniel Bristot de Oliveira wrote:

> The rtla timerlat tool is an interface for the timerlat tracer.
> The timerlat tracer dispatches a kernel thread per-cpu. These threads set a
> periodic timer to wake themselves up and go back to sleep. After the
> wakeup, they collect and generate useful information for the debugging of
> operating system timer latency.
>
> The timerlat tracer outputs information in two ways. It periodically
> prints the timer latency at the timer IRQ handler and the Thread handler.
> It also provides information for each noise via the osnoise tracepoints.
>
> The rtla timerlat top mode displays a summary of the periodic output from
> the timerlat tracer.
>
> Here is one example of the rtla timerlat tool output:
> ---------- %< ----------
> [root@alien ~]# rtla timerlat top -c 0-3 -d 1m
> Timer Latency
> 0 00:01:00 | IRQ Timer Latency (us) | Thread Timer Latency (us)
> CPU COUNT | cur min avg max | cur min avg max
> 0 #60001 | 0 0 0 3 | 1 1 1 6
> 1 #60001 | 0 0 0 3 | 2 1 1 5
> 2 #60001 | 0 0 1 6 | 1 1 2 7
> 3 #60001 | 0 0 0 7 | 1 1 1 11
> ---------- >% ----------
>
> Running:
> # rtla timerlat --help
> # rtla timerlat top --help
> provides information about the available options.
>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Tom Zanussi <zanussi@kernel.org>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: Juri Lelli <juri.lelli@redhat.com>
> Cc: Clark Williams <williams@redhat.com>
> Cc: John Kacur <jkacur@redhat.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
> Cc: linux-rt-users@vger.kernel.org
> Cc: linux-trace-devel@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
> ---
> tools/tracing/rtla/Makefile | 2 +
> tools/tracing/rtla/src/rtla.c | 5 +
> tools/tracing/rtla/src/timerlat.c | 68 +++
> tools/tracing/rtla/src/timerlat.h | 4 +
> tools/tracing/rtla/src/timerlat_top.c | 615 ++++++++++++++++++++++++++
> 5 files changed, 694 insertions(+)
> create mode 100644 tools/tracing/rtla/src/timerlat.c
> create mode 100644 tools/tracing/rtla/src/timerlat.h
> create mode 100644 tools/tracing/rtla/src/timerlat_top.c
>
> diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
> index ba6f327e815a..f254cfbe4fa3 100644
> --- a/tools/tracing/rtla/Makefile
> +++ b/tools/tracing/rtla/Makefile
> @@ -62,6 +62,8 @@ install:
> $(STRIP) $(DESTDIR)$(BINDIR)/rtla
> @test ! -f $(DESTDIR)$(BINDIR)/osnoise || rm $(DESTDIR)$(BINDIR)/osnoise
> ln -s $(DESTDIR)$(BINDIR)/rtla $(DESTDIR)$(BINDIR)/osnoise
> + @test ! -f $(DESTDIR)$(BINDIR)/timerlat || rm $(DESTDIR)$(BINDIR)/timerlat
> + ln -s $(DESTDIR)$(BINDIR)/rtla $(DESTDIR)$(BINDIR)/timerlat
>
> .PHONY: clean tarball
> clean:
> diff --git a/tools/tracing/rtla/src/rtla.c b/tools/tracing/rtla/src/rtla.c
> index 669b9750b3b3..09bd21b8af81 100644
> --- a/tools/tracing/rtla/src/rtla.c
> +++ b/tools/tracing/rtla/src/rtla.c
> @@ -9,6 +9,7 @@
> #include <stdio.h>
>
> #include "osnoise.h"
> +#include "timerlat.h"
>
> /*
> * rtla_usage - print rtla usage
> @@ -25,6 +26,7 @@ static void rtla_usage(void)
> "",
> " commands:",
> " osnoise - gives information about the operating system noise (osnoise)",
> + " timerlat - measures the timer irq and thread latency",
> "",
> NULL,
> };
> @@ -45,6 +47,9 @@ int run_command(int argc, char **argv, int start_position)
> if (strcmp(argv[start_position], "osnoise") == 0) {
> osnoise_main(argc-start_position, &argv[start_position]);
> goto ran;
> + } else if (strcmp(argv[start_position], "timerlat") == 0) {
> + timerlat_main(argc-start_position, &argv[start_position]);
> + goto ran;
> }
>
> return 0;
> diff --git a/tools/tracing/rtla/src/timerlat.c b/tools/tracing/rtla/src/timerlat.c
> new file mode 100644
> index 000000000000..29a51c01b084
> --- /dev/null
> +++ b/tools/tracing/rtla/src/timerlat.c
> @@ -0,0 +1,68 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
> + */
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <pthread.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +
> +#include "timerlat.h"
> +
> +static void timerlat_usage(void)
> +{
> + int i;
> +
> + static const char * const msg[] = {
> + "",
> + "timerlat version " VERSION,
> + "",
> + " usage: [rtla] timerlat [MODE] ...",
> + "",
> + " modes:",
> + " top - prints the summary from timerlat tracer",
> + "",
> + "if no MODE is given, the top mode is called, passing the arguments",
> + NULL,
> + };
> +
> + for (i = 0; msg[i]; i++)
> + fprintf(stderr, "%s\n", msg[i]);
> + exit(1);
> +}
> +
> +int timerlat_main(int argc, char *argv[])
> +{
> + if (argc == 0)
> + goto usage;
> +
> + /*
> + * if timerlat was called without any argument, run the
> + * default cmdline.
> + */
> + if (argc == 1) {
> + timerlat_top_main(argc, argv);
> + exit(0);
> + }
> +
> + if ((strcmp(argv[1], "-h") == 0) || (strcmp(argv[1], "--help") == 0)) {
> + timerlat_usage();
> + exit(0);
> + } else if (strncmp(argv[1], "-", 1) == 0) {
> + /* the user skipped the tool, call the default one */
> + timerlat_top_main(argc, argv);
> + exit(0);
> + } else if (strcmp(argv[1], "top") == 0) {
> + timerlat_top_main(argc-1, &argv[1]);
> + exit(0);
> + }
> +
> +usage:
> + timerlat_usage();
> + exit(1);
> +}
> diff --git a/tools/tracing/rtla/src/timerlat.h b/tools/tracing/rtla/src/timerlat.h
> new file mode 100644
> index 000000000000..6f9d3925acd0
> --- /dev/null
> +++ b/tools/tracing/rtla/src/timerlat.h
> @@ -0,0 +1,4 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +int timerlat_top_main(int argc, char *argv[]);
> +int timerlat_main(int argc, char *argv[]);
> diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c
> new file mode 100644
> index 000000000000..9764681ad8b1
> --- /dev/null
> +++ b/tools/tracing/rtla/src/timerlat_top.c
> @@ -0,0 +1,615 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
> + */
> +
> +#include <getopt.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <signal.h>
> +#include <unistd.h>
> +#include <stdio.h>
> +#include <time.h>
> +
> +#include "utils.h"
> +#include "osnoise.h"
> +#include "timerlat.h"
> +
> +struct timerlat_top_params {
> + char *cpus;
> + char *monitored_cpus;
> + char *trace_output;
> + unsigned long long runtime;
> + long long stop_us;
> + long long stop_total_us;
> + long long timerlat_period_us;
> + long long print_stack;
> + int sleep_time;
> + int output_divisor;
> + int duration;
> + int quiet;
> + int set_sched;
> + struct sched_attr sched_param;
> +};
> +
> +struct timerlat_top_cpu {
> + int irq_count;
> + int thread_count;
> +
> + unsigned long long cur_irq;
> + unsigned long long min_irq;
> + unsigned long long sum_irq;
> + unsigned long long max_irq;
> +
> + unsigned long long cur_thread;
> + unsigned long long min_thread;
> + unsigned long long sum_thread;
> + unsigned long long max_thread;
> +};
> +
> +struct timerlat_top_data {
> + struct timerlat_top_cpu *cpu_data;
> + int nr_cpus;
> +};
> +
> +/*
> + * timerlat_free_top - free runtime data
> + */
> +static void
> +timerlat_free_top(struct timerlat_top_data *data)
> +{
> + free(data->cpu_data);
> + free(data);
> +}
> +
> +/*
> + * timerlat_alloc_histogram - alloc runtime data
> + */
> +static struct timerlat_top_data *timerlat_alloc_top(int nr_cpus)
> +{
> + struct timerlat_top_data *data;
> + int cpu;
> +
> + data = calloc(1, sizeof(*data));
> + if (!data)
> + return NULL;
> +
> + data->nr_cpus = nr_cpus;
> +
> + /* one set of histograms per CPU */
> + data->cpu_data = calloc(1, sizeof(*data->cpu_data) * nr_cpus);
> + if (!data->cpu_data)
> + goto cleanup;
> +
> + /* set the min to max */
> + for (cpu = 0; cpu < nr_cpus; cpu++) {
> + data->cpu_data[cpu].min_irq = ~0;
> + data->cpu_data[cpu].min_thread = ~0;
> + }
> +
> + return data;
> +
> +cleanup:
> + timerlat_free_top(data);
> + return NULL;
> +}
> +
> +/*
> + * timerlat_hist_update - record a new timerlat occurent on cpu, updating data
> + */
> +static void
> +timerlat_top_update(struct osnoise_tool *tool, int cpu,
> + unsigned long long thread,
> + unsigned long long latency)
> +{
> + struct timerlat_top_data *data = tool->data;
> + struct timerlat_top_cpu *cpu_data = &data->cpu_data[cpu];
> +
> + if (!thread) {
> + cpu_data->irq_count++;
> + cpu_data->cur_irq = latency;
> + update_min(&cpu_data->min_irq, &latency);
> + update_sum(&cpu_data->sum_irq, &latency);
> + update_max(&cpu_data->max_irq, &latency);
> + } else {
> + cpu_data->thread_count++;
> + cpu_data->cur_thread = latency;
> + update_min(&cpu_data->min_thread, &latency);
> + update_sum(&cpu_data->sum_thread, &latency);
> + update_max(&cpu_data->max_thread, &latency);
> + }
> +}
> +
> +/*
> + * timerlat_top_handler - this is the handler for timerlat tracer events
> + */
> +static int
> +timerlat_top_handler(struct trace_seq *s, struct tep_record *record,
> + struct tep_event *event, void *context)
> +{
> + struct trace_instance *trace = context;
> + unsigned long long latency, thread;
> + struct osnoise_tool *top;
> + int cpu = record->cpu;
> +
> + top = container_of(trace, struct osnoise_tool, trace);
> +
> + tep_get_field_val(s, event, "context", record, &thread, 1);
> + tep_get_field_val(s, event, "timer_latency", record, &latency, 1);
> +
> + timerlat_top_update(top, cpu, thread, latency);
> +
> + return 0;
> +}
> +
> +/*
> + * timerlat_top_header - print the header of the tool output
> + */
> +static void timerlat_top_header(struct osnoise_tool *top)
> +{
> + struct timerlat_top_params *params = top->params;
> + struct trace_seq *s = top->trace.seq;
> + char duration[26];
> +
> + get_duration(top->start_time, duration, sizeof(duration));
> +
> + trace_seq_printf(s, "\033[2;37;40m");
> + trace_seq_printf(s, " Timer Latency ");
> + trace_seq_printf(s, "\033[0;0;0m");
> + trace_seq_printf(s, "\n");
> +
> + trace_seq_printf(s, "%-6s | IRQ Timer Latency (%s) | Thread Timer Latency (%s)\n", duration,
> + params->output_divisor == 1 ? "ns" : "us",
> + params->output_divisor == 1 ? "ns" : "us");
> +
> + trace_seq_printf(s, "\033[2;30;47m");
> + trace_seq_printf(s, "CPU COUNT | cur min avg max | cur min avg max");
> + trace_seq_printf(s, "\033[0;0;0m");
> + trace_seq_printf(s, "\n");
> +}
> +
> +/*
> + * timerlat_top_print - prints the output of a given CPU
> + */
> +static void timerlat_top_print(struct osnoise_tool *top, int cpu)
> +{
> +
> + struct timerlat_top_params *params = top->params;
> + struct timerlat_top_data *data = top->data;
> + struct timerlat_top_cpu *cpu_data = &data->cpu_data[cpu];
> + int divisor = params->output_divisor;
> + struct trace_seq *s = top->trace.seq;
> +
> + if (divisor == 0)
> + return;
> +
> + /*
> + * Skip if no data is available: is this cpu offline?
> + */
> + if (!cpu_data->irq_count && !cpu_data->thread_count)
> + return;
> +
> + /*
> + * Unless trace is being lost, IRQ counter is always the max.
> + */
> + trace_seq_printf(s, "%3d #%-9d |", cpu, cpu_data->irq_count);
> +
> + if (!cpu_data->irq_count) {
> + trace_seq_printf(s, " - ");
> + trace_seq_printf(s, " - ");
> + trace_seq_printf(s, " - ");
> + trace_seq_printf(s, " - |");
> + } else {
> + trace_seq_printf(s, "%9llu ", cpu_data->cur_irq / params->output_divisor);
> + trace_seq_printf(s, "%9llu ", cpu_data->min_irq / params->output_divisor);
> + trace_seq_printf(s, "%9llu ", (cpu_data->sum_irq / cpu_data->irq_count) / divisor);
> + trace_seq_printf(s, "%9llu |", cpu_data->max_irq / divisor);
> + }
> +
> + if (!cpu_data->thread_count) {
> + trace_seq_printf(s, " - ");
> + trace_seq_printf(s, " - ");
> + trace_seq_printf(s, " - ");
> + trace_seq_printf(s, " -\n");
> + } else {
> + trace_seq_printf(s, "%9llu ", cpu_data->cur_thread / divisor);
> + trace_seq_printf(s, "%9llu ", cpu_data->min_thread / divisor);
> + trace_seq_printf(s, "%9llu ",
> + (cpu_data->sum_thread / cpu_data->thread_count) / divisor);
> + trace_seq_printf(s, "%9llu\n", cpu_data->max_thread / divisor);
> + }
> +}
> +
> +/*
> + * clear_terminal - clears the output terminal
> + */
> +static void clear_terminal(struct trace_seq *seq)
> +{
> + if (!config_debug)
> + trace_seq_printf(seq, "\033c");
> +}
> +
> +/*
> + * timerlat_print_stats - print data for all cpus
> + */
> +static void
> +timerlat_print_stats(struct timerlat_top_params *params, struct osnoise_tool *top)
> +{
> + struct trace_instance *trace = &top->trace;
> + static int nr_cpus = -1;
> + int i;
> +
> + if (nr_cpus == -1)
> + nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
> +
> + if (!params->quiet)
> + clear_terminal(trace->seq);
> +
> + timerlat_top_header(top);
> +
> + for (i = 0; i < nr_cpus; i++) {
> + if (params->cpus && !params->monitored_cpus[i])
> + continue;
> + timerlat_top_print(top, i);
> + }
> +
> + trace_seq_do_printf(trace->seq);
> + trace_seq_reset(trace->seq);
> +}
> +
> +/*
> + * timerlat_top_usage - prints timerlat top usage message
> + */
> +static void timerlat_top_usage(char *usage)
> +{
> + int i;
> +
> + static const char *const msg[] = {
> + "",
> + " usage: rtla timerlat [top] [-h] [-q] [-p us] [-i us] [-t us] [-s us] [-T[=file]] \\",
> + " [-c cpu-list] [-P priority]",
> + "",
> + " -h/--help: print this menu",
> + " -p/--period us: timerlat period in us",
> + " -i/--irq us: stop trace if the irq latency is higher than the argument in us",
> + " -T/--thread us: stop trace if the thread latency is higher than the argument in us",
> + " -s/--stack us: save the stack trace at the IRQ if a thread latency is higher than the argument in us",
> + " -c/--cpus cpus: run the tracer only on the given cpus -d/--duration time[m|h|d]: duration of the session in seconds",
> + " -t/--trace[=file]: save the stopped trace to [file|timerlat_trace.txt]",
> + " -n/--nano: display data in nanoseconds",
> + " -q/--quiet print only a summary at the end",
> + " -P/--priority o:prio|r:prio|f:prio|d:runtime:period : set scheduling parameters",
> + " o:prio - use SCHED_OTHER with prio",
> + " r:prio - use SCHED_RR with prio",
> + " f:prio - use SCHED_FIFO with prio",
> + " d:runtime[us|ms|s]:period[us|ms|s] - use SCHED_DEADLINE with runtime and period",
> + " in nanoseconds",
> + NULL,
> + };

About help usage msg.

[-t us] --> [-T us]
[-T=[file]] --> [-t[=file]]

[-d] [-D] [-n] lack in the head usage info 'usage: ...'

> +
> + if (usage)
> + fprintf(stderr, "%s\n", usage);
> +
> + fprintf(stderr, "rtla timerlat top: a per-cpu summary of the timer latency (version %s)\n",
> + VERSION);
> +
> + for (i = 0; msg[i]; i++)
> + fprintf(stderr, "%s\n", msg[i]);
> + exit(1);
> +}
> +

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