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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
| commit | cf9610f9116d55c5a66ef9f1faecacabd93a9322 (patch) | |
| tree | 757a3d280760c654767631cab5ad8af2d86d1848 /Documentation/tools/rtla/rtla-timerlat-top.rst | |
| download | linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.tar.gz linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.zip | |
Merge tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrlgrafted
Pull pin control updates from Linus Walleij:
"Core changes:
- Use the non-blocking mux_state_try_select() in the generic MUX pin
control back-end
- Free pin maps on pinctrl_generic_to_map() failure in the core
helpers
New hardware pin control:
- Qualcomm Maili TLMM SoC, PMG1110 PMIC, and Eliza LPASS LPI TLMM SoC
(this is for the low power audio, LPASS = Low Power Audio SubSystem
portions)
- Upboard support on top of the Intel pin controller
- Apple T6030 and T6031 support (just compatible strings)
- Samsung Exynos 8855 SoC
- Mediatek MT6858 SoC
- Rockchip RK3308B and RV1106 SoCs
- Airoha EN7523 and AN7563 SoCs
Improvements:
- Qualcomm TLMM GPIOs are unconditionally marked as wakeup capable
- Qualcomm improvements on top of the Qualcomm PDC (power domain
controller) irqchip improvements from tglx:s tree
- Qualcomm IPQ806x and IPQ9650 non-urgent pin grop fixups
- The NPCM8xx driver has been put into shape fixing many pin and
group definitions
- Some non-urgent Tegra 264 pin assignments are fixed up
- Some non-urgent fixups to Airoha AN7581 and AN7583 registers and
pin assignments, missing features etc"
* tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: (130 commits)
dt-bindings: pinctrl: Convert TI DA850 pupd to DT schema
pinctrl: meson: sync some modify from A4
pinctrl: meson: a4: Add input enable pin configuration
pinctrl: realtek: rtd1625: remove unused group name spdif_sel
pinctrl: realtek: rtd1625: fix base_bit for VE4 GPIO 13
dt-bindings: pinctrl: microchip,pic32mzda-pinctrl: Convert to DT schema
Revert "Merge branch 'ib-rsk7204' into devel"
pinctrl: rockchip: Add RV1106 pinctrl support
dt-bindings: pinctrl: rockchip: Add RV1106 compatible
pinctrl: rockchip: Decode drive strength in the get function
pinctrl: fix PINCTRL_GENERIC_MUX not always being selectable
pinctrl: airoha: add support of an7563 SoC
dt-bindings: pinctrl: airoha: add support of an7563 pin controller
pinctrl: airoha: try to find chip scu node by phandle first
pinctrl: airoha: add support of en7523 SoC
dt-bindings: pinctrl: airoha: add support of en7523 pin controller
pinctrl: airoha: an7583: add support for olt pinmux
pinctrl: airoha: an7583: add support for pon_alt pinmux
pinctrl: airoha: an7583: add support for npu_uart pinmux
dt-bindings: pinctrl: airoha: an7583: add missed features
...
Diffstat (limited to 'Documentation/tools/rtla/rtla-timerlat-top.rst')
| -rw-r--r-- | Documentation/tools/rtla/rtla-timerlat-top.rst | 136 |
1 files changed, 136 insertions, 0 deletions
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 |
