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2023-12-20perf maps: Add maps__load_first()Ian Rogers1-1/+1
Avoid bpf_lock_contention_read touching the internal maps data structure by adding a helper function. As access is done directly on the map in maps, hold the read lock to stop it being removed. Signed-off-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com> Cc: Changbin Du <changbin.du@huawei.com> Cc: Colin Ian King <colin.i.king@gmail.com> Cc: Dmitrii Dolgov <9erthalion6@gmail.com> Cc: German Gomez <german.gomez@arm.com> Cc: Guilherme Amadio <amadio@gentoo.org> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Clark <james.clark@arm.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: K Prateek Nayak <kprateek.nayak@amd.com> Cc: Kajol Jain <kjain@linux.ibm.com> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Leo Yan <leo.yan@linaro.org> Cc: Li Dong <lidong@vivo.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Ming Wang <wangming01@loongson.cn> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Nick Terrell <terrelln@fb.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Cc: Sandipan Das <sandipan.das@amd.com> Cc: Sean Christopherson <seanjc@google.com> Cc: Steinar H. Gunderson <sesse@google.com> Cc: Vincent Whitchurch <vincent.whitchurch@axis.com> Cc: Wenyu Liu <liuwenyu7@huawei.com> Cc: Yang Jihong <yangjihong1@huawei.com> Link: https://lore.kernel.org/r/20231207011722.1220634-20-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-11-21perf lock contention: Fix a build error on 32-bitYang Jihong1-1/+2
Fix a build error on 32-bit system: util/bpf_lock_contention.c: In function 'lock_contention_get_name': util/bpf_lock_contention.c:253:50: error: format '%lu' expects argument of type 'long unsigned int', but argument 4 has type 'u64 {aka long long unsigned int}' [-Werror=format=] snprintf(name_buf, sizeof(name_buf), "cgroup:%lu", cgrp_id); ~~^ %llu cc1: all warnings being treated as errors Fixes: d0c502e46e97 ("perf lock contention: Prepare to handle cgroups") Signed-off-by: Yang Jihong <yangjihong1@huawei.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: avagin@google.com Cc: daniel.diaz@linaro.org Link: https://lore.kernel.org/r/20231118024858.1567039-3-yangjihong1@huawei.com Signed-off-by: Namhyung Kim <namhyung@kernel.org>
2023-09-12perf lock contention: Add -G/--cgroup-filter optionNamhyung Kim1-1/+14
The -G/--cgroup-filter is to limit lock contention collection on the tasks in the specific cgroups only. $ sudo ./perf lock con -abt -G /user.slice/.../vte-spawn-52221fb8-b33f-4a52-b5c3-e35d1e6fc0e0.scope \ ./perf bench sched messaging # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 10 groups == 400 processes run Total time: 0.174 [sec] contended total wait max wait avg wait pid comm 4 114.45 us 60.06 us 28.61 us 214847 sched-messaging 2 111.40 us 60.84 us 55.70 us 214848 sched-messaging 2 106.09 us 59.42 us 53.04 us 214837 sched-messaging 1 81.70 us 81.70 us 81.70 us 214709 sched-messaging 68 78.44 us 6.83 us 1.15 us 214633 sched-messaging 69 73.71 us 2.69 us 1.07 us 214632 sched-messaging 4 72.62 us 60.83 us 18.15 us 214850 sched-messaging 2 71.75 us 67.60 us 35.88 us 214840 sched-messaging 2 69.29 us 67.53 us 34.65 us 214804 sched-messaging 2 69.00 us 68.23 us 34.50 us 214826 sched-messaging ... Export cgroup__new() function as it's needed from outside. Reviewed-by: Ian Rogers <irogers@google.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230906174903.346486-5-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-09-12perf lock contention: Add --lock-cgroup optionNamhyung Kim1-6/+10
The --lock-cgroup option shows lock contention stats break down by cgroups. Add LOCK_AGGR_CGROUP mode and use it instead of use_cgroup field. $ sudo ./perf lock con -ab --lock-cgroup sleep 1 contended total wait max wait avg wait cgroup 8 15.70 us 6.34 us 1.96 us / 2 1.48 us 747 ns 738 ns /user.slice/.../app.slice/app-gnome-google\x2dchrome-6442.scope 1 848 ns 848 ns 848 ns /user.slice/.../session.slice/org.gnome.Shell@x11.service 1 220 ns 220 ns 220 ns /user.slice/.../session.slice/pipewire-pulse.service For now, the cgroup mode only works with BPF (-b). Committer notes: Remove -g as it is used in the other tools with a clear meaning of collect/show callchains. As agreed with Namhyung off list. Reviewed-by: Ian Rogers <irogers@google.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230906174903.346486-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-09-12perf lock contention: Prepare to handle cgroupsNamhyung Kim1-1/+25
Save cgroup info and display cgroup names if requested. This is a preparation for the next patch. Reviewed-by: Ian Rogers <irogers@google.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230906174903.346486-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-04-06perf map: Add helper for ->map_ip() and ->unmap_ip()Ian Rogers1-2/+2
Later changes will add reference count checking for struct map, add a helper function to invoke the map_ip and unmap_ip function pointers. The helper allows the reference count check to be in fewer places. Committer notes: Add missing conversions to: tools/perf/util/map.c tools/perf/util/cs-etm.c tools/perf/util/annotate.c tools/perf/arch/powerpc/util/sym-handling.c tools/perf/arch/s390/annotate/instructions.c Signed-off-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Darren Hart <dvhart@infradead.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Dmitriy Vyukov <dvyukov@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: German Gomez <german.gomez@arm.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Clark <james.clark@arm.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: John Garry <john.g.garry@oracle.com> Cc: Kajol Jain <kjain@linux.ibm.com> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Leo Yan <leo.yan@linaro.org> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Miaoqian Lin <linmq006@gmail.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Riccardo Mancini <rickyman7@gmail.com> Cc: Shunsuke Nakamura <nakamura.shun@fujitsu.com> Cc: Song Liu <song@kernel.org> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Brennan <stephen.s.brennan@oracle.com> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas Richter <tmricht@linux.ibm.com> Cc: Yury Norov <yury.norov@gmail.com> Link: https://lore.kernel.org/r/20230404205954.2245628-2-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-04-06perf lock contention: Revise needs_callstack() conditionNamhyung Kim1-1/+1
It needs callstacks for two reasons: * for stack aggregation mode, the map key is the stack id and it can also show the full stack traces when -v is used * for other aggregation modes, the stack filter can be used to limit lock contentions from known call paths The -v option is meaningful (in terms of stack trace) only for stack aggregation mode, so it should not set the save_callstack for other mode like with -t or -l options. I've noticed this with the following command line: $ sudo ./perf lock con -ablv -E 3 -M 16 -- ./perf bench sched messaging ... contended total wait max wait avg wait address symbol 88 4.59 ms 108.07 us 52.13 us ffff935757f46ec0 (spinlock) 33 905.22 us 73.67 us 27.43 us ffff935757f41700 (spinlock) 28 703.69 us 79.28 us 25.13 us ffff938a3d9b0c80 rq_lock (spinlock) === output for debug === bad: 12272, total: 12421 bad rate: 98.80 % histogram of failure reasons task: 8285 stack: 3987 <---------- here time: 0 data: 0 It should not have any failure on stacks since it doesn't use it. No functional change intended. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230406210611.1622492-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-04-06perf lock contention: Update total/bad stats for hidden entriesNamhyung Kim1-1/+3
When -E option is used, it only prints the given number of entries but the event stat at the end should have the numbers for entire entries. Likewise, -S option will hide entries that don't have the named function in the callstack. Also update event stat for them. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230406210611.1622492-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-04-06perf lock contention: Add data failure statNamhyung Kim1-0/+1
It's possible to fail to update the data when the lock_stat map is full. We should check that case and show the number at the end. $ sudo ./perf lock con -ablv -E3 -- ./perf bench sched messaging ... contended total wait max wait avg wait address symbol 6157 208.48 ms 69.29 us 33.86 us ffff934c001c1f00 (spinlock) 4030 72.04 ms 61.84 us 17.88 us ffff934c000415c0 (spinlock) 3201 50.30 ms 47.73 us 15.71 us ffff934c2eead850 (spinlock) === output for debug === bad: 0, total: 13388 bad rate: 0.00 % histogram of failure reasons task: 0 stack: 0 time: 0 data: 0 <----- added Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230406210611.1622492-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-04-04perf maps: Remove rb_node from struct mapIan Rogers1-1/+1
struct map is reference counted, having it also be a node in an red-black tree complicates the reference counting. Switch to having a map_rb_node which is a red-block tree node but points at the reference counted struct map. This reference is responsible for a single reference count. Committer notes: Fixed up tools/perf/util/unwind-libunwind-local.c to use map_rb_node as well. Signed-off-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Darren Hart <dvhart@infradead.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Dmitriy Vyukov <dvyukov@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: German Gomez <german.gomez@arm.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Clark <james.clark@arm.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: John Garry <john.g.garry@oracle.com> Cc: Kajol Jain <kjain@linux.ibm.com> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Leo Yan <leo.yan@linaro.org> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Miaoqian Lin <linmq006@gmail.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Riccardo Mancini <rickyman7@gmail.com> Cc: Shunsuke Nakamura <nakamura.shun@fujitsu.com> Cc: Song Liu <song@kernel.org> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Brennan <stephen.s.brennan@oracle.com> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas Richter <tmricht@linux.ibm.com> Cc: Yury Norov <yury.norov@gmail.com> Link: https://lore.kernel.org/r/20230320212248.1175731-2-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-04-04perf lock contention: Show detail failure reason for BPFNamhyung Kim1-1/+3
It can fail to collect lock stat from BPF for various reasons. For example, I've got a report that sometimes time calculation seems wrong in case of contended spinlocks. I suspect the time delta went negative for some reason. Count them separately and show in the output like below: $ sudo perf lock contention -abE5 sleep 10 contended total wait max wait avg wait type caller 13 785.61 us 79.36 us 60.43 us spinlock remove_wait_queue+0x14 10 469.02 us 87.51 us 46.90 us spinlock prepare_to_wait+0x27 9 289.09 us 69.08 us 32.12 us spinlock finish_wait+0x36 114 251.05 us 8.56 us 2.20 us spinlock try_to_wake_up+0x1f5 132 188.63 us 5.01 us 1.43 us spinlock __wake_up_common_lock+0x62 === output for debug === bad: 1, total: 279 bad rate: 0.36 % histogram of failure reasons task: 1 stack: 0 time: 0 Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230327225711.245738-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-04-04perf lock contention: Fix msan issue in lock_contention_read()Namhyung Kim1-1/+1
I got a report of a msan failure like below: $ sudo perf lock con -ab -- sleep 1 ... ==224416==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x5651160d6c96 in lock_contention_read util/bpf_lock_contention.c:290:8 #1 0x565115f90870 in __cmd_contention builtin-lock.c:1919:3 #2 0x565115f90870 in cmd_lock builtin-lock.c:2385:8 #3 0x565115f03a83 in run_builtin perf.c:330:11 #4 0x565115f03756 in handle_internal_command perf.c:384:8 #5 0x565115f02d53 in run_argv perf.c:428:2 #6 0x565115f02d53 in main perf.c:562:3 #7 0x7f43553bc632 in __libc_start_main #8 0x565115e865a9 in _start It was because the 'key' variable is not initialized. Actually it'd be set by bpf_map_get_next_key() but msan didn't seem to understand it. Let's make msan happy by initializing the variable. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20230324001922.937634-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-03-14perf lock contention: Show per-cpu rq_lock with addressNamhyung Kim1-2/+25
Using the BPF_PROG_RUN mechanism, we can run a raw_tp BPF program to collect some semi-global locks like per-cpu locks. Let's add runqueue locks using bpf_per_cpu_ptr() helper. $ sudo ./perf lock con -abl -- sleep 1 contended total wait max wait avg wait address symbol 248 3.25 ms 32.23 us 13.10 us ffff8cc75cfd2940 siglock 60 217.91 us 9.69 us 3.63 us ffff8cc700061c00 8 70.23 us 13.86 us 8.78 us ffff8cc703629484 4 56.32 us 35.81 us 14.08 us ffff8cc78b66f778 mmap_lock 4 16.70 us 5.18 us 4.18 us ffff8cc7036a0684 3 4.99 us 2.65 us 1.66 us ffff8d053da30c80 rq_lock 2 3.44 us 2.28 us 1.72 us ffff8d053dcf0c80 rq_lock 9 2.51 us 371 ns 278 ns ffff8ccb92479440 2 2.11 us 1.24 us 1.06 us ffff8d053db30c80 rq_lock 2 2.06 us 1.69 us 1.03 us ffff8d053d970c80 rq_lock Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: Stephane Eranian <eranian@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230313204825.2665483-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-03-14perf lock contention: Track and show siglock with addressNamhyung Kim1-2/+6
Likewise, we can display siglock by following the pointer like current->sighand->siglock. $ sudo ./perf lock con -abl -- sleep 1 contended total wait max wait avg wait address symbol 16 2.18 ms 305.35 us 136.34 us ffffffff92e06080 tasklist_lock 28 521.78 us 31.16 us 18.63 us ffff8cc703783ec4 7 119.03 us 23.55 us 17.00 us ffff8ccb92479440 15 88.29 us 10.06 us 5.89 us ffff8cd560b5f380 siglock 7 37.67 us 9.16 us 5.38 us ffff8d053daf0c80 5 8.81 us 4.92 us 1.76 us ffff8d053d6b0c80 Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Hao Luo <haoluo@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: Stephane Eranian <eranian@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230313204825.2665483-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-02-08perf lock contention: Add -o/--lock-owner optionNamhyung Kim1-0/+1
When there're many lock contentions in the system, people sometimes want to know who caused the contention, IOW who's the owner of the locks. The -o/--lock-owner option tries to follow the lock owners for the contended mutexes and rwsems from BPF, and then attributes the contention time to the owner instead of the waiter. It's a best effort approach to get the owner info at the time of the contention and doesn't guarantee to have the precise tracking of owners if it's changing over time. Currently it only handles mutex and rwsem that have owner field in their struct and it basically points to a task_struct that owns the lock at the moment. Technically its type is atomic_long_t and it comes with some LSB bits used for other meanings. So it needs to clear them when casting it to a pointer to task_struct. Also the atomic_long_t is a typedef of the atomic 32 or 64 bit types depending on arch which is a wrapper struct for the counter value. I'm not aware of proper ways to access those kernel atomic types from BPF so I just read the internal counter value directly. Please let me know if there's a better way. When -o/--lock-owner option is used, it goes to the task aggregation mode like -t/--threads option does. However it cannot get the owner for other lock types like spinlock and sometimes even for mutex. $ sudo ./perf lock con -abo -- ./perf bench sched pipe # Running 'sched/pipe' benchmark: # Executed 1000000 pipe operations between two processes Total time: 4.766 [sec] 4.766540 usecs/op 209795 ops/sec contended total wait max wait avg wait pid owner 403 565.32 us 26.81 us 1.40 us -1 Unknown 4 27.99 us 8.57 us 7.00 us 1583145 sched-pipe 1 8.25 us 8.25 us 8.25 us 1583144 sched-pipe 1 2.03 us 2.03 us 2.03 us 5068 chrome As you can see, the owner is unknown for the most cases. But if we filter only for the mutex locks, it'd more likely get the onwers. $ sudo ./perf lock con -abo -Y mutex -- ./perf bench sched pipe # Running 'sched/pipe' benchmark: # Executed 1000000 pipe operations between two processes Total time: 4.910 [sec] 4.910435 usecs/op 203647 ops/sec contended total wait max wait avg wait pid owner 2 15.50 us 8.29 us 7.75 us 1582852 sched-pipe 7 7.20 us 2.47 us 1.03 us -1 Unknown 1 6.74 us 6.74 us 6.74 us 1582851 sched-pipe Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230207002403.63590-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-02-03perf lock contention: Support filters for different aggregationNamhyung Kim1-14/+30
It'd be useful to filter other than the current aggregation mode. For example, users may want to see callstacks for specific locks only. Or they may want tasks from a certain callstack. The tracepoints already collected the information but it needs to check the condition again when processing the event. And it needs to change BPF to allow the key combinations. The lock contentions on 'rcu_state' spinlock can be monitored: $ sudo perf lock con -abv -L rcu_state sleep 1 ... contended total wait max wait avg wait type caller 4 151.39 us 62.57 us 37.85 us spinlock rcu_core+0xcb 0xffffffff81fd1666 _raw_spin_lock_irqsave+0x46 0xffffffff8172d76b rcu_core+0xcb 0xffffffff822000eb __softirqentry_text_start+0xeb 0xffffffff816a0ba9 __irq_exit_rcu+0xc9 0xffffffff81fc0112 sysvec_apic_timer_interrupt+0xa2 0xffffffff82000e46 asm_sysvec_apic_timer_interrupt+0x16 0xffffffff81d49f78 cpuidle_enter_state+0xd8 0xffffffff81d4a259 cpuidle_enter+0x29 1 30.21 us 30.21 us 30.21 us spinlock rcu_core+0xcb 0xffffffff81fd1666 _raw_spin_lock_irqsave+0x46 0xffffffff8172d76b rcu_core+0xcb 0xffffffff822000eb __softirqentry_text_start+0xeb 0xffffffff816a0ba9 __irq_exit_rcu+0xc9 0xffffffff81fc00c4 sysvec_apic_timer_interrupt+0x54 0xffffffff82000e46 asm_sysvec_apic_timer_interrupt+0x16 1 28.84 us 28.84 us 28.84 us spinlock rcu_accelerate_cbs_unlocked+0x40 0xffffffff81fd1c60 _raw_spin_lock+0x30 0xffffffff81728cf0 rcu_accelerate_cbs_unlocked+0x40 0xffffffff8172da82 rcu_core+0x3e2 0xffffffff822000eb __softirqentry_text_start+0xeb 0xffffffff816a0ba9 __irq_exit_rcu+0xc9 0xffffffff81fc0112 sysvec_apic_timer_interrupt+0xa2 0xffffffff82000e46 asm_sysvec_apic_timer_interrupt+0x16 0xffffffff81d49f78 cpuidle_enter_state+0xd8 ... To see tasks calling 'rcu_core' function: $ sudo perf lock con -abt -S rcu_core sleep 1 contended total wait max wait avg wait pid comm 19 23.46 us 2.21 us 1.23 us 0 swapper 2 18.37 us 17.01 us 9.19 us 2061859 ThreadPoolForeg 3 5.76 us 1.97 us 1.92 us 3909 pipewire-pulse 1 2.26 us 2.26 us 2.26 us 1809271 MediaSu~isor #2 1 1.97 us 1.97 us 1.97 us 1514882 Chrome_ChildIOT 1 987 ns 987 ns 987 ns 3740 pipewire-pulse Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230203021324.143540-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-02-03perf lock contention: Use lock_stat_find{,new}Namhyung Kim1-16/+25
This is a preparation work to support complex keys of BPF maps. Now it has single value key according to the aggregation mode like stack_id or pid. But we want to use a combination of those keys. Then lock_contention_read() should still aggregate the result based on the key that was requested by user. The other key info will be used for filtering. So instead of creating a lock_stat entry always, Check if it's already there using lock_stat_find() first. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230203021324.143540-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-02-03perf lock contention: Factor out lock_contention_get_name()Namhyung Kim1-50/+65
The lock_contention_get_name() returns a name for the lock stat entry based on the current aggregation mode. As it's called sequentially in a single thread, it can return the address of a static buffer for symbol and offset of the caller. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230203021324.143540-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-02-02perf lock contention: Add -S/--callstack-filter optionNamhyung Kim1-1/+1
The -S/--callstack-filter is to limit display entries having the given string in the callstack (not only in the caller in the output). The following example shows lock contention results if the callstack has 'net' substring somewhere. Note that the caller '__dev_queue_xmit' does not match to it, but it has 'inet6_csk_xmit' in the callstack. This applies even if you don't use -v option to show the full callstack. $ sudo ./perf lock con -abv -S net sleep 1 ... contended total wait max wait avg wait type caller 5 70.20 us 16.13 us 14.04 us spinlock __dev_queue_xmit+0xb6d 0xffffffffa5dd1c60 _raw_spin_lock+0x30 0xffffffffa5b8f6ed __dev_queue_xmit+0xb6d 0xffffffffa5cd8267 ip6_finish_output2+0x2c7 0xffffffffa5cdac14 ip6_finish_output+0x1d4 0xffffffffa5cdb477 ip6_xmit+0x457 0xffffffffa5d1fd17 inet6_csk_xmit+0xd7 0xffffffffa5c5f4aa __tcp_transmit_skb+0x54a 0xffffffffa5c6467d tcp_keepalive_timer+0x2fd Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230126000936.3017683-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-21perf lock contention: Support lock addr/name filtering for BPFNamhyung Kim1-1/+41
Likewise, add addr_filter BPF hash map and check it with the lock address. $ sudo ./perf lock con -ab -L tasklist_lock -- ./perf bench sched messaging # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 10 groups == 400 processes run Total time: 0.169 [sec] contended total wait max wait avg wait type caller 18 174.09 us 25.31 us 9.67 us rwlock:W do_exit+0x36d 5 32.34 us 10.87 us 6.47 us rwlock:R do_wait+0x8b 4 15.41 us 4.73 us 3.85 us rwlock:W release_task+0x6e Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221219201732.460111-6-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-21perf lock contention: Support lock type filtering for BPFNamhyung Kim1-1/+14
Likewise, add type_filter BPF hash map and check it when user gave a lock type filter. $ sudo ./perf lock con -ab -Y rwlock -- ./perf bench sched messaging # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 10 groups == 400 processes run Total time: 0.203 [sec] contended total wait max wait avg wait type caller 15 156.19 us 19.45 us 10.41 us rwlock:W do_exit+0x36d 1 11.12 us 11.12 us 11.12 us rwlock:R do_wait+0x8b 1 5.09 us 5.09 us 5.09 us rwlock:W release_task+0x6e Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221219201732.460111-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-20perf tools: Fix usage of the verbose variableYang Jihong1-1/+1
The data type of the verbose variable is integer and can be negative, replace improperly used cases in a unified manner: 1. if (verbose) => if (verbose > 0) 2. if (!verbose) => if (verbose <= 0) 3. if (XX && verbose) => if (XX && verbose > 0) 4. if (XX && !verbose) => if (XX && verbose <= 0) Reviewed-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Yang Jihong <yangjihong1@huawei.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Carsten Haitzler <carsten.haitzler@arm.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Martin KaFai Lau <martin.lau@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Link: https://lore.kernel.org/r/20221220035702.188413-3-yangjihong1@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-14perf lock contention: Add -l/--lock-addr optionNamhyung Kim1-6/+17
The -l/--lock-addr option is to implement per-lock-instance contention stat using LOCK_AGGR_ADDR. It displays lock address and optionally symbol name if exists. $ sudo ./perf lock con -abl sleep 1 contended total wait max wait avg wait address symbol 1 36.28 us 36.28 us 36.28 us ffff92615d6448b8 9 10.91 us 1.84 us 1.21 us ffffffffbaed50c0 rcu_state 1 10.49 us 10.49 us 10.49 us ffff9262ac4f0c80 8 4.68 us 1.67 us 585 ns ffffffffbae07a40 jiffies_lock 3 3.03 us 1.45 us 1.01 us ffff9262277861e0 1 924 ns 924 ns 924 ns ffff926095ba9d20 1 436 ns 436 ns 436 ns ffff9260bfda4f60 Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221209190727.759804-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-14perf lock contention: Implement -t/--threads option for BPFNamhyung Kim1-3/+37
The BPF didn't show the per-thread stat properly. Use task's thread id (PID) as a key instead of stack_id and add a task_data map to save task comm names. $ sudo ./perf lock con -abt -E 5 sleep 1 contended total wait max wait avg wait pid comm 1 740.66 ms 740.66 ms 740.66 ms 1950 nv_queue 3 305.50 ms 298.19 ms 101.83 ms 1884 nvidia-modeset/ 1 25.14 us 25.14 us 25.14 us 2725038 EventManager_De 12 23.09 us 9.30 us 1.92 us 0 swapper 1 20.18 us 20.18 us 20.18 us 2725033 EventManager_De Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221209190727.759804-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-14perf lock contention: Add lock_data.h for common dataNamhyung Kim1-13/+6
Accessing BPF maps should use the same data types. Add bpf_skel/lock_data.h to define the common data structures. No functional changes. Committer notes: Fixed contention_key.stack_id missing rename to contention_key.stack_or_task_id. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221209190727.759804-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-14machine: Adopt is_lock_function() from builtin-lock.cArnaldo Carvalho de Melo1-1/+1
It is used in bpf_lock_contention.c and builtin-lock.c will be made CONFIG_LIBTRACEEVENT=y conditional, so move it to machine.c, that is always available. This makes those 4 global variables for sched and lock text start and end to move to 'struct machine' too, as conceivably we can have that info for several machine instances, say some 'perf diff' like tool. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: bpf@vger.kernel.org Link: http://lore.kernel.org/lkml/ Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-11-23perf lock contention: Do not use BPF task local storageNamhyung Kim1-0/+1
It caused some troubles when a lock inside kmalloc is contended because task local storage would allocate memory using kmalloc. It'd create a recusion and even crash in my system. There could be a couple of workarounds but I think the simplest one is to use a pre-allocated hash map. We could fix the task local storage to use the safe BPF allocator, but it takes time so let's change this until it happens actually. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Chris Li <chriscli@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221118190109.1512674-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-31perf lock contention: Avoid variable length arraysNamhyung Kim1-13/+28
The msan also warns about the use of VLA for stack_trace variable. We can dynamically allocate instead. While at it, simplify the error handle a bit (and fix bugs). Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20221028180128.3311491-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-31perf lock contention: Fix memory sanitizer issueNamhyung Kim1-1/+1
The msan reported a use-of-uninitialized-value warning for the struct lock_contention_data in lock_contention_read(). While it'd be filled by bpf_map_lookup_elem(), let's just initialize it to silence the warning. ==12524==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x562b0f16b1cd in lock_contention_read util/bpf_lock_contention.c:139:7 #1 0x562b0ef65ec6 in __cmd_contention builtin-lock.c:1737:3 #2 0x562b0ef65ec6 in cmd_lock builtin-lock.c:1992:8 #3 0x562b0ee7f50b in run_builtin perf.c:322:11 #4 0x562b0ee7efc1 in handle_internal_command perf.c:376:8 #5 0x562b0ee7e1e9 in run_argv perf.c:420:2 #6 0x562b0ee7e1e9 in main perf.c:550:3 #7 0x7f065f10e632 in __libc_start_main (/usr/lib64/libc.so.6+0x61632) #8 0x562b0edf2fa9 in _start (perf+0xfa9) SUMMARY: MemorySanitizer: use-of-uninitialized-value (perf+0xe15160) in lock_contention_read Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20221028180128.3311491-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-06perf lock: Remove unused struct lock_contention_keyYuan Can1-5/+0
The struct lock_contention_key is never used, remove it. Signed-off-by: Yuan Can <yuancan@huawei.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/linux-perf-users/20220927013931.110475-6-yuancan@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-04perf lock contention: Skip stack trace from BPFNamhyung Kim1-3/+4
Currently it collects stack traces to max size then skip entries. Because we don't have control how to skip perf callchains. But BPF can do it with bpf_get_stackid() with a flag. Say we have max-stack=4 and stack-skip=2, we get these stack traces. Before: After: .---> +---+ <--. .---> +---+ <--. | | | | | | | | | +---+ usable | +---+ | max | | | max | | | stack +---+ <--' stack +---+ usable | | X | | | | | | +---+ skip | +---+ | | | X | | | | | `---> +---+ `---> +---+ <--' <=== collection | X | +---+ skip | X | +---+ Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <songliubraving@fb.com> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20220912055314.744552-5-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-04perf lock contention: Allow to change stack depth and skipNamhyung Kim1-3/+4
It needs stack traces to find callers of locks. To minimize the performance overhead it only collects up to 8 entries for each stack trace. And it skips first 3 entries as they came from BPF, tracepoint and lock functions which are not interested for most users. But it turned out that those numbers are different in some configuration. Using fixed number can result in non meaningful caller names. Let's make them adjustable with --stack-depth and --skip-stack options. On my setup, the default output is like below: # /perf lock con -ab -F contended,wait_total sleep 3 contended total wait type caller 28 4.55 ms rwlock:W __bpf_trace_contention_begin+0xb 33 1.67 ms rwlock:W __bpf_trace_contention_begin+0xb 12 580.28 us