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| author | Miguel Ojeda <ojeda@kernel.org> | 2026-08-16 15:32:33 +0200 |
|---|---|---|
| committer | Miguel Ojeda <ojeda@kernel.org> | 2026-08-23 21:27:17 +0200 |
| commit | 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 (patch) | |
| tree | 93a1ed1d337bc53adf1e572c2586d347703b286e /Documentation/tools/rtla/rtla-timerlat-hist.rst | |
| download | linux-stable-5febf432df1cfa5b25d99b54c32103fafbdd0eb9.tar.gz linux-stable-5febf432df1cfa5b25d99b54c32103fafbdd0eb9.zip | |
kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted
Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:
vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd
The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.
This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.
Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.
Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'Documentation/tools/rtla/rtla-timerlat-hist.rst')
| -rw-r--r-- | Documentation/tools/rtla/rtla-timerlat-hist.rst | 113 |
1 files changed, 113 insertions, 0 deletions
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 |