kernel/git/stable/linux.git/tools/perf/Documentation, branch linux-6.10.y

perf sched: Rename 'switches' column header to 'count' and add usage description, options for latency

2024-05-10T14:10:03+00:00

Rename 'Switches' to 'Count' and document metrics shown for perf sched latency output. Also add options possible with perf sched latency. Initially, after seeing the output of 'perf sched latency', the term 'Switches' seemed like it's the number of context switches-in for a particular task, but upon going through the code, it was observed that it's actually keeping track of number of times a delay was calculated so that it is used in calculation of the average delay. Actually, the switches here is a subset of number of context switches-in because there are some cases where the count is not incremented in switch-in handler 'add_sched_in_event'. For example when a task is switched-in while it's state is not ready to run(!= THREAD_WAIT_CPU). commit d9340c1db3f52460 ("perf sched: Display time in milliseconds, reorganize output") changed it from the original count to switches. So, renamed switches to count to make things a bit more clearer and added the metrics description of latency in the document. Reviewed-by: Aditya Gupta Signed-off-by: Madadi Vineeth Reddy Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240328090005.8321-1-vineethr@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo

perf test: Reintroduce -p/--parallel and make -S/--sequential the default

2024-04-27T01:28:08+00:00

We can't default to doing parallel tests as there are tests that compete for the same resources and thus clash, for instance tests that put in place 'perf probe' probes, that clean the probes without regard to other tests needs, ARM64 coresight tests, Intel PT ones, etc. So reintroduce --p/--parallel and make -S/--sequential the default. We need to come up with infrastructure that state which tests can't run in parallel because they need exclusive access to some resource, something as simple as "probes" that would then avoid 'perf probe' tests from running while other such test is running, or make the tests more resilient, till then we can't use parallel mode as default. While at it, document all these options in the 'perf test' man page. Reported-by: Adrian Hunter Reported-by: Arnaldo Carvalho de Melo Reported-by: James Clark Reviewed-by: Ian Rogers Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Link: https://lore.kernel.org/lkml/Ziwm18BqIn_vc1vn@x1 Signed-off-by: Arnaldo Carvalho de Melo

perf docs: Document bpf event modifier

2024-04-19T01:22:51+00:00

Document that 'b' is used as a modifier to make an event use a BPF counter. Fixes: 01bd8efcec444468 ("perf stat: Introduce ':b' modifier") Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Athira Rajeev Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Song Liu Cc: Thomas Richter Link: https://lore.kernel.org/r/20240416170014.985191-1-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf report: Add weight[123] output fields

2024-04-17T15:21:39+00:00

Add weight1, weight2 and weight3 fields to -F/--fields and their aliases like 'ins_lat', 'p_stage_cyc' and 'retire_lat'. Note that they are in the sort keys too but the difference is that output fields will sum up the weight values and display the average. In the sort key, users can see the distribution of weight value and I think it's confusing we have local vs. global weight for the same weight. For example, I experiment with mem-loads events to get the weights. On my laptop, it seems only weight1 field is supported. $ perf mem record -- perf test -w noploop Let's look at the noploop function only. It has 7 samples. $ perf script -F event,ip,sym,weight | grep noploop # event weight ip sym cpu/mem-loads,ldlat=30/P: 43 55b3c122bffc noploop cpu/mem-loads,ldlat=30/P: 48 55b3c122bffc noploop cpu/mem-loads,ldlat=30/P: 38 55b3c122bffc noploop <--- same weight cpu/mem-loads,ldlat=30/P: 38 55b3c122bffc noploop <--- same weight cpu/mem-loads,ldlat=30/P: 59 55b3c122bffc noploop cpu/mem-loads,ldlat=30/P: 33 55b3c122bffc noploop cpu/mem-loads,ldlat=30/P: 38 55b3c122bffc noploop <--- same weight When you use the 'weight' sort key, it'd show entries with a separate weight value separately. Also note that the first entry has 3 samples with weight value 38, so they are displayed together and the weight value is the sum of 3 samples (114 = 38 * 3). $ perf report -n -s +weight | grep -e Weight -e noploop # Overhead Samples Command Shared Object Symbol Weight 0.53% 3 perf perf [.] noploop 114 0.18% 1 perf perf [.] noploop 59 0.18% 1 perf perf [.] noploop 48 0.18% 1 perf perf [.] noploop 43 0.18% 1 perf perf [.] noploop 33 If you use 'local_weight' sort key, you can see the actual weight. $ perf report -n -s +local_weight | grep -e Weight -e noploop # Overhead Samples Command Shared Object Symbol Local Weight 0.53% 3 perf perf [.] noploop 38 0.18% 1 perf perf [.] noploop 59 0.18% 1 perf perf [.] noploop 48 0.18% 1 perf perf [.] noploop 43 0.18% 1 perf perf [.] noploop 33 But when you use the -F/--field option instead, you can see the average weight for the while noploop function (as it won't group samples by weight value and use the default 'comm,dso,sym' sort keys). $ perf report -n -F +weight | grep -e Weight -e noploop Warning: --fields weight shows the average value unlike in the --sort key. # Overhead Samples Weight1 Command Shared Object Symbol 1.23% 7 42.4 perf perf [.] noploop The weight1 field shows the average value: (38 * 3 + 59 + 48 + 43 + 33) / 7 = 42.4 Also it'd show the warning that 'weight' field has the average value. Using 'weight1' can remove the warning. Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: Andi Kleen Cc: Athira Rajeev Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Peter Zijlstra Cc: Stephane Eranian Link: https://lore.kernel.org/r/20240411181718.2367948-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf script: Add capstone support for '-F +brstackdisasm'

2024-04-05T13:43:07+00:00

Support capstone output for the '-F +brstackinsn' branch dump. The new output is enabled with the new field 'brstackdisasm'. This was possible before with --xed, but now also allow it for users that don't have xed using the builtin capstone support. Before: perf record -b emacs -Q --batch '()' perf script -F +brstackinsn ... emacs 55778 1814366.755945: 151564 cycles:P: 7f0ab2d17192 intel_check_word.constprop.0+0x162 (/usr/lib64/ld-linux-x86-64.s> intel_check_word.constprop.0+237: 00007f0ab2d1711d insn: 75 e6 # PRED 3 cycles [3] 00007f0ab2d17105 insn: 73 51 00007f0ab2d17107 insn: 48 89 c1 00007f0ab2d1710a insn: 48 39 ca 00007f0ab2d1710d insn: 73 96 00007f0ab2d1710f insn: 48 8d 04 11 00007f0ab2d17113 insn: 48 d1 e8 00007f0ab2d17116 insn: 49 8d 34 c1 00007f0ab2d1711a insn: 44 3a 06 00007f0ab2d1711d insn: 75 e6 # PRED 3 cycles [6] 3.00 IPC 00007f0ab2d17105 insn: 73 51 # PRED 1 cycles [7] 1.00 IPC 00007f0ab2d17158 insn: 48 8d 50 01 00007f0ab2d1715c insn: eb 92 # PRED 1 cycles [8] 2.00 IPC 00007f0ab2d170f0 insn: 48 39 ca 00007f0ab2d170f3 insn: 73 b0 # PRED 1 cycles [9] 2.00 IPC After (perf must be compiled with capstone): perf script -F +brstackdisasm ... emacs 55778 1814366.755945: 151564 cycles:P: 7f0ab2d17192 intel_check_word.constprop.0+0x162 (/usr/lib64/ld-linux-x86-64.s> intel_check_word.constprop.0+237: 00007f0ab2d1711d jne intel_check_word.constprop.0+0xd5 # PRED 3 cycles [3] 00007f0ab2d17105 jae intel_check_word.constprop.0+0x128 00007f0ab2d17107 movq %rax, %rcx 00007f0ab2d1710a cmpq %rcx, %rdx 00007f0ab2d1710d jae intel_check_word.constprop.0+0x75 00007f0ab2d1710f leaq (%rcx, %rdx), %rax 00007f0ab2d17113 shrq $1, %rax 00007f0ab2d17116 leaq (%r9, %rax, 8), %rsi 00007f0ab2d1711a cmpb (%rsi), %r8b 00007f0ab2d1711d jne intel_check_word.constprop.0+0xd5 # PRED 3 cycles [6] 3.00 IPC 00007f0ab2d17105 jae intel_check_word.constprop.0+0x128 # PRED 1 cycles [7] 1.00 IPC 00007f0ab2d17158 leaq 1(%rax), %rdx 00007f0ab2d1715c jmp intel_check_word.constprop.0+0xc0 # PRED 1 cycles [8] 2.00 IPC 00007f0ab2d170f0 cmpq %rcx, %rdx 00007f0ab2d170f3 jae intel_check_word.constprop.0+0x75 # PRED 1 cycles [9] 2.00 IPC Reviewed-by: Adrian Hunter Signed-off-by: Andi Kleen Link: https://lore.kernel.org/r/20240401210925.209671-3-ak@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf docs arm_spe: Clarify more SPE requirements related to KPTI

2024-03-21T13:41:27+00:00

The question of exactly when KPTI needs to be disabled comes up a lot because it doesn't always need to be done. Add the relevant kernel function and some examples that describe the behavior. Also describe the interrupt requirement and that no error message will be printed if this isn't met. Reviewed-by: Ian Rogers Signed-off-by: James Clark Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ingo Molnar Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240312132508.423320-1-james.clark@arm.com Signed-off-by: Arnaldo Carvalho de Melo

perf: script: prefer capstone to XED

2024-02-21T02:07:34+00:00

Now perf can show assembly instructions with libcapstone for x86, and the capstone is better in general. Signed-off-by: Changbin Du Reviewed-by: Adrian Hunter Cc: changbin.du@gmail.com Cc: Thomas Richter Cc: Andi Kleen Signed-off-by: Namhyung Kim Link: https://lore.kernel.org/r/20240217074046.4100789-6-changbin.du@huawei.com

perf: script: add raw|disasm arguments to --insn-trace option

2024-02-21T02:07:21+00:00

Now '--insn-trace' accept a argument to specify the output format: - raw: display raw instructions. - disasm: display mnemonic instructions (if capstone is installed). $ sudo perf script --insn-trace=raw ls 1443864 [006] 2275506.209908875: 7f216b426100 _start+0x0 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) insn: 48 89 e7 ls 1443864 [006] 2275506.209908875: 7f216b426103 _start+0x3 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) insn: e8 e8 0c 00 00 ls 1443864 [006] 2275506.209908875: 7f216b426df0 _dl_start+0x0 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) insn: f3 0f 1e fa $ sudo perf script --insn-trace=disasm ls 1443864 [006] 2275506.209908875: 7f216b426100 _start+0x0 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) movq %rsp, %rdi ls 1443864 [006] 2275506.209908875: 7f216b426103 _start+0x3 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) callq _dl_start+0x0 ls 1443864 [006] 2275506.209908875: 7f216b426df0 _dl_start+0x0 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) illegal instruction ls 1443864 [006] 2275506.209908875: 7f216b426df4 _dl_start+0x4 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) pushq %rbp ls 1443864 [006] 2275506.209908875: 7f216b426df5 _dl_start+0x5 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) movq %rsp, %rbp ls 1443864 [006] 2275506.209908875: 7f216b426df8 _dl_start+0x8 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) pushq %r15 Signed-off-by: Changbin Du Reviewed-by: Adrian Hunter Cc: changbin.du@gmail.com Cc: Thomas Richter Cc: Andi Kleen Signed-off-by: Namhyung Kim Link: https://lore.kernel.org/r/20240217074046.4100789-5-changbin.du@huawei.com

perf: script: add field 'disasm' to display mnemonic instructions

2024-02-21T02:07:07+00:00

In addition to the 'insn' field, this adds a new field 'disasm' to display mnemonic instructions instead of the raw code. $ sudo perf script -F +disasm perf-exec 1443864 [006] 2275506.209848: psb: psb offs: 0 0 [unknown] ([unknown]) perf-exec 1443864 [006] 2275506.209848: cbr: cbr: 41 freq: 4100 MHz (114%) 0 [unknown] ([unknown]) ls 1443864 [006] 2275506.209905: 1 branches:uH: 7f216b426100 _start+0x0 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) movq %rsp, %rdi ls 1443864 [006] 2275506.209908: 1 branches:uH: 7f216b426103 _start+0x3 (/usr/lib/x86_64-linux-gnu/ld-2.31.so) callq _dl_start+0x0 Signed-off-by: Changbin Du Reviewed-by: Adrian Hunter Cc: changbin.du@gmail.com Cc: Thomas Richter Cc: Andi Kleen Signed-off-by: Namhyung Kim Link: https://lore.kernel.org/r/20240217074046.4100789-4-changbin.du@huawei.com

Merge branch 'perf-tools' into perf-tools-next

2024-02-12T20:19:21+00:00

To get some fixes in the perf test and JSON metrics into the development branch. Signed-off-by: Namhyung Kim