kernel/linux.git/tools/perf/Documentation, branch v6.13.2

perf disasm: Allow configuring what disassemblers to use

2024-11-13T19:27:35+00:00

The perf tools annotation code used for a long time parsing the output of binutils's objdump (or its reimplementations, like llvm's) to then parse and augment it with samples, allow navigation, etc. More recently disassemblers from the capstone and llvm (libraries, not parsing the output of tools using those libraries to mimic binutils's objdump output) were introduced. So when all those methods are available, there is a static preference for a series of attempts of disassembling a binary, with the 'llvm, capstone, objdump' sequence being hard coded. This patch allows users to change that sequence, specifying via a 'perf config' 'annotate.disassemblers' entry which and in what order disassemblers should be attempted. As alluded to in the comments in the source code of this series, this flexibility is useful for users and developers alike, elliminating the requirement to rebuild the tool with some specific set of libraries to see how the output of disassembling would be for one of these methods. root@x1:~# rm -f ~/.perfconfig root@x1:~# perf annotate -v --stdio2 update_load_avg symbol__disassemble: filename=/usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux, sym=update_load_avg, start=0xffffffffb6148fe0, en> annotating [0x6ff7170] /usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux : [0x7407ca0] update_load_avg Disassembled with llvm annotate.disassemblers=llvm,capstone,objdump Samples: 66 of event 'cpu_atom/cycles/P', 10000 Hz, Event count (approx.): 5185444, [percent: local period] update_load_avg() /usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux Percent 0xffffffff81148fe0 : 1.61 pushq %r15 pushq %r14 1.00 pushq %r13 movl %edx,%r13d 1.90 pushq %r12 pushq %rbp movq %rsi,%rbp pushq %rbx movq %rdi,%rbx subq $0x18,%rsp 15.14 movl 0x1a4(%rdi),%eax root@x1:~# perf config annotate.disassemblers=capstone root@x1:~# cat ~/.perfconfig # this file is auto-generated. [annotate] disassemblers = capstone root@x1:~# root@x1:~# perf annotate -v --stdio2 update_load_avg Disassembled with capstone annotate.disassemblers=capstone Samples: 66 of event 'cpu_atom/cycles/P', 10000 Hz, Event count (approx.): 5185444, [percent: local period] update_load_avg() /usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux Percent 0xffffffff81148fe0 : 1.61 pushq %r15 pushq %r14 1.00 pushq %r13 movl %edx,%r13d 1.90 pushq %r12 pushq %rbp movq %rsi,%rbp pushq %rbx movq %rdi,%rbx subq $0x18,%rsp 15.14 movl 0x1a4(%rdi),%eax root@x1:~# perf config annotate.disassemblers=objdump,capstone root@x1:~# perf config annotate.disassemblers annotate.disassemblers=objdump,capstone root@x1:~# cat ~/.perfconfig # this file is auto-generated. [annotate] disassemblers = objdump,capstone root@x1:~# perf annotate -v --stdio2 update_load_avg Executing: objdump --start-address=0xffffffff81148fe0 \ --stop-address=0xffffffff811497aa \ -d --no-show-raw-insn -S -C "$1" Disassembled with objdump annotate.disassemblers=objdump,capstone Samples: 66 of event 'cpu_atom/cycles/P', 10000 Hz, Event count (approx.): 5185444, [percent: local period] update_load_avg() /usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux Percent Disassembly of section .text: ffffffff81148fe0 : #define DO_ATTACH 0x4 ffffffff81148fe0 : #define DO_ATTACH 0x4 #define DO_DETACH 0x8 /* Update task and its cfs_rq load average */ static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) { 1.61 push %r15 push %r14 1.00 push %r13 mov %edx,%r13d 1.90 push %r12 push %rbp mov %rsi,%rbp push %rbx mov %rdi,%rbx sub $0x18,%rsp } /* rq->task_clock normalized against any time this cfs_rq has spent throttled */ static inline u64 cfs_rq_clock_pelt(struct cfs_rq *cfs_rq) { if (unlikely(cfs_rq->throttle_count)) 15.14 mov 0x1a4(%rdi),%eax root@x1:~# After adding a way to select the disassembler from the command line a 'perf test' comparing the output of the various diassemblers should be introduced, to test these codebases. Acked-by: Ian Rogers Cc: Adrian Hunter Cc: Athira Rajeev Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Cc: Steinar H. Gunderson Link: https://lore.kernel.org/r/20241111151734.1018476-4-acme@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf docs: Document tool and hwmon events

2024-11-09T16:28:03+00:00

Add a few paragraphs on tool and hwmon events. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Ravi Bangoria Cc: Yoshihiro Furudera Cc: Howard Chu Cc: Ze Gao Cc: Changbin Du Cc: Junhao He Cc: Weilin Wang Cc: James Clark Cc: Oliver Upton Cc: Athira Jajeev Link: https://lore.kernel.org/r/20241109003759.473460-8-irogers@google.com Signed-off-by: Namhyung Kim

perf arm-spe: Update --itrace help text

2024-10-29T23:10:17+00:00

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 test: Document the -w/--workload option

2024-10-22T04:10:50+00:00

Wasn't documented so far, mention that it is mostly used in the shell regression tests. Signed-off-by: Arnaldo Carvalho de Melo Reviewed-by: James Clark Cc: Thomas Gleixner Cc: Clark Williams Link: https://lore.kernel.org/r/20241020021842.1752770-4-acme@kernel.org Signed-off-by: Namhyung Kim

perf build: Rename HAVE_DWARF_SUPPORT to HAVE_LIBDW_SUPPORT

2024-10-18T17:17:40+00:00

In Makefile.config for unwinding the name dwarf implies either libunwind or libdw. Make it clearer that HAVE_DWARF_SUPPORT is really just defined when libdw is present by renaming to HAVE_LIBDW_SUPPORT. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Tested-by: Leo Yan Cc: Anup Patel Cc: Yang Jihong Cc: Palmer Dabbelt Cc: David S. Miller Cc: Albert Ou Cc: Shenlin Liang Cc: Nick Terrell Cc: Guilherme Amadio Cc: Steinar H. Gunderson Cc: Changbin Du Cc: Alexander Lobakin Cc: Przemek Kitszel Cc: Huacai Chen Cc: Guo Ren Cc: Masahiro Yamada Cc: Masami Hiramatsu (Google) Cc: Will Deacon Cc: James Clark Cc: Mike Leach Cc: Chen Pei Cc: Leo Yan Cc: Oliver Upton Cc: Aditya Gupta Cc: Kajol Jain Cc: Athira Rajeev Cc: linux-arm-kernel@lists.infradead.org Cc: linux-riscv@lists.infradead.org Cc: Bibo Mao Cc: John Garry Cc: Atish Patra Cc: Dima Kogan Cc: Paul Walmsley Cc: Dr. David Alan Gilbert Cc: linux-csky@vger.kernel.org Link: https://lore.kernel.org/r/20241017001354.56973-11-irogers@google.com Signed-off-by: Namhyung Kim

perf libdw: Remove unnecessary defines

2024-10-18T17:17:40+00:00

As HAVE_DWARF_GETLOCATIONS_SUPPORT and HAVE_DWARF_CFI_SUPPORT always match HAVE_DWARF_SUPPORT remove the macros and use HAVE_DWARF_SUPPORT. If building the file is guarded by CONFIG_DWARF then remove all ifs. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Anup Patel Cc: Yang Jihong Cc: Palmer Dabbelt Cc: David S. Miller Cc: Albert Ou Cc: Shenlin Liang Cc: Nick Terrell Cc: Guilherme Amadio Cc: Steinar H. Gunderson Cc: Changbin Du Cc: Alexander Lobakin Cc: Przemek Kitszel Cc: Huacai Chen Cc: Guo Ren Cc: Masahiro Yamada Cc: Masami Hiramatsu (Google) Cc: Will Deacon Cc: James Clark Cc: Mike Leach Cc: Chen Pei Cc: Leo Yan Cc: Oliver Upton Cc: Aditya Gupta Cc: Kajol Jain Cc: Athira Rajeev Cc: linux-arm-kernel@lists.infradead.org Cc: linux-riscv@lists.infradead.org Cc: Bibo Mao Cc: John Garry Cc: Atish Patra Cc: Dima Kogan Cc: Paul Walmsley Cc: Dr. David Alan Gilbert Cc: linux-csky@vger.kernel.org Link: https://lore.kernel.org/r/20241017001354.56973-10-irogers@google.com Signed-off-by: Namhyung Kim

perf sched timehist: Add pre-migration wait time option

2024-10-14T19:04:31+00:00

pre-migration wait time is the time that a task unnecessarily spends on the runqueue of a CPU but doesn't get switched-in there. In terms of tracepoints, it is the time between sched:sched_wakeup and sched:sched_migrate_task. Let's say a task woke up on CPU2, then it got migrated to CPU4 and then it's switched-in to CPU4. So, here pre-migration wait time is time that it was waiting on runqueue of CPU2 after it is woken up. The general pattern for pre-migration to occur is: sched:sched_wakeup sched:sched_migrate_task sched:sched_switch The sched:sched_waking event is used to capture the wakeup time, as it aligns with the existing code and only introduces a negligible time difference. pre-migrations are generally not useful and it increases migrations. This metric would be helpful in testing patches mainly related to wakeup and load-balancer code paths as better wakeup logic would choose an optimal CPU where task would be switched-in and thereby reducing pre- migrations. The sample output(s) when -P or --pre-migrations is used: ================= time cpu task name wait time sch delay run time pre-mig time [tid/pid] (msec) (msec) (msec) (msec) --------------- ------ ------------------------------ --------- --------- --------- --------- 38456.720806 [0001] schbench[28634/28574] 4.917 4.768 1.004 0.000 38456.720810 [0001] rcu_preempt[18] 3.919 0.003 0.004 0.000 38456.721800 [0006] schbench[28779/28574] 23.465 23.465 1.999 0.000 38456.722800 [0002] schbench[28773/28574] 60.371 60.237 3.955 60.197 38456.722806 [0001] schbench[28634/28574] 0.004 0.004 1.996 0.000 38456.722811 [0001] rcu_preempt[18] 1.996 0.005 0.005 0.000 38456.723800 [0000] schbench[28833/28574] 4.000 4.000 3.999 0.000 38456.723800 [0004] schbench[28762/28574] 42.951 42.839 3.999 39.867 38456.723802 [0007] schbench[28812/28574] 43.947 43.817 3.999 40.866 38456.723804 [0001] schbench[28587/28574] 7.935 7.822 0.993 0.000 Signed-off-by: Madadi Vineeth Reddy Reviewed-by: Tim Chen Link: https://lore.kernel.org/r/20241004170756.18064-1-vineethr@linux.ibm.com Signed-off-by: Namhyung Kim

perf report: Display columns Predicted/Abort/Cycles in --branch-history

2024-10-11T06:41:23+00:00

The original commit message: " Use current sort mechanism but the real .se_cmp() just returns 0 so that new columns "Predicted", "Abort" and "Cycles" are created in display but actually these keys are not the sort keys. For example: Overhead Source:Line Symbol Shared Object Predicted Abort Cycles ........ ............ ........ ............. ......... ..... ...... 38.25% div.c:45 [.] main div 97.6% 0 3 " Update missed commit from series "perf report: Show branch flags/cycles in --branch-history callgraph view" to apply to current repository so that new columns described above are visible. Link to original series: https://lore.kernel.org/lkml/1477876794-30749-1-git-send-email-yao.jin@linux.intel.com/ Reported-by: Dr. David Alan Gilbert Suggested-by: Kan Liang Co-developed-by: Jin Yao Signed-off-by: Jin Yao Tested-by: Thomas Falcon Signed-off-by: Thomas Falcon Link: https://lore.kernel.org/r/20241010184046.203822-1-thomas.falcon@intel.com Signed-off-by: Namhyung Kim

perf list: update option desc in man page

2024-10-03T17:01:01+00:00

There is a difference between the SYNOPSIS section of the help message and the man page (tools/perf/Documentation/perf-list.txt) for the perf list command. After checking, we found that the help message reflected the latest specifications. Therefore, revised the SYNOPSIS section of the man page to match the help message. Signed-off-by: Yoshihiro Furudera Cc: Ravi Bangoria Cc: Weilin Wang Cc: Liang Link: https://lore.kernel.org/r/20241003002404.2592094-1-fj5100bi@fujitsu.com Signed-off-by: Namhyung Kim

perf scripting python: Add function to get a config value

2024-09-24T18:47:03+00:00

This can be used to get config values like which objdump Perf uses for disassembly. Reviewed-by: Leo Yan Signed-off-by: James Clark Tested-by: Ganapatrao Kulkarni Cc: Ben Gainey Cc: Suzuki K Poulose Cc: Will Deacon Cc: Mathieu Poirier Cc: Mike Leach Cc: Ruidong Tian Cc: Leo Yan Cc: Benjamin Gray Cc: linux-arm-kernel@lists.infradead.org Cc: coresight@lists.linaro.org Cc: John Garry Cc: scclevenger@os.amperecomputing.com Link: https://lore.kernel.org/r/20240916135743.1490403-4-james.clark@linaro.org Signed-off-by: Namhyung Kim