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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-09-13 12:27:00 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-09-13 12:27:00 -0700 |
| commit | 22098763a10d9c1340827fcf6edab66f153b27f0 (patch) | |
| tree | 3962f95a34df034652ff93686cdd156c7197f2d9 /Documentation/tools/rtla | |
| download | linux-stable-22098763a10d9c1340827fcf6edab66f153b27f0.tar.gz linux-stable-22098763a10d9c1340827fcf6edab66f153b27f0.zip | |
Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted
Pull tracing fixes from Steven Rostedt:
- Don't destroy user event fields when removal fails
User event fields are destroyed before the event is removed from
visibility. But that can fail leaving the still visible event with no
fields. Move the destroying of the fields to after the event is
successfully removed from visibility.
- Initialize function graph state is fork before calling
copy_exec_state()
For non-CLONE_VM forks, copy_exec_state() allocates a new
task_exec_state. If that allocation fails, ftrace_graph_exit_task()
will free the tasks ret_stack pointer. Since that pointer is still
using the parent's ret_stack, it mistakenly frees the parent's
pointer too.
Call ftrace_graph_init() on the task first which will NULL out the
new tasks's ret_stack and if the copy fails, it will not free
anything.
- Remove FGRAPH_MAX_INDEX
The macro FGRAPH_MAX_INDEX was added but never used. Remove it.
- Save ent_size in function graph printing of nested functions
The function graph tracer needs to look at the next event to see if
the next event is the return of the current function entry. If it is,
it prints a single line:
ktime_get();
Otherwise it prints it like a nested function:
tick_nohz_irq_exit() {
ktime_get();
kcpustat_irq_exit();
}
In order to look at the next event, it must save the current event so
that it has the information to print from it. It saves the event in
the iterator descriptor called "ent". What it doesn't save is the
ent_size of the event which is now used to know if the function graph
arguments are to be printed. The peek doesn't save the size so the
size used happens to be that of the size of the last event that was
seen.
Save the entry event size in the iterator descriptor so that the
correct size is used.
- Fix several errors with freeing data in the histogram code
The histogram code had a lot of leaked or or incorrect accounting
when failures happen. Correct them.
- Fix histogram regression of .percent and .graph modifiers
Up until 6.3 histogram values could have "percent" or "graph"
modifiers that changed how they were printed. But a change that added
restricting histograms values from being strings, stack traces and
other modifiers inadvertently prevented them from using the percent
and graph modifiers, which were legal use cases for values.
Put back the percent and graph modifiers.
- Fix various typos in the comments
- Set the trace_clock before initializing a histogram with clock
argument
The histogram API allows the user to specific which trace clock to
use via a "clock=" string. The histogram is set up first before the
clock is checked. If the passed in clock is not valid, it exits
without fully fixing up the histogram leaving it on the list and a
use-after-free can trigger.
Update the clock argument first and if it fails then exit gracefully
before the histogram trigger is placed on any lists.
- Restore :mod: trailer after parsing in ftrace_set_clr_event
The function ftrace_set_clr_event() modifies the parse string and
needs to put it back to what was passed in. It searches for ":mod:"
via a strsep() but fails to put back the first ':' in the string.
Add back the ':' in the passed in string.
- Take trace_array reference when opening a tracer options file
The options files are dynamically created and some tracers add their
own options. When a tracer adds their own list of options, the
trace_array holding them has an array to hold the list of options for
each tracer. This array increases in size via a krealloc(), and the
new entry gets a newly allocated array to hold the options of the new
tracer being added.
The element in each entry of the tracer's option array holds a
pointer back to the trace_array, a pointer to the tracer it is
associated to, a pointer to the flags of the option.
The issue is that these arrays are freed when the trace_array is
freed when its instance it represents is removed from the instances
directory. There's a race that an open of one of these options files
can happen when the instance is being removed.
Add a new helper function to be called by the open function of the
options file to iterate all existing trace_arrays under a lock and
find the one that has the given option element in one of it's tracer
arrays. If found, then update the associated trace_array's reference
counter to keep it from being freed. If not found, have the open call
return -ENODEV.
- Disable interrupts when acquiring the lock in rb_wake_up_waiters()
The function rb_wake_up_waiters() assumes it will be called in
interrupt context and does not disable irqs when taking
cpu_buffer->reader_lock, which can be called in hard interrupt
context. The issue is in PREEMPT_RT, this function is called in
thread context leaving this lock open to a deadlock.
Take the lock with interrupts disabled.
- Use rcu_assign_pointer() for tmp_ops filter hash
The tmp_ops used in update_ftrace_direct_mod() assigns its
filter_hash field directly, but that field is annotated as __rcu and
sparse complains. Assign it with rcu_assign_pointer()
- Fix use-after-free in enable_trigger_private_data_free()
The trace_event_call is accessed through the event_trigger_data's
trace_event_file pointer to put the trace_event_call on freeing. The
issue is that the trace_event_file data may have been freed already
causing a use-after-free. Add a field to the event_trigger_data that
points directly to the trace_event_call so that it can decrement its
reference directly without needing to go through the
trace_event_file.
- Fix accounting of buffer data remote headers
trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
the number of pages is needed for the asked for size as it doesn't
take into account the meta data on each page. Add a helper function
to do the calculation properly and use that in these functions.
- Catch nr_page_va overflow in ring_buffer_desc sizing
The number of pages per remote ring buffer is capped by
ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
overflow that field would silently allocate a descriptor smaller than
what was asked for.
- Do not resize the subbuf order if any per_cpu buffer is disabled
The mmapping of ring buffers disables resizing the subbuffers, but it
is done per-cpu whereas the subbuf size change is done for all the
per_cpu buffers under the buffer->mutex. It could change the size of
some while the mapping is happening on others. Have the resize of the
subbuf order check all the per_cpu buffers under the lock to see if
any of them is disabled before starting and causing an inconsistency
between buffers that are being mapped.
* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
ring-buffer: Check resize_disabled before publishing the new subbuf order
tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
tracing/remotes: Account for ring buffer page header in size calculation
tracing: Don't dereference trace_event_file in deferred trigger free
ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
tracing: Take trace_array reference when opening a tracer options file
tracing: Fix ring_buffer_read_page_size() kernel-doc
tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
tracing: Fix memory corruption from a "STACKTRACE" histogram key
tracing: Fix memory corruption from the histogram stacktrace modifier
tracing: Undo the registration when enabling the histogram trigger fails
tracing: Take the reference before publishing the named histogram trigger
tracing: Set the trace clock before registering the histogram trigger
tracing: Fix typo "preceeded" in comment
tracing: Fix typo "availabe" in comment
tracing: Let histogram values keep the percent and graph modifiers
tracing: Keep the entry count when the histogram stats allocation fails
tracing: Free histogram the field rejected for a bad modifier
tracing: Free histogram the var ref when its initialization fails
...
Diffstat (limited to 'Documentation/tools/rtla')
19 files changed, 1144 insertions, 0 deletions
diff --git a/Documentation/tools/rtla/Makefile b/Documentation/tools/rtla/Makefile new file mode 100644 index 000000000..093af6d7a --- /dev/null +++ b/Documentation/tools/rtla/Makefile @@ -0,0 +1,53 @@ +# SPDX-License-Identifier: GPL-2.0-only +# Based on bpftool's Documentation Makefile + +INSTALL ?= install +RM ?= rm -f +RMDIR ?= rmdir --ignore-fail-on-non-empty + +PREFIX ?= /usr/share +MANDIR ?= $(PREFIX)/man +MAN1DIR = $(MANDIR)/man1 + +MAN1_RST = $(wildcard rtla*.rst) + +_DOC_MAN1 = $(patsubst %.rst,%.1,$(MAN1_RST)) +DOC_MAN1 = $(addprefix $(OUTPUT),$(_DOC_MAN1)) + +RST2MAN_DEP := $(shell command -v rst2man 2>/dev/null) +RST2MAN_OPTS += --verbose + +TEST_RST2MAN = $(shell sh -c "rst2man --version > /dev/null 2>&1 || echo n") + +$(OUTPUT)%.1: %.rst +ifndef RST2MAN_DEP + $(info ********************************************) + $(info ** NOTICE: rst2man not found) + $(info **) + $(info ** Consider installing the latest rst2man from your) + $(info ** distribution, e.g., 'dnf install python3-docutils' on Fedora,) + $(info ** or from source:) + $(info **) + $(info ** https://docutils.sourceforge.io/docs/dev/repository.html ) + $(info **) + $(info ********************************************) + $(error NOTICE: rst2man required to generate man pages) +endif + rst2man $(RST2MAN_OPTS) $< > $@ + +man1: $(DOC_MAN1) +man: man1 + +clean: + $(RM) $(DOC_MAN1) + +install: man + $(INSTALL) -d -m 755 $(DESTDIR)$(MAN1DIR) + $(INSTALL) -m 644 $(DOC_MAN1) $(DESTDIR)$(MAN1DIR) + +uninstall: + $(RM) $(addprefix $(DESTDIR)$(MAN1DIR)/,$(_DOC_MAN1)) + $(RMDIR) $(DESTDIR)$(MAN1DIR) + +.PHONY: man man1 clean install uninstall +.DEFAULT_GOAL := man diff --git a/Documentation/tools/rtla/common_appendix.txt b/Documentation/tools/rtla/common_appendix.txt new file mode 100644 index 000000000..ad610ed02 --- /dev/null +++ b/Documentation/tools/rtla/common_appendix.txt @@ -0,0 +1,63 @@ +.. SPDX-License-Identifier: GPL-2.0 + +UNSETTING OPTIONS +================= + +The effect of most command line options can be reverted by prepending "no-" to +the long variant of the option, for example: + +$ rtla timerlat top -p 100 --no-period + +resets the period back to the default value of 1000 us. + +If a command line option sets multiple RTLA parameters at once, the inverted +option will revert all of them, even if they were not set by the particular +option. For example, since using "--auto" implies "--trace", specifying +"--trace --no-auto" will also disable trace output, just like if "--no-trace" +was specified. + + +SIGINT BEHAVIOR +=============== + +On the first SIGINT, RTLA exits after collecting all outstanding samples up to +the point of receiving the signal. + +When receiving more than one SIGINT, RTLA discards any outstanding samples, and +exits while displaying only samples that have already been processed. + +If SIGINT is received during RTLA cleanup, RTLA exits immediately via +the default signal handler. + +Note: For the purpose of SIGINT behavior, the expiry of duration specified via +the -d/--duration option is treated as equivalent to receiving a SIGINT. For +example, a SIGINT received after duration expired but samples have not been +processed yet will drop any outstanding samples. + +Also note that when using the timerlat tool in BPF mode, samples are processed +in-kernel; RTLA only copies them out to display them to the user. A second +SIGINT does not affect in-kernel sample aggregation. + +EXIT STATUS +=========== + +:: + + 0 Passed: the test did not hit the stop tracing condition + 1 Error: invalid argument + 2 Failed: the test hit the stop tracing condition + 129 Help: either user requested help or incorrect option was specified + +REPORTING BUGS +============== +Report bugs to <linux-kernel@vger.kernel.org> +and <linux-trace-devel@vger.kernel.org> + +LICENSE +======= +**rtla** is Free Software licensed under the GNU GPLv2 + +COPYING +======= +Copyright \(C) 2021 Red Hat, Inc. Free use of this software is granted under +the terms of the GNU Public License (GPL). diff --git a/Documentation/tools/rtla/common_hist_options.txt b/Documentation/tools/rtla/common_hist_options.txt new file mode 100644 index 000000000..df53ff835 --- /dev/null +++ b/Documentation/tools/rtla/common_hist_options.txt @@ -0,0 +1,23 @@ +**-b**, **--bucket-size** *N* + + Set the histogram bucket size (default *1*). + +**-E**, **--entries** *N* + + Set the number of entries of the histogram (default 256). + +**--no-header** + + Do not print header. + +**--no-summary** + + Do not print summary. + +**--no-index** + + Do not print index. + +**--with-zeros** + + Print zero only entries. diff --git a/Documentation/tools/rtla/common_options.txt b/Documentation/tools/rtla/common_options.txt new file mode 100644 index 000000000..38da1cf44 --- /dev/null +++ b/Documentation/tools/rtla/common_options.txt @@ -0,0 +1,140 @@ +**-c**, **--cpus** *cpu-list* + + Set the |tool| tracer to run the sample threads in the cpu-list. + + By default, the |tool| tracer runs the sample threads on all CPUs. + +**-H**, **--house-keeping** *cpu-list* + + Run rtla control threads only on the given cpu-list. + + If omitted, rtla will attempt to auto-migrate its main thread to any CPU that is not running any workload threads. + +**-d**, **--duration** *time[s|m|h|d]* + + Set the duration of the session. + +**-D**, **--debug** + + Print debug info. + +**-e**, **--event** *sys:event* + + Enable an event in the trace (**-t**) session. The argument can be a specific event, e.g., **-e** *sched:sched_switch*, or all events of a system group, e.g., **-e** *sched*. Multiple **-e** are allowed. It is only active when **-t** or **-a** are set. + + This option cannot be unset. + +**--filter** *<filter>* + + Filter the previous **-e** *sys:event* event with *<filter>*. For further information about event filtering see https://www.kernel.org/doc/html/latest/trace/events.html#event-filtering. + + This option cannot be unset. + +**--trigger** *<trigger>* + Enable a trace event trigger to the previous **-e** *sys:event*. + If the *hist:* trigger is activated, the output histogram will be automatically saved to a file named *system_event_hist.txt*. + For example, the command: + + rtla <command> <mode> -t -e osnoise:irq_noise --trigger="hist:key=desc,duration/1000:sort=desc,duration/1000:vals=hitcount" + + Will automatically save the content of the histogram associated to *osnoise:irq_noise* event in *osnoise_irq_noise_hist.txt*. + + For further information about event trigger see https://www.kernel.org/doc/html/latest/trace/events.html#event-triggers. + + This option cannot be unset. + +**-P**, **--priority** *o:prio|r:prio|f:prio|d:runtime:period* + + Set scheduling parameters to the |tool| tracer threads, the format to set the priority are: + + - *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. + + If not set, tracer threads keep their default priority. For rtla user threads, it is set to SCHED_FIFO with priority 95. For kernel threads, see *osnoise* and *timerlat* tracer documentation for the running kernel version. + +**-C**, **--cgroup** \[*cgroup*] + + Set a *cgroup* to the tracer's threads. If the **-C** option is passed without arguments, the tracer's thread will inherit **rtla**'s *cgroup*. Otherwise, the threads will be placed on the *cgroup* passed to the option. + + If not set, the behavior differs between workload types. User workloads created by rtla will inherit rtla's cgroup. Kernel workloads are assigned the root cgroup. + +**--warm-up** *s* + + After starting the workload, let it run for *s* seconds before starting collecting the data, allowing the system to warm-up. Statistical data generated during warm-up is discarded. + +**--trace-buffer-size** *kB* + Set the per-cpu trace buffer size in kB for the tracing output. + + If not set, the default tracefs buffer size is used. + +**--on-threshold** *action* + + Defines an action to be executed when tracing is stopped on a latency threshold + specified by |threshold|. + + Multiple --on-threshold actions may be specified, and they will be executed in + the order they are provided. If any action fails, subsequent actions in the list + will not be executed. + + Supported actions are: + + - *trace[,file=<filename>]* + + Saves trace output, optionally taking a filename. Alternative to -t/--trace. + Note that unlike -t/--trace, specifying this multiple times will result in + the trace being saved multiple times, and --no-trace will not disable trace + output when enabled through this option. + + - *signal,num=<sig>,pid=<pid>* + + Sends signal to process. "parent" might be specified in place of pid to target + the parent process of rtla. + + - *shell,command=<command>* + + Execute shell command. + + - *continue* + + Continue tracing after actions are executed instead of stopping. + + Example: + + $ rtla |tool| |thresharg| 20 --on-threshold trace + --on-threshold shell,command="grep ipi_send |tracer|\_trace.txt" + --on-threshold signal,num=2,pid=parent + + This will save a trace with the default filename "|tracer|\_trace.txt", print its + lines that contain the text "ipi_send" on standard output, and send signal 2 + (SIGINT) to the parent process. + + Performance Considerations: + + |actionsperf| + + This option cannot be unset. + +**--on-end** *action* + + Defines an action to be executed at the end of tracing. + + Multiple --on-end actions can be specified, and they will be executed in the order + they are provided. If any action fails, subsequent actions in the list will not be + executed. + + See the documentation for **--on-threshold** for the list of supported actions, with + the exception that *continue* has no effect. + + Example: + + $ rtla |tool| -d 5s --on-end trace + + This runs rtla with the default options, and saves trace output at the end. + + This option cannot be unset. + +**-h**, **--help** + + Print help menu. diff --git a/Documentation/tools/rtla/common_osnoise_description.txt b/Documentation/tools/rtla/common_osnoise_description.txt new file mode 100644 index 000000000..d5d61615b --- /dev/null +++ b/Documentation/tools/rtla/common_osnoise_description.txt @@ -0,0 +1,8 @@ +The **rtla osnoise** tool is an interface for the *osnoise* tracer. The +*osnoise* tracer dispatches a kernel thread per-cpu. These threads read the +time in a loop while with preemption, softirq and IRQs enabled, thus +allowing all the sources of operating system noise during its execution. +The *osnoise*'s tracer threads take note of the delta between each time +read, along with an interference counter of all sources of interference. +At the end of each period, the *osnoise* tracer displays a summary of +the results. diff --git a/Documentation/tools/rtla/common_osnoise_options.txt b/Documentation/tools/rtla/common_osnoise_options.txt new file mode 100644 index 000000000..5fc70c001 --- /dev/null +++ b/Documentation/tools/rtla/common_osnoise_options.txt @@ -0,0 +1,43 @@ +.. |threshold| replace:: **-a/--auto**, **-s/--stop**, or **-S/--stop-total** +.. |thresharg| replace:: -s +.. |tracer| replace:: osnoise + +.. |actionsperf| replace:: + Due to implementational limitations, actions might be delayed + up to one second after tracing is stopped. + +**-a**, **--auto** *us* + + Set the automatic trace mode. This mode sets some commonly used options + while debugging the system. It is equivalent to use **-s** *us* **-T 1 -t**. + +**-p**, **--period** *us* + + Set the *osnoise* tracer period in microseconds. + +**-r**, **--runtime** *us* + + Set the *osnoise* tracer runtime in microseconds. + +**-s**, **--stop** *us* + + Stop the trace if a single sample is higher than the argument in microseconds. + If **-T** is set, it will also save the trace to the output. + + This option cannot be unset. + +**-S**, **--stop-total** *us* + + Stop the trace if the total sample is higher than the argument in microseconds. + If **-T** is set, it will also save the trace to the output. + + This option cannot be unset. + +**-T**, **--threshold** *us* + + Specify the minimum delta between two time reads to be considered noise. + The default threshold is *5 us*. + +**-t**, **--trace** \[*file*] + + Save the stopped trace to [*file|osnoise_trace.txt*]. diff --git a/Documentation/tools/rtla/common_timerlat_aa.txt b/Documentation/tools/rtla/common_timerlat_aa.txt new file mode 100644 index 000000000..077029e6b --- /dev/null +++ b/Documentation/tools/rtla/common_timerlat_aa.txt @@ -0,0 +1,7 @@ +**--dump-tasks** + + prints the task running on all CPUs if stop conditions are met (depends on !--no-aa) + +**--no-aa** + + disable auto-analysis, reducing rtla timerlat cpu usage diff --git a/Documentation/tools/rtla/common_timerlat_description.txt b/Documentation/tools/rtla/common_timerlat_description.txt new file mode 100644 index 000000000..49fcae3ff --- /dev/null +++ b/Documentation/tools/rtla/common_timerlat_description.txt @@ -0,0 +1,18 @@ +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 enables the trace of the most relevant information via +**osnoise:** tracepoints. + +The **rtla timerlat** tool sets the options of the *timerlat* tracer +and collects and displays a summary of the results. By default, +the collection is done synchronously in kernel space using a dedicated +BPF program attached to the *timerlat* tracer. If either BPF or +the **osnoise:timerlat_sample** tracepoint it attaches to is +unavailable, the **rtla timerlat** tool falls back to using tracefs to +process the data asynchronously in user space. diff --git a/Documentation/tools/rtla/common_timerlat_options.txt b/Documentation/tools/rtla/common_timerlat_options.txt new file mode 100644 index 000000000..e36898438 --- /dev/null +++ b/Documentation/tools/rtla/common_timerlat_options.txt @@ -0,0 +1,112 @@ +.. |threshold| replace:: **-a/--auto**, **-i/--irq**, or **-T/--thread** +.. |thresharg| replace:: -T +.. |tracer| replace:: timerlat + +.. |actionsperf| replace:: + For time-sensitive actions, it is recommended to run **rtla timerlat** with BPF + support and RT priority. Note that due to implementational limitations, actions + might be delayed up to one second after tracing is stopped if BPF mode is not + available or disabled. + +**-a**, **--auto** *us* + + Set the automatic trace mode. This mode sets some commonly used options + while debugging the system. It is equivalent to use **-T** *us* **-s** *us* + **-t**. By default, *timerlat* tracer uses FIFO:95 for *timerlat* threads, + thus equivalent to **-P** *f:95*. + +**-p**, **--period** *us* + + Set the *timerlat* tracer period in microseconds. + +**-i**, **--irq** *us* + + Stop trace if the *IRQ* latency is higher than the argument in us. + + This option cannot be unset. + +**-T**, **--thread** *us* + + Stop trace if the *Thread* latency is higher than the argument in us. + + This option cannot be unset. + +**-s**, **--stack** *us* + + Save the stack trace at the *IRQ* if a *Thread* latency is higher than the + argument in us. + +**-t**, **--trace** \[*file*] + + Save the stopped trace to [*file|timerlat_trace.txt*]. + +**--dma-latency** *us* + Set the /dev/cpu_dma_latency to *us*, aiming to bound exit from idle latencies. + *cyclictest* sets this value to *0* by default, use **--dma-latency** *0* to have + similar results. + +**--deepest-idle-state** *n* + Disable idle states higher than *n* for cpus that are running timerlat threads to + reduce exit from idle latencies. If *n* is -1, all idle states are disabled. + On exit from timerlat, the idle state setting is restored to its original state + before running timerlat. + + Requires rtla to be built with libcpupower. + +**-k**, **--kernel-threads** + + Use timerlat kernel-space threads, in contrast of **-u**. + +**-u**, **--user-threads** + + Set timerlat to run without a workload, and then dispatches user-space workloads + to wait on the timerlat_fd. Once the workload is awakened, it goes to sleep again + adding so the measurement for the kernel-to-user and user-to-kernel to the tracer + output. **--user-threads** will be used unless the user specify **-k**. + +**-U**, **--user-load** + + Set timerlat to run without workload, waiting for the user to dispatch a per-cpu + task that waits for a new period on the tracing/osnoise/per_cpu/cpu$ID/timerlat_fd. + See linux/tools/rtla/example/timerlat_load.py for an example of user-load code. + +**--bpf-action** *bpf-program* + + Loads a BPF program from an ELF file and executes it when a latency threshold is exceeded. + + The BPF program must be a valid ELF file loadable with libbpf. The program must contain + a function named ``action_handler``, stored in an ELF section with the ``tp_`` prefix. + The prefix is used by libbpf to set BPF program type to BPF_PROG_TYPE_TRACEPOINT. + + The program receives a ``struct trace_event_raw_timerlat_sample`` parameter + containing timerlat sample data. + + An example is provided in ``tools/tracing/rtla/example/timerlat_bpf_action.c``. + This example demonstrates how to create a BPF program that prints latency information using + bpf_trace_printk() when a threshold is exceeded. + + **Note**: BPF actions require BPF support to be available. If BPF is not available + or disabled, the tool falls back to tracefs mode and BPF actions are not supported. + +**--stack-format** *format* + + Adjust the format of the stack trace printed during auto-analysis. + + The supported values for *format* are: + + * **truncate** Print the stack trace up to the first unknown address (default). + * **skip** Skip unknown addresses. + * **full** Print the entire stack trace, including unknown addresses. + + For unknown addresses, the raw pointer is printed. + +**-A**, **--aligned** *us* + + Align wake-up of timerlat threads to a set offset in microseconds. + + The alignment will be applied when the threads wake up at the start of tracing while + the timer for the first cycle is armed. Each thread sets its timer to the wake-up time + of the previous thread plus the alignment. + + This option may be used with any non-negative argument, including zero, which will + align threads so that they wake up all at the same time. diff --git a/Documentation/tools/rtla/common_top_options.txt b/Documentation/tools/rtla/common_top_options.txt new file mode 100644 index 000000000..f48878938 --- /dev/null +++ b/Documentation/tools/rtla/common_top_options.txt @@ -0,0 +1,3 @@ +**-q**, **--quiet** + + Print only a summary at the end of the session. diff --git a/Documentation/tools/rtla/index.rst b/Documentation/tools/rtla/index.rst new file mode 100644 index 000000000..7664d6d0c --- /dev/null +++ b/Documentation/tools/rtla/index.rst @@ -0,0 +1,20 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================================ +The realtime Linux analysis tool +================================ + +RTLA provides a set of tools for the analysis of the kernel's realtime +behavior on specific hardware. + +.. toctree:: + :maxdepth: 1 + + rtla + rtla-osnoise + rtla-osnoise-hist + rtla-osnoise-top + rtla-timerlat + rtla-timerlat-hist + rtla-timerlat-top + rtla-hwnoise diff --git a/Documentation/tools/rtla/rtla-hwnoise.rst b/Documentation/tools/rtla/rtla-hwnoise.rst new file mode 100644 index 000000000..5930bbca4 --- /dev/null +++ b/Documentation/tools/rtla/rtla-hwnoise.rst @@ -0,0 +1,109 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. |tool| replace:: hwnoise + +============ +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.txt + +.. include:: common_top_options.txt + +.. include:: common_options.txt + +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 <https://docs.kernel.org/trace/osnoise-tracer.html>`__ + +AUTHOR +====== +Written by Daniel Bristot de Oliveira <bristot@kernel.org> + +.. include:: common_appendix.txt diff --git a/Documentation/tools/rtla/rtla-osnoise-hist.rst b/Documentation/tools/rtla/rtla-osnoise-hist.rst new file mode 100644 index 000000000..6ddea2c6d --- /dev/null +++ b/Documentation/tools/rtla/rtla-osnoise-hist.rst @@ -0,0 +1,68 @@ +.. |tool| replace:: osnoise hist + +=================== +rtla-osnoise-hist +=================== +------------------------------------------------------ +Display a histogram of the osnoise tracer samples +------------------------------------------------------ + +:Manual section: 1 + +SYNOPSIS +======== +**rtla osnoise hist** [*OPTIONS*] + +DESCRIPTION +=========== +.. include:: common_osnoise_description.txt + +The **rtla osnoise hist** tool collects all **osnoise:sample_threshold** +occurrence in a histogram, displaying the results in a user-friendly way. +The tool also allows many configurations of the *osnoise* tracer and the +collection of the tracer output. + +OPTIONS +======= +.. include:: common_osnoise_options.txt + +.. include:: common_hist_options.txt + +.. include:: common_options.txt + +EXAMPLE +======= +In the example below, *osnoise* tracer threads are set to run with real-time +priority *FIFO:1*, on CPUs *0-11*, for *900ms* at each period (*1s* by +default). The reason for reducing the runtime is to avoid starving the +**rtla** tool. The tool is also set to run for *one minute*. The output +histogram is set to group outputs in buckets of *10us* and *25* entries:: + + [root@f34 ~/]# rtla osnoise hist -P F:1 -c 0-11 -r 900000 -d 1M -b 10 -E 25 + # RTLA osnoise histogram + # Time unit is microseconds (us) + # Duration: 0 00:01:00 + Index CPU-000 CPU-001 CPU-002 CPU-003 CPU-004 CPU-005 CPU-006 CPU-007 CPU-008 CPU-009 CPU-010 CPU-011 + 0 42982 46287 51779 53740 52024 44817 49898 36500 50408 50128 49523 52377 + 10 12224 8356 2912 878 2667 10155 4573 18894 4214 4836 5708 2413 + 20 8 5 12 2 13 24 20 41 29 53 39 39 + 30 1 1 0 0 10 3 6 19 15 31 30 38 + 40 0 0 0 0 0 4 2 7 2 3 8 11 + 50 0 0 0 0 0 0 0 0 0 1 1 2 + over: 0 0 0 0 0 0 0 0 0 0 0 0 + count: 55215 54649 54703 54620 54714 55003 54499 55461 54668 55052 55309 54880 + min: 0 0 0 0 0 0 0 0 0 0 0 0 + avg: 0 0 0 0 0 0 0 0 0 0 0 0 + max: 30 30 20 20 30 40 40 40 40 50 50 50 + +SEE ALSO +======== +**rtla-osnoise**\(1), **rtla-osnoise-top**\(1) + +`Osnoise tracer <https://docs.kernel.org/trace/osnoise-tracer.html>`__ + +AUTHOR +====== +Written by Daniel Bristot de Oliveira <bristot@kernel.org> + +.. include:: common_appendix.txt diff --git a/Documentation/tools/rtla/rtla-osnoise-top.rst b/Documentation/tools/rtla/rtla-osnoise-top.rst new file mode 100644 index 000000000..b91c02ac2 --- /dev/null +++ b/Documentation/tools/rtla/rtla-osnoise-top.rst @@ -0,0 +1,63 @@ +.. |tool| replace:: osnoise top + +=================== +rtla-osnoise-top +=================== +----------------------------------------------- +Display a summary of the operating system noise +----------------------------------------------- + +:Manual section: 1 + +SYNOPSIS +======== +**rtla osnoise top** [*OPTIONS*] + +DESCRIPTION +=========== +.. include:: common_osnoise_description.txt + +**rtla osnoise top** collects the periodic summary from the *osnoise* tracer, +including the counters of the occurrence of the interference source, +displaying the results in a user-friendly format. + +The tool also allows many configurations of the *osnoise* tracer and the +collection of the tracer output. + +OPTIONS +======= +.. include:: common_osnoise_options.txt + +.. include:: common_top_options.txt + +.. include:: common_options.txt + +EXAMPLE +======= +In the example below, the **rtla osnoise top** tool is set to run with a +real-time priority *FIFO:1*, on CPUs *0-3*, for *900ms* at each period +(*1s* by default). The reason for reducing the runtime is to avoid starving +the rtla tool. The tool is also set to run for *one minute* and to display +a summary of the report at the end of the session:: + + [root@f34 ~]# rtla osnoise top -P F:1 -c 0-3 -r 900000 -d 1M -q + Operating System Noise + duration: 0 00:01:00 | time is in us + CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI IRQ Softirq Thread + 0 #59 53100000 304896 99.42580 6978 56 549 0 53111 1590 13 + 1 #59 53100000 338339 99.36282 8092 24 399 0 53130 1448 31 + 2 #59 53100000 290842 99.45227 6582 39 855 0 53110 1406 12 + 3 #59 53100000 204935 99.61405 6251 33 290 0 53156 1460 12 + +SEE ALSO +======== + +**rtla-osnoise**\(1), **rtla-osnoise-hist**\(1) + +`Osnoise tracer <https://docs.kernel.org/trace/osnoise-tracer.html>`__ + +AUTHOR +====== +Written by Daniel Bristot de Oliveira <bristot@kernel.org> + +.. include:: common_appendix.txt diff --git a/Documentation/tools/rtla/rtla-osnoise.rst b/Documentation/tools/rtla/rtla-osnoise.rst new file mode 100644 index 000000000..decd9e11f --- /dev/null +++ b/Documentation/tools/rtla/rtla-osnoise.rst @@ -0,0 +1,59 @@ +=============== +rtla-osnoise +=============== +------------------------------------------------------------------ +Measure the operating system noise +------------------------------------------------------------------ + +:Manual section: 1 + +SYNOPSIS +======== +**rtla osnoise** [*MODE*] ... + +DESCRIPTION +=========== + +.. include:: common_osnoise_description.txt + +The *osnoise* tracer outputs information in two ways. It periodically prints +a summary of the noise of the operating system, including the counters of +the occurrence of the source of interference. It also provides information +for each noise via the **osnoise:** tracepoints. The **rtla osnoise top** +mode displays information about the periodic summary from the *osnoise* tracer. +The **rtla osnoise hist** mode displays information about the noise using +the **osnoise:** tracepoints. For further details, please refer to the +respective man page. + +MODES +===== +**top** + + Prints the summary from osnoise tracer. + +**hist** + + Prints a histogram of osnoise samples. + +If no MODE is given, the top mode is called, passing the arguments. + +OPTIONS +======= + +**-h**, **--help** + + Display the help text. + +For other options, see the man page for the corresponding mode. + +SEE ALSO +======== +**rtla-osnoise-top**\(1), **rtla-osnoise-hist**\(1) + +`Osnoise tracer <https://docs.kernel.org/trace/osnoise-tracer.html>`__ + +AUTHOR +====== +Written by Daniel Bristot de Oliveira <bristot@kernel.org> + +.. include:: common_appendix.txt diff --git a/Documentation/tools/rtla/rtla-timerlat-hist.rst b/Documentation/tools/rtla/rtla-timerlat-hist.rst new file mode 100644 index 000000000..dab75677b --- /dev/null +++ b/Documentation/tools/rtla/rtla-timerlat-hist.rst @@ -0,0 +1,113 @@ +.. |tool| replace:: timerlat hist + +===================== +rtla-timerlat-hist +===================== +------------------------------------------------ +Histograms of the operating system timer latency +------------------------------------------------ + +:Manual section: 1 + +SYNOPSIS +======== +**rtla timerlat hist** [*OPTIONS*] ... + +DESCRIPTION +=========== + +.. include:: common_timerlat_description.txt + +The **rtla timerlat hist** displays a histogram of each tracer event +occurrence. This tool uses the periodic information, and the +**osnoise:** tracepoints are enabled when using the **-T** option. + +OPTIONS +======= + +.. include:: common_timerlat_options.txt + +.. include:: common_hist_options.txt + +.. include:: common_options.txt + +.. include:: common_timerlat_aa.txt + +EXAMPLE +======= +In the example below, **rtla timerlat hist** is set to run for *10* minutes, +in the cpus *0-4*, *skipping zero* only lines. Moreover, **rtla timerlat +hist** will change the priority of the *timerlat* threads to run under +*SCHED_DEADLINE* priority, with a *100us* runtime every *1ms* period. The +*1ms* period is also passed to the *timerlat* tracer. Auto-analysis is disabled +to reduce overhead :: + + [root@alien ~]# timerlat hist -d 10m -c 0-4 -P d:100us:1ms -p 1000 --no-aa + # RTLA timerlat histogram + # Time unit is microseconds (us) + # Duration: 0 00:10:00 + Index IRQ-000 Thr-000 IRQ-001 Thr-001 IRQ-002 Thr-002 IRQ-003 Thr-003 IRQ-004 Thr-004 + 0 276489 0 206089 0 466018 0 481102 0 205546 0 + 1 318327 35487 388149 30024 94531 48382 83082 71078 388026 55730 + 2 3282 122584 4019 126527 28231 109012 23311 89309 4568 98739 + 3 940 11815 837 9863 6209 16227 6895 17196 910 9780 + 4 444 17287 424 11574 2097 38443 2169 36736 462 13476 + 5 206 43291 255 25581 1223 101908 1304 101137 236 28913 + 6 132 101501 96 64584 635 213774 757 215471 99 73453 + 7 74 169347 65 124758 350 57466 441 53639 69 148573 + 8 53 85183 31 156751 229 9052 306 9026 39 139907 + 9 22 10387 12 42762 161 2554 225 2689 19 26192 + 10 13 1898 8 5770 114 1247 128 1405 13 3772 + 11 9 560 9 924 71 686 76 765 8 713 + 12 4 256 2 360 50 411 64 474 3 278 + 13 2 167 2 172 43 256 53 350 4 180 + 14 1 88 1 116 15 198 42 223 0 115 + 15 2 63 3 94 11 139 20 150 0 58 + 16 2 37 0 56 5 78 10 102 0 39 + 17 0 18 0 28 4 57 8 80 0 15 + 18 0 8 0 17 2 50 6 56 0 12 + 19 0 9 0 5 0 19 0 48 0 18 + 20 0 4 0 8 0 11 2 27 0 4 + 21 0 2 0 3 1 9 1 18 0 6 + 22 0 1 0 3 1 7 0 3 0 5 + 23 0 2 0 4 0 2 0 7 0 2 + 24 0 2 0 2 1 3 0 3 0 5 + 25 0 0 0 1 0 1 0 1 0 3 + 26 0 1 0 0 0 2 0 2 0 0 + 27 0 0 0 3 0 1 0 0 0 1 + 28 0 0 0 3 0 0 0 1 0 0 + 29 0 0 0 2 0 2 0 1 0 3 + 30 0 1 0 0 0 0 0 0 0 0 + 31 0 1 0 0 0 0 0 2 0 2 + 32 0 0 0 1 0 2 0 0 0 0 + 33 0 0 0 2 0 0 0 0 0 1 + 34 0 0 0 0 0 0 0 0 0 2 + 35 0 1 0 1 0 0 0 0 0 1 + 36 0 1 0 0 0 1 0 1 0 0 + 37 0 0 0 1 0 0 0 0 0 0 + 40 0 0 0 0 0 1 0 1 0 0 + 41 0 0 0 0 0 0 0 0 0 1 + 42 0 0 0 0 0 0 0 0 0 1 + 44 0 0 0 0 0 1 0 0 0 0 + 46 0 0 0 0 0 0 0 1 0 0 + 47 0 0 0 0 0 0 0 0 0 1 + 50 0 0 0 0 0 0 0 0 0 1 + 54 0 0 0 1 0 0 0 0 0 0 + 58 0 0 0 1 0 0 0 0 0 0 + over: 0 0 0 0 0 0 0 0 0 0 + count: 600002 600002 600002 600002 600002 600002 600002 600002 600002 600002 + min: 0 1 0 1 0 1 0 1 0 1 + avg: 0 5 0 5 0 4 0 4 0 5 + max: 16 36 15 58 24 44 21 46 13 50 + +SEE ALSO +======== +**rtla-timerlat**\(1), **rtla-timerlat-top**\(1) + +`Timerlat tracer <https://docs.kernel.org/trace/timerlat-tracer.html>`__ + +AUTHOR +====== +Written by Daniel Bristot de Oliveira <bristot@kernel.org> + +.. include:: common_appendix.txt diff --git a/Documentation/tools/rtla/rtla-timerlat-top.rst b/Documentation/tools/rtla/rtla-timerlat-top.rst new file mode 100644 index 000000000..05959f1a4 --- /dev/null +++ b/Documentation/tools/rtla/rtla-timerlat-top.rst @@ -0,0 +1,136 @@ +.. |tool| replace:: timerlat top + +==================== +rtla-timerlat-top +==================== +------------------------------------------- +Measures the operating system timer latency +------------------------------------------- + +:Manual section: 1 + +SYNOPSIS +======== +**rtla timerlat top** [*OPTIONS*] ... + +DESCRIPTION +=========== + +.. include:: common_timerlat_description.txt + +The **rtla timerlat top** displays a summary of the periodic output +from the *timerlat* tracer. It also provides information for each +operating system noise via the **osnoise:** tracepoints that can be +seen with the option **-T**. + +OPTIONS +======= + +.. include:: common_timerlat_options.txt + +.. include:: common_top_options.txt + +.. include:: common_options.txt + +.. include:: common_timerlat_aa.txt + +**--aa-only** *us* + + Set stop tracing conditions and run without collecting and displaying statistics. + Print the auto-analysis if the system hits the stop tracing condition. This option + is useful to reduce rtla timerlat CPU, enabling the debug without the overhead of + collecting the statistics. + +EXAMPLE +======= + +In the example below, the timerlat tracer is dispatched in cpus *1-23* in the +automatic trace mode, instructing the tracer to stop if a *40 us* latency or +higher is found:: + + # timerlat -a 40 -c 1-23 -q + Timer Latency + 0 00:00:12 | IRQ Timer Latency (us) | Thread Timer Latency (us) + CPU COUNT | cur min avg max | cur min avg max + 1 #12322 | 0 0 1 15 | 10 3 9 31 + 2 #12322 | 3 0 1 12 | 10 3 9 23 + 3 #12322 | 1 0 1 21 | 8 2 8 34 + 4 #12322 | 1 0 1 17 | 10 2 11 33 + 5 #12322 | 0 0 1 12 | 8 3 8 25 + 6 #12322 | 1 0 1 14 | 16 3 11 35 + 7 #12322 | 0 0 1 14 | 9 2 8 29 + 8 #12322 | 1 0 1 22 | 9 3 9 34 + 9 #12322 | 0 0 1 14 | 8 2 8 24 + 10 #12322 | 1 0 0 12 | 9 3 8 24 + 11 #12322 | 0 0 0 15 | 6 2 7 29 + 12 #12321 | 1 0 0 13 | 5 3 8 23 + 13 #12319 | 0 0 1 14 | 9 3 9 26 + 14 #12321 | 1 0 0 13 | 6 2 8 24 + 15 #12321 | 1 0 1 15 | 12 3 11 27 + 16 #12318 | 0 0 1 13 | 7 3 10 24 + 17 #12319 | 0 0 1 13 | 11 3 9 25 + 18 #12318 | 0 0 0 12 | 8 2 8 20 + 19 #12319 | 0 0 1 18 | 10 2 9 28 + 20 #12317 | 0 0 0 20 | 9 3 8 34 + 21 #12318 | 0 0 0 13 | 8 3 8 28 + 22 #12319 | 0 0 1 11 | 8 3 10 22 + 23 #12320 | 28 0 1 28 | 41 3 11 41 + rtla timerlat hit stop tracing + ## CPU 23 hit stop tracing, analyzing it ## + IRQ handler delay: 27.49 us (65.52 %) + IRQ latency: 28.13 us + Timerlat IRQ duration: 9.59 us (22.85 %) + Blocking thread: 3.79 us (9.03 %) + objtool:49256 3.79 us + Blocking thread stacktrace + -> timerlat_irq + -> __hrtimer_run_queues + -> hrtimer_interrupt + -> __sysvec_apic_timer_interrupt + -> sysvec_apic_timer_interrupt + -> asm_sysvec_apic_timer_interrupt + -> _raw_spin_unlock_irqrestore + -> cgroup_rstat_flush_locked + -> cgroup_rstat_flush_irqsafe + -> mem_cgroup_flush_stats + -> mem_cgroup_wb_stats + -> balance_dirty_pages + -> balance_dirty_pages_ratelimited_flags + -> btrfs_buffered_write + -> btrfs_do_write_iter + -> vfs_write + -> __x64_sys_pwrite64 + -> do_syscall_64 + -> entry_SYSCALL_64_after_hwframe + ------------------------------------------------------------------------ + Thread latency: 41.96 us (100%) + + The system has exit from idle latency! + Max timerlat IRQ latency from idle: 17.48 us in cpu 4 + Saving trace to timerlat_trace.txt + +In this case, the major factor was the delay suffered by the *IRQ handler* +that handles **timerlat** wakeup: *65.52%*. This can be caused by the +current thread masking interrupts, which can be seen in the blocking +thread stacktrace: the current thread (*objtool:49256*) disabled interrupts +via *raw spin lock* operations inside mem cgroup, while doing write +syscall in a btrfs file system. + +The raw trace is saved in the **timerlat_trace.txt** file for further analysis. + +Note that **rtla timerlat** was dispatched without changing *timerlat* tracer +threads' priority. That is generally not needed because these threads have +priority *FIFO:95* by default, which is a common priority used by real-time +kernel developers to analyze scheduling delays. + +SEE ALSO +-------- +**rtla-timerlat**\(1), **rtla-timerlat-hist**\(1) + +`Timerlat tracer <https://docs.kernel.org/trace/timerlat-tracer.html>`__ + +AUTHOR +------ +Written by Daniel Bristot de Oliveira <bristot@kernel.org> + +.. include:: common_appendix.txt diff --git a/Documentation/tools/rtla/rtla-timerlat.rst b/Documentation/tools/rtla/rtla-timerlat.rst new file mode 100644 index 000000000..63718c52a --- /dev/null +++ b/Documentation/tools/rtla/rtla-timerlat.rst @@ -0,0 +1,54 @@ +================ +rtla-timerlat +================ +------------------------------------------- +Measures the operating system timer latency +------------------------------------------- + +:Manual section: 1 + +SYNOPSIS +======== +**rtla timerlat** [*MODE*] ... + +DESCRIPTION +=========== + +.. include:: common_timerlat_description.txt + +The **rtla timerlat top** mode displays a summary of the periodic output +from the *timerlat* tracer. The **rtla timerlat hist** mode displays +a histogram of each tracer event occurrence. For further details, please +refer to the respective man page. + +MODES +===== +**top** + + Prints the summary from *timerlat* tracer. + +**hist** + + Prints a histogram of timerlat samples. + +If no *MODE* is given, the top mode is called, passing the arguments. + +OPTIONS +======= +**-h**, **--help** + + Display the help text. + +For other options, see the man page for the corresponding mode. + +SEE ALSO +======== +**rtla-timerlat-top**\(1), **rtla-timerlat-hist**\(1) + +`Timerlat tracer <https://docs.kernel.org/trace/timerlat-tracer.html>`__ + +AUTHOR +====== +Written by Daniel Bristot de Oliveira <bristot@kernel.org> + +.. include:: common_appendix.txt diff --git a/Documentation/tools/rtla/rtla.rst b/Documentation/tools/rtla/rtla.rst new file mode 100644 index 000000000..6df1296b8 --- /dev/null +++ b/Documentation/tools/rtla/rtla.rst @@ -0,0 +1,52 @@ +========= +rtla +========= +-------------------------------- +Real-time Linux Analysis tool +-------------------------------- + +:Manual section: 1 + +SYNOPSIS +======== +**rtla** *COMMAND* [*OPTIONS*] + +DESCRIPTION +=========== +The **rtla** is a meta-tool that includes a set of commands that aims to +analyze the real-time properties of Linux. But instead of testing Linux +as a black box, **rtla** leverages kernel tracing capabilities to provide +precise information about the properties and root causes of unexpected +results. + +COMMANDS +======== +**hwnoise** + + Detect and quantify hardware-related noise. + +**osnoise** + + Gives information about the operating system noise (osnoise). + +**timerlat** + + Measures the IRQ and thread timer latency. + +OPTIONS +======= +**-h**, **--help** + + Display the help text. + +For other options, see the man page for the corresponding command. + +SEE ALSO +======== +**rtla-hwnoise**\(1), **rtla-osnoise**\(1), **rtla-timerlat**\(1) + +AUTHOR +====== +Daniel Bristot de Oliveira <bristot@kernel.org> + +.. include:: common_appendix.txt |