* [PATCH V3 0/2] rtla: Add hwnoise tool
@ 2023-02-07 21:48 Daniel Bristot de Oliveira
2023-02-07 21:48 ` [PATCH V3 1/2] " Daniel Bristot de Oliveira
2023-02-07 21:48 ` [PATCH V3 2/2] Documentation/rtla: Add hwnoise man page Daniel Bristot de Oliveira
0 siblings, 2 replies; 3+ messages in thread
From: Daniel Bristot de Oliveira @ 2023-02-07 21:48 UTC (permalink / raw)
To: Daniel Bristot de Oliveira, Steven Rostedt, Jonathan Corbet
Cc: Juri Lelli, Clark Williams, Bagas Sanjaya, linux-trace-devel,
linux-doc, linux-kernel
This series present a new tool inside rtla. It is named hwnoise.
hwnoise dispatches the osnoise tracer and displays a summary of the noise.
The difference is that it runs the tracer with the OSNOISE_IRQ_DISABLE
option set, thus only allowing only hardware-related noise, resulting in
a simplified output. hwnoise has the same features of osnoise.
An example of the tool's output:
# rtla hwnoise -c 1-5 -T 1 -d 10m -q
Hardware-related Noise
duration: 0 00:10:00 | time is in us
CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI
1 #599 599000000 138 99.99997 3 3 4 74
2 #599 599000000 85 99.99998 3 3 4 75
3 #599 599000000 86 99.99998 4 3 6 75
4 #599 599000000 81 99.99998 4 4 2 75
5 #599 599000000 85 99.99998 2 2 2 75
Changes from v2:
Consolidate patches 1/5 into a single one (Steven)
Change the osnoise option macro to code (Steven)
Changes from v1:
Add rtla-hwnoise to the rtla documentation index
(kernel test robot/Bagas Sanjaya)
Daniel Bristot de Oliveira (2):
rtla: Add hwnoise tool
Documentation/rtla: Add hwnoise man page
Documentation/tools/rtla/index.rst | 1 +
Documentation/tools/rtla/rtla-hwnoise.rst | 107 ++++++++++++++++++++
tools/tracing/rtla/Makefile | 2 +
tools/tracing/rtla/src/osnoise.c | 117 ++++++++++++++++++++++
tools/tracing/rtla/src/osnoise.h | 7 ++
tools/tracing/rtla/src/osnoise_top.c | 84 +++++++++++++---
tools/tracing/rtla/src/rtla.c | 4 +
7 files changed, 306 insertions(+), 16 deletions(-)
create mode 100644 Documentation/tools/rtla/rtla-hwnoise.rst
--
2.38.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH V3 1/2] rtla: Add hwnoise tool
2023-02-07 21:48 [PATCH V3 0/2] rtla: Add hwnoise tool Daniel Bristot de Oliveira
@ 2023-02-07 21:48 ` Daniel Bristot de Oliveira
2023-02-07 21:48 ` [PATCH V3 2/2] Documentation/rtla: Add hwnoise man page Daniel Bristot de Oliveira
1 sibling, 0 replies; 3+ messages in thread
From: Daniel Bristot de Oliveira @ 2023-02-07 21:48 UTC (permalink / raw)
To: Daniel Bristot de Oliveira, Steven Rostedt, Jonathan Corbet
Cc: Juri Lelli, Clark Williams, Bagas Sanjaya, linux-trace-devel,
linux-doc, linux-kernel
The hwnoise tool is a special mode for the osnoise top tool.
hwnoise dispatches the osnoise tracer and displays a summary of the noise.
The difference is that it runs the tracer with the OSNOISE_IRQ_DISABLE
option set, thus only allowing only hardware-related noise, resulting in
a simplified output. hwnoise has the same features of osnoise.
An example of the tool's output:
# rtla hwnoise -c 1-11 -T 1 -d 10m -q
Hardware-related Noise
duration: 0 00:10:00 | time is in us
CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI
1 #599 599000000 138 99.99997 3 3 4 74
2 #599 599000000 85 99.99998 3 3 4 75
3 #599 599000000 86 99.99998 4 3 6 75
4 #599 599000000 81 99.99998 4 4 2 75
5 #599 599000000 85 99.99998 2 2 2 75
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jonathan Corbet <corbet@lwn.net>
---
tools/tracing/rtla/Makefile | 2 +
tools/tracing/rtla/src/osnoise.c | 117 +++++++++++++++++++++++++++
tools/tracing/rtla/src/osnoise.h | 7 ++
tools/tracing/rtla/src/osnoise_top.c | 84 +++++++++++++++----
tools/tracing/rtla/src/rtla.c | 4 +
5 files changed, 198 insertions(+), 16 deletions(-)
diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
index 22e28b76f800..2456a399eb9a 100644
--- a/tools/tracing/rtla/Makefile
+++ b/tools/tracing/rtla/Makefile
@@ -119,6 +119,8 @@ install: doc_install
$(STRIP) $(DESTDIR)$(BINDIR)/rtla
@test ! -f $(DESTDIR)$(BINDIR)/osnoise || rm $(DESTDIR)$(BINDIR)/osnoise
ln -s rtla $(DESTDIR)$(BINDIR)/osnoise
+ @test ! -f $(DESTDIR)$(BINDIR)/hwnoise || rm $(DESTDIR)$(BINDIR)/hwnoise
+ ln -s rtla $(DESTDIR)$(BINDIR)/hwnoise
@test ! -f $(DESTDIR)$(BINDIR)/timerlat || rm $(DESTDIR)$(BINDIR)/timerlat
ln -s rtla $(DESTDIR)$(BINDIR)/timerlat
diff --git a/tools/tracing/rtla/src/osnoise.c b/tools/tracing/rtla/src/osnoise.c
index 4dee343909b1..3ca7a3853943 100644
--- a/tools/tracing/rtla/src/osnoise.c
+++ b/tools/tracing/rtla/src/osnoise.c
@@ -734,6 +734,113 @@ void osnoise_put_tracing_thresh(struct osnoise_context *context)
context->orig_tracing_thresh = OSNOISE_OPTION_INIT_VAL;
}
+static int osnoise_options_get_option(char *option)
+{
+ char *options = tracefs_instance_file_read(NULL, "osnoise/options", NULL);
+ char no_option[128];
+ int retval = 0;
+ char *opt;
+
+ if (!options)
+ return OSNOISE_OPTION_INIT_VAL;
+
+ /*
+ * Check first if the option is disabled.
+ */
+ snprintf(no_option, sizeof(no_option), "NO_%s", option);
+
+ opt = strstr(options, no_option);
+ if (opt)
+ goto out_free;
+
+ /*
+ * Now that it is not disabled, if the string is there, it is
+ * enabled. If the string is not there, the option does not exist.
+ */
+ opt = strstr(options, option);
+ if (opt)
+ retval = 1;
+ else
+ retval = OSNOISE_OPTION_INIT_VAL;
+
+out_free:
+ free(options);
+ return retval;
+}
+
+static int osnoise_options_set_option(char *option, bool onoff)
+{
+ char no_option[128];
+
+ if (onoff)
+ return tracefs_instance_file_write(NULL, "osnoise/options", option);
+
+ snprintf(no_option, sizeof(no_option), "NO_%s", option);
+
+ return tracefs_instance_file_write(NULL, "osnoise/options", no_option);
+}
+
+static int osnoise_get_irq_disable(struct osnoise_context *context)
+{
+ if (context->opt_irq_disable != OSNOISE_OPTION_INIT_VAL)
+ return context->opt_irq_disable;
+
+ if (context->orig_opt_irq_disable != OSNOISE_OPTION_INIT_VAL)
+ return context->orig_opt_irq_disable;
+
+ context->orig_opt_irq_disable = osnoise_options_get_option("OSNOISE_IRQ_DISABLE");
+
+ return context->orig_opt_irq_disable;
+}
+
+int osnoise_set_irq_disable(struct osnoise_context *context, bool onoff)
+{
+ int opt_irq_disable = osnoise_get_irq_disable(context);
+ int retval;
+
+ if (opt_irq_disable == OSNOISE_OPTION_INIT_VAL)
+ return -1;
+
+ if (opt_irq_disable == onoff)
+ return 0;
+
+ retval = osnoise_options_set_option("OSNOISE_IRQ_DISABLE", onoff);
+ if (retval < 0)
+ return -1;
+
+ context->opt_irq_disable = onoff;
+
+ return 0;
+}
+
+static void osnoise_restore_irq_disable(struct osnoise_context *context)
+{
+ int retval;
+
+ if (context->orig_opt_irq_disable == OSNOISE_OPTION_INIT_VAL)
+ return;
+
+ if (context->orig_opt_irq_disable == context->opt_irq_disable)
+ goto out_done;
+
+ retval = osnoise_options_set_option("OSNOISE_IRQ_DISABLE", context->orig_opt_irq_disable);
+ if (retval < 0)
+ err_msg("Could not restore original OSNOISE_IRQ_DISABLE option\n");
+
+out_done:
+ context->orig_opt_irq_disable = OSNOISE_OPTION_INIT_VAL;
+}
+
+static void osnoise_put_irq_disable(struct osnoise_context *context)
+{
+ osnoise_restore_irq_disable(context);
+
+ if (context->orig_opt_irq_disable == OSNOISE_OPTION_INIT_VAL)
+ return;
+
+ context->orig_opt_irq_disable = OSNOISE_OPTION_INIT_VAL;
+}
+
/*
* enable_osnoise - enable osnoise tracer in the trace_instance
*/
@@ -798,6 +905,9 @@ struct osnoise_context *osnoise_context_alloc(void)
context->orig_tracing_thresh = OSNOISE_OPTION_INIT_VAL;
context->tracing_thresh = OSNOISE_OPTION_INIT_VAL;
+ context->orig_opt_irq_disable = OSNOISE_OPTION_INIT_VAL;
+ context->opt_irq_disable = OSNOISE_OPTION_INIT_VAL;
+
osnoise_get_context(context);
return context;
@@ -824,6 +934,7 @@ void osnoise_put_context(struct osnoise_context *context)
osnoise_put_timerlat_period_us(context);
osnoise_put_print_stack(context);
osnoise_put_tracing_thresh(context);
+ osnoise_put_irq_disable(context);
free(context);
}
@@ -958,3 +1069,9 @@ int osnoise_main(int argc, char *argv[])
osnoise_usage(1);
exit(1);
}
+
+int hwnoise_main(int argc, char *argv[])
+{
+ osnoise_top_main(argc, argv);
+ exit(0);
+}
diff --git a/tools/tracing/rtla/src/osnoise.h b/tools/tracing/rtla/src/osnoise.h
index 04a4384cc544..4dcf22ccd704 100644
--- a/tools/tracing/rtla/src/osnoise.h
+++ b/tools/tracing/rtla/src/osnoise.h
@@ -38,6 +38,10 @@ struct osnoise_context {
/* -1 as init value because 0 is disabled */
long long orig_print_stack;
long long print_stack;
+
+ /* -1 as init value because 0 is off */
+ int orig_opt_irq_disable;
+ int opt_irq_disable;
};
/*
@@ -79,6 +83,8 @@ void osnoise_restore_print_stack(struct osnoise_context *context);
int osnoise_set_print_stack(struct osnoise_context *context,
long long print_stack);
+int osnoise_set_irq_disable(struct osnoise_context *context, bool onoff);
+
/*
* osnoise_tool - osnoise based tool definition.
*/
@@ -97,3 +103,4 @@ struct osnoise_tool *osnoise_init_trace_tool(char *tracer);
int osnoise_hist_main(int argc, char *argv[]);
int osnoise_top_main(int argc, char **argv);
int osnoise_main(int argc, char **argv);
+int hwnoise_main(int argc, char **argv);
diff --git a/tools/tracing/rtla/src/osnoise_top.c b/tools/tracing/rtla/src/osnoise_top.c
index 76479bfb2922..562f2e4b18c5 100644
--- a/tools/tracing/rtla/src/osnoise_top.c
+++ b/tools/tracing/rtla/src/osnoise_top.c
@@ -14,6 +14,11 @@
#include "osnoise.h"
#include "utils.h"
+enum osnoise_mode {
+ MODE_OSNOISE = 0,
+ MODE_HWNOISE
+};
+
/*
* osnoise top parameters
*/
@@ -32,6 +37,7 @@ struct osnoise_top_params {
int set_sched;
struct sched_attr sched_param;
struct trace_events *events;
+ enum osnoise_mode mode;
};
struct osnoise_top_cpu {
@@ -143,15 +149,23 @@ osnoise_top_handler(struct trace_seq *s, struct tep_record *record,
*/
static void osnoise_top_header(struct osnoise_tool *top)
{
+ struct osnoise_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, " Operating System Noise");
- trace_seq_printf(s, " ");
- trace_seq_printf(s, " ");
+ trace_seq_printf(s, " ");
+
+ if (params->mode == MODE_OSNOISE) {
+ trace_seq_printf(s, "Operating System Noise");
+ trace_seq_printf(s, " ");
+ } else if (params->mode == MODE_HWNOISE) {
+ trace_seq_printf(s, "Hardware-related Noise");
+ }
+
+ trace_seq_printf(s, " ");
trace_seq_printf(s, "\033[0;0;0m");
trace_seq_printf(s, "\n");
@@ -162,7 +176,14 @@ static void osnoise_top_header(struct osnoise_tool *top)
trace_seq_printf(s, " Noise ");
trace_seq_printf(s, " %% CPU Aval ");
trace_seq_printf(s, " Max Noise Max Single ");
- trace_seq_printf(s, " HW NMI IRQ Softirq Thread");
+ trace_seq_printf(s, " HW NMI");
+
+ if (params->mode == MODE_HWNOISE)
+ goto eol;
+
+ trace_seq_printf(s, " IRQ Softirq Thread");
+
+eol:
trace_seq_printf(s, "\033[0;0;0m");
trace_seq_printf(s, "\n");
}
@@ -181,6 +202,7 @@ static void clear_terminal(struct trace_seq *seq)
*/
static void osnoise_top_print(struct osnoise_tool *tool, int cpu)
{
+ struct osnoise_top_params *params = tool->params;
struct trace_seq *s = tool->trace.seq;
struct osnoise_top_cpu *cpu_data;
struct osnoise_top_data *data;
@@ -205,6 +227,12 @@ static void osnoise_top_print(struct osnoise_tool *tool, int cpu)
trace_seq_printf(s, "%12llu ", cpu_data->hw_count);
trace_seq_printf(s, "%12llu ", cpu_data->nmi_count);
+
+ if (params->mode == MODE_HWNOISE) {
+ trace_seq_printf(s, "\n");
+ return;
+ }
+
trace_seq_printf(s, "%12llu ", cpu_data->irq_count);
trace_seq_printf(s, "%12llu ", cpu_data->softirq_count);
trace_seq_printf(s, "%12llu\n", cpu_data->thread_count);
@@ -241,12 +269,12 @@ osnoise_print_stats(struct osnoise_top_params *params, struct osnoise_tool *top)
/*
* osnoise_top_usage - prints osnoise top usage message
*/
-void osnoise_top_usage(char *usage)
+static void osnoise_top_usage(struct osnoise_top_params *params, char *usage)
{
int i;
static const char * const msg[] = {
- " usage: rtla osnoise [top] [-h] [-q] [-D] [-d s] [-a us] [-p us] [-r us] [-s us] [-S us] \\",
+ " [-h] [-q] [-D] [-d s] [-a us] [-p us] [-r us] [-s us] [-S us] \\",
" [-T us] [-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] \\",
" [-c cpu-list] [-P priority]",
"",
@@ -277,9 +305,22 @@ void osnoise_top_usage(char *usage)
if (usage)
fprintf(stderr, "%s\n", usage);
- fprintf(stderr, "rtla osnoise top: a per-cpu summary of the OS noise (version %s)\n",
+ if (params->mode == MODE_OSNOISE) {
+ fprintf(stderr,
+ "rtla osnoise top: a per-cpu summary of the OS noise (version %s)\n",
VERSION);
+ fprintf(stderr, " usage: rtla osnoise [top]");
+ }
+
+ if (params->mode == MODE_HWNOISE) {
+ fprintf(stderr,
+ "rtla hwnoise: a summary of hardware-related noise (version %s)\n",
+ VERSION);
+
+ fprintf(stderr, " usage: rtla hwnoise");
+ }
+
for (i = 0; msg[i]; i++)
fprintf(stderr, "%s\n", msg[i]);
exit(1);
@@ -299,6 +340,9 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
if (!params)
exit(1);
+ if (strcmp(argv[0], "hwnoise") == 0)
+ params->mode = MODE_HWNOISE;
+
while (1) {
static struct option long_options[] = {
{"auto", required_argument, 0, 'a'},
@@ -345,7 +389,7 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
case 'c':
retval = parse_cpu_list(optarg, ¶ms->monitored_cpus);
if (retval)
- osnoise_top_usage("\nInvalid -c cpu list\n");
+ osnoise_top_usage(params, "\nInvalid -c cpu list\n");
params->cpus = optarg;
break;
case 'D':
@@ -354,7 +398,7 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
case 'd':
params->duration = parse_seconds_duration(optarg);
if (!params->duration)
- osnoise_top_usage("Invalid -D duration\n");
+ osnoise_top_usage(params, "Invalid -D duration\n");
break;
case 'e':
tevent = trace_event_alloc(optarg);
@@ -370,17 +414,17 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
break;
case 'h':
case '?':
- osnoise_top_usage(NULL);
+ osnoise_top_usage(params, NULL);
break;
case 'p':
params->period = get_llong_from_str(optarg);
if (params->period > 10000000)
- osnoise_top_usage("Period longer than 10 s\n");
+ osnoise_top_usage(params, "Period longer than 10 s\n");
break;
case 'P':
retval = parse_prio(optarg, ¶ms->sched_param);
if (retval == -1)
- osnoise_top_usage("Invalid -P priority");
+ osnoise_top_usage(params, "Invalid -P priority");
params->set_sched = 1;
break;
case 'q':
@@ -389,7 +433,7 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
case 'r':
params->runtime = get_llong_from_str(optarg);
if (params->runtime < 100)
- osnoise_top_usage("Runtime shorter than 100 us\n");
+ osnoise_top_usage(params, "Runtime shorter than 100 us\n");
break;
case 's':
params->stop_us = get_llong_from_str(optarg);
@@ -415,7 +459,7 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
exit(EXIT_FAILURE);
}
} else {
- osnoise_top_usage("--trigger requires a previous -e\n");
+ osnoise_top_usage(params, "--trigger requires a previous -e\n");
}
break;
case '1': /* filter */
@@ -426,11 +470,11 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
exit(EXIT_FAILURE);
}
} else {
- osnoise_top_usage("--filter requires a previous -e\n");
+ osnoise_top_usage(params, "--filter requires a previous -e\n");
}
break;
default:
- osnoise_top_usage("Invalid option");
+ osnoise_top_usage(params, "Invalid option");
}
}
@@ -495,6 +539,14 @@ osnoise_top_apply_config(struct osnoise_tool *tool, struct osnoise_top_params *p
}
}
+ if (params->mode == MODE_HWNOISE) {
+ retval = osnoise_set_irq_disable(tool->context, 1);
+ if (retval) {
+ err_msg("Failed to set OSNOISE_IRQ_DISABLE option\n");
+ goto out_err;
+ }
+ }
+
return 0;
out_err:
diff --git a/tools/tracing/rtla/src/rtla.c b/tools/tracing/rtla/src/rtla.c
index 52e8f1825281..7635c70123ab 100644
--- a/tools/tracing/rtla/src/rtla.c
+++ b/tools/tracing/rtla/src/rtla.c
@@ -26,6 +26,7 @@ static void rtla_usage(int err)
"",
" commands:",
" osnoise - gives information about the operating system noise (osnoise)",
+ " hwnoise - gives information about hardware-related noise",
" timerlat - measures the timer irq and thread latency",
"",
NULL,
@@ -47,6 +48,9 @@ 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], "hwnoise") == 0) {
+ hwnoise_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;
--
2.38.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH V3 2/2] Documentation/rtla: Add hwnoise man page
2023-02-07 21:48 [PATCH V3 0/2] rtla: Add hwnoise tool Daniel Bristot de Oliveira
2023-02-07 21:48 ` [PATCH V3 1/2] " Daniel Bristot de Oliveira
@ 2023-02-07 21:48 ` Daniel Bristot de Oliveira
1 sibling, 0 replies; 3+ messages in thread
From: Daniel Bristot de Oliveira @ 2023-02-07 21:48 UTC (permalink / raw)
To: Daniel Bristot de Oliveira, Steven Rostedt, Jonathan Corbet
Cc: Juri Lelli, Clark Williams, Bagas Sanjaya, linux-trace-devel,
linux-doc, linux-kernel
Add a man page for the new rtla hwnoise tool, mostly based in the
rtla osnoise top.
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jonathan Corbet <corbet@lwn.net>
---
Documentation/tools/rtla/index.rst | 1 +
Documentation/tools/rtla/rtla-hwnoise.rst | 107 ++++++++++++++++++++++
2 files changed, 108 insertions(+)
create mode 100644 Documentation/tools/rtla/rtla-hwnoise.rst
diff --git a/Documentation/tools/rtla/index.rst b/Documentation/tools/rtla/index.rst
index 840f0bf3e803..05d2652e4072 100644
--- a/Documentation/tools/rtla/index.rst
+++ b/Documentation/tools/rtla/index.rst
@@ -17,6 +17,7 @@ behavior on specific hardware.
rtla-timerlat
rtla-timerlat-hist
rtla-timerlat-top
+ rtla-hwnoise
.. only:: subproject and html
diff --git a/Documentation/tools/rtla/rtla-hwnoise.rst b/Documentation/tools/rtla/rtla-hwnoise.rst
new file mode 100644
index 000000000000..fb1c52bbc00b
--- /dev/null
+++ b/Documentation/tools/rtla/rtla-hwnoise.rst
@@ -0,0 +1,107 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============
+rtla-hwnoise
+============
+------------------------------------------
+Detect and quantify hardware-related noise
+------------------------------------------
+
+:Manual section: 1
+
+SYNOPSIS
+========
+
+**rtla hwnoise** [*OPTIONS*]
+
+DESCRIPTION
+===========
+
+**rtla hwnoise** collects the periodic summary from the *osnoise* tracer
+running with *interrupts disabled*. By disabling interrupts, and the scheduling
+of threads as a consequence, only non-maskable interrupts and hardware-related
+noise is allowed.
+
+The tool also allows the configurations of the *osnoise* tracer and the
+collection of the tracer output.
+
+OPTIONS
+=======
+.. include:: common_osnoise_options.rst
+
+.. include:: common_top_options.rst
+
+.. include:: common_options.rst
+
+EXAMPLE
+=======
+In the example below, the **rtla hwnoise** tool is set to run on CPUs *1-7*
+on a system with 8 cores/16 threads with hyper-threading enabled.
+
+The tool is set to detect any noise higher than *one microsecond*,
+to run for *ten minutes*, displaying a summary of the report at the
+end of the session::
+
+ # rtla hwnoise -c 1-7 -T 1 -d 10m -q
+ Hardware-related Noise
+ duration: 0 00:10:00 | time is in us
+ CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI
+ 1 #599 599000000 138 99.99997 3 3 4 74
+ 2 #599 599000000 85 99.99998 3 3 4 75
+ 3 #599 599000000 86 99.99998 4 3 6 75
+ 4 #599 599000000 81 99.99998 4 4 2 75
+ 5 #599 599000000 85 99.99998 2 2 2 75
+ 6 #599 599000000 76 99.99998 2 2 0 75
+ 7 #599 599000000 77 99.99998 3 3 0 75
+
+
+The first column shows the *CPU*, and the second column shows how many
+*Periods* the tool ran during the session. The *Runtime* is the time
+the tool effectively runs on the CPU. The *Noise* column is the sum of
+all noise that the tool observed, and the *% CPU Aval* is the relation
+between the *Runtime* and *Noise*.
+
+The *Max Noise* column is the maximum hardware noise the tool detected in a
+single period, and the *Max Single* is the maximum single noise seen.
+
+The *HW* and *NMI* columns show the total number of *hardware* and *NMI* noise
+occurrence observed by the tool.
+
+For example, *CPU 3* ran *599* periods of *1 second Runtime*. The CPU received
+*86 us* of noise during the entire execution, leaving *99.99997 %* of CPU time
+for the application. In the worst single period, the CPU caused *4 us* of
+noise to the application, but it was certainly caused by more than one single
+noise, as the *Max Single* noise was of *3 us*. The CPU has *HW noise,* at a
+rate of *six occurrences*/*ten minutes*. The CPU also has *NMIs*, at a higher
+frequency: around *seven per second*.
+
+The tool should report *0* hardware-related noise in the ideal situation.
+For example, by disabling hyper-threading to remove the hardware noise,
+and disabling the TSC watchdog to remove the NMI (it is possible to identify
+this using tracing options of **rtla hwnoise**), it was possible to reach
+the ideal situation in the same hardware::
+
+ # rtla hwnoise -c 1-7 -T 1 -d 10m -q
+ Hardware-related Noise
+ duration: 0 00:10:00 | time is in us
+ CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI
+ 1 #599 599000000 0 100.00000 0 0 0 0
+ 2 #599 599000000 0 100.00000 0 0 0 0
+ 3 #599 599000000 0 100.00000 0 0 0 0
+ 4 #599 599000000 0 100.00000 0 0 0 0
+ 5 #599 599000000 0 100.00000 0 0 0 0
+ 6 #599 599000000 0 100.00000 0 0 0 0
+ 7 #599 599000000 0 100.00000 0 0 0 0
+
+SEE ALSO
+========
+
+**rtla-osnoise**\(1)
+
+Osnoise tracer documentation: <https://www.kernel.org/doc/html/latest/trace/osnoise-tracer.html>
+
+AUTHOR
+======
+Written by Daniel Bristot de Oliveira <bristot@kernel.org>
+
+.. include:: common_appendix.rst
--
2.38.1
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