kernel.git/tools/perf/Documentation/itrace.txt, branch master

perf arm-spe: Update --itrace help text

2024-10-29T23:10:17Z

The --itrace help now needs updating to reflect that the --itrace=b argument sythesises branches as well as branch misses. Signed-off-by: Graham Woodward Reviewed-by: James Clark Tested-by: Leo Yan Cc: nd@arm.com Cc: mike.leach@linaro.org Cc: linux-arm-kernel@lists.infradead.org Link: https://lore.kernel.org/r/20241025143009.25419-5-graham.woodward@arm.com Signed-off-by: Namhyung Kim

perf auxtrace: Add 'T' itrace option for timestamp trace

2023-11-27T13:21:27Z

An AUX trace can contain timestamp, but in some situations, the hardware trace module (e.g. Arm CoreSight) cannot decide the traced timestamp is the same source with CPU's time, thus the decoder can not use the timestamp trace for samples. This patch introduces 'T' itrace option. If users know the platforms they are working on have the same time counter with CPUs, users can use this new option to tell a decoder for using timestamp trace as kernel time. Signed-off-by: Leo Yan Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ian Rogers Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Mark Rutland Cc: Mike Leach Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Suzuki Poulouse Cc: Will Deacon Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Link: https://lore.kernel.org/r/20231014074513.1668000-2-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Synthesize cycle events

2023-02-17T14:02:44Z

There is no good reason why we cannot synthesize "cycle" events from Intel PT just as we can synthesize "instruction" events, in particular when CYC packets are available. This enables using PT to getting much more accurate cycle profiles than regular sampling (record -e cycles) when the work last for very short periods (<10 ms). Thus, add support for this, based off of the existing IPC calculation framework. The new option to --itrace is "y" (for cYcles), as c was taken for calls. Cycle and instruction events can be synthesized together, and are by default. The only real caveat is that CYC packets are only emitted whenever some other packet is, which in practice is when a branch instruction is encountered (and not even all branches). Thus, even at no subsampling (e.g. --itrace=y0ns), it is impossible to get more accuracy than a single basic block, and all cycles spent executing that block will get attributed to the branch instruction that ends the packet. Thus, one cannot know whether the cycles came from e.g. a specific load, a mispredicted branch, or something else. When subsampling (which is the default), the cycle events will get smeared out even more, but will still be generally useful to attribute cycle counts to functions. Reviewed-by: Adrian Hunter Signed-off-by: Steinar H. Gunderson Cc: Alexander Shishkin Cc: Ingo Molnar Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20220322082452.1429091-1-sesse@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf auxtrace: Add itrace option flag d+e to log on error

2022-10-04T11:55:21Z

Add flag +e to the itrace d (decoder debug log) option to get output only on decoding errors. The log can be very big so reducing the output to where there are decoding errors can be useful for analyzing errors. By default, the log size in that case is 16384 bytes, but can be altered by perf config e.g. perf config itrace.debug-log-buffer-size=30000 Reviewed-by: Andi Kleen Reviewed-by: Namhyung Kim Signed-off-by: Adrian Hunter Cc: Ian Rogers Cc: Jiri Olsa Link: https://lore.kernel.org/r/20220905073424.3971-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf auxtrace: Add itrace option "I"

2022-02-15T20:10:30Z

Add itrace option "I" to synthesize interrupt or similar (asynchronous) events. This will be used for Intel PT Event Trace events. Signed-off-by: Adrian Hunter Cc: Alexander Shishkin Cc: Andi Kleen Cc: Jiri Olsa Link: https://lore.kernel.org/r/20220124084201.2699795-13-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf auxtrace: Add itrace d+o option to direct debug log to stdout

2021-10-27T19:20:45Z

It can be useful to see debug output in between normal output. Add 'o' to the flags of debug option 'd', so that '--itrace=d+o' can specify output of the debug log to stdout. Reviewed-by: Andi Kleen Signed-off-by: Adrian Hunter Cc: Jiri Olsa Link: https://lore.kernel.org/r/20211027080334.365596-6-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf auxtrace: Add itrace A option to approximate IPC

2021-10-27T19:20:08Z

Add an option to specify that synthesized IPC can be approximate, rather than completely accurate. Reviewed-by: Andi Kleen Signed-off-by: Adrian Hunter Cc: Jiri Olsa Link: https://lore.kernel.org/r/20211027080334.365596-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf auxtrace: Add Z itrace option for timeless decoding

2021-05-12T15:43:10Z

Issues correlating timestamps can be avoided with timeless decoding. Add an option for that, so that timeless decoding can be used even when timestamps are present. Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210430070309.17624-2-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Add PSB events

2021-02-18T19:04:10Z

Emitting a PSB+ can cause a CPU a slight delay. When doing timing analysis of code with Intel PT, it is useful to know if a timing bubble was caused by Intel PT or not. Add reporting of PSB events via perf script. PSB events are printed with the existing itrace 'p' option which also prints power and frequency changes. The PSB event contains the trace offset at which the PSB occurs, to allow easy reference back to the PSB+ packets. The PSB event timestamp is always the timestamp from the PSB+ TSC packet, and the ip is always the address from the PSB+ FUP packet. The code changes are non-trivial because the decoder must walk to the PSB+ FUP address before outputting the PSB event. Example: $ perf record -e intel_pt/cyc,psb_period=0/u uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.046 MB perf.data ] $ perf script --itrace=p --ns perf 17981 [006] 25617.510820383: psb: psb offs: 0 0 [unknown] ([unknown]) perf 17981 [006] 25617.510820383: cbr: cbr: 42 freq: 4219 MHz (156%) 0 [unknown] ([unknown]) uname 17981 [006] 25617.510889753: psb: psb offs: 0xb50 7f78c12a212e __GI___tunables_init+0xee (/usr/lib/x86_64-linux-gnu/ld-2.31.so) uname 17981 [006] 25617.510899162: psb: psb offs: 0x12d0 7f78c128af1c dl_main+0x93c (/usr/lib/x86_64-linux-gnu/ld-2.31.so) uname 17981 [006] 25617.510939242: psb: psb offs: 0x1a50 7f78c128eefc _dl_map_object_from_fd+0x13c (/usr/lib/x86_64-linux-gnu/ld-2.31.so) uname 17981 [006] 25617.510981274: psb: psb offs: 0x21c8 7f78c1296307 _dl_relocate_object+0x927 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) uname 17981 [006] 25617.510993034: psb: psb offs: 0x2948 7f78c12940e4 _dl_lookup_symbol_x+0x14 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) uname 17981 [006] 25617.511003871: psb: psb offs: 0x30c8 7f78c12937b3 do_lookup_x+0x2f3 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) uname 17981 [006] 25617.511019854: psb: psb offs: 0x3850 7f78c1295eed _dl_relocate_object+0x50d (/usr/lib/x86_64-linux-gnu/ld-2.31.so) uname 17981 [006] 25617.511029015: psb: psb offs: 0x4390 7f78c12a855a strcmp+0xf6a (/usr/lib/x86_64-linux-gnu/ld-2.31.so) uname 17981 [006] 25617.511064876: psb: psb offs: 0x4b10 0 [unknown] ([unknown]) uname 17981 [006] 25617.511080762: psb: psb offs: 0x5290 7f78c11db53d _dl_addr+0x13d (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511086035: psb: psb offs: 0x5a08 7f78c11db538 _dl_addr+0x138 (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511091381: psb: psb offs: 0x6190 7f78c11db534 _dl_addr+0x134 (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511096681: psb: psb offs: 0x6910 7f78c11db4c3 _dl_addr+0xc3 (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511119520: psb: psb offs: 0x7090 7f78c10ada5e _nl_intern_locale_data+0x12e (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511126584: psb: psb offs: 0x7818 7f78c10ada50 _nl_intern_locale_data+0x120 (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511132775: psb: psb offs: 0x8358 7f78c10c20c0 getenv+0xa0 (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511134598: psb: psb offs: 0x8ad0 7f78c10ada09 _nl_intern_locale_data+0xd9 (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511135685: psb: psb offs: 0x9258 7f78c10ada50 _nl_intern_locale_data+0x120 (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511138322: psb: psb offs: 0x99d0 7f78c11fffd9 __strncmp_avx2+0x39 (/usr/lib/x86_64-linux-gnu/libc-2.31.so) uname 17981 [006] 25617.511158907: psb: psb offs: 0xa150 0 [unknown] ([unknown]) Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210205175350.23817-5-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf auxtrace: Add itrace option '-M' for memory events

2020-11-11T15:24:51Z

This patch is to add itrace option '-M' to synthesize memory event. Signed-off-by: Leo Yan Acked-by: Jiri Olsa Link: https://lore.kernel.org/r/20201106094853.21082-7-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo