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It was reported that it failed to build the BPF lock contention skeleton
on 32 bit arch due to the size of long. The lost count is used only for
reporting errors due to lack of stackmap space through bad_hist which
type is 'int'. Let's use int type then.
Fixes: 6d499a6b3d90277d ("perf lock: Print the number of lost entries for BPF")
Reported-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Link: http://lore.kernel.org/lkml/20220926215638.3931222-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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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 spinlock __bpf_trace_contention_begin+0xb
60 240.54 us rwsem:R __bpf_trace_contention_begin+0xb
27 64.45 us spinlock __bpf_trace_contention_begin+0xb
If I change the stack skip to 5, the result will be like:
# perf lock con -ab -F contended,wait_total --stack-skip 5 sleep 3
contended total wait type caller
32 715.45 us spinlock folio_lruvec_lock_irqsave+0x61
26 550.22 us spinlock folio_lruvec_lock_irqsave+0x61
15 486.93 us rwsem:R mmap_read_lock+0x13
12 139.66 us rwsem:W vm_mmap_pgoff+0x93
1 7.04 us spinlock tick_do_update_jiffies64+0x25
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/20220912055314.744552-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Currently it shows a caller function for each entry, but users need to see
the full call stacks sometimes. Use -v/--verbose option to do that.
# perf lock con -a -b -v sleep 3
Looking at the vmlinux_path (8 entries long)
symsrc__init: cannot get elf header.
Using /proc/kcore for kernel data
Using /proc/kallsyms for symbols
contended total wait max wait avg wait type caller
1 10.74 us 10.74 us 10.74 us spinlock __bpf_trace_contention_begin+0xb
0xffffffffc03b5c47 bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117
0xffffffffc03b5c47 bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117
0xffffffffbb8b8e75 bpf_trace_run2+0x35
0xffffffffbb7eab9b __bpf_trace_contention_begin+0xb
0xffffffffbb7ebe75 queued_spin_lock_slowpath+0x1f5
0xffffffffbc1c26ff _raw_spin_lock+0x1f
0xffffffffbb841015 tick_do_update_jiffies64+0x25
0xffffffffbb8409ee tick_irq_enter+0x9e
1 7.70 us 7.70 us 7.70 us spinlock __bpf_trace_contention_begin+0xb
0xffffffffc03b5c47 bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117
0xffffffffc03b5c47 bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117
0xffffffffbb8b8e75 bpf_trace_run2+0x35
0xffffffffbb7eab9b __bpf_trace_contention_begin+0xb
0xffffffffbb7ebe75 queued_spin_lock_slowpath+0x1f5
0xffffffffbc1c26ff _raw_spin_lock+0x1f
0xffffffffbb7bc27e raw_spin_rq_lock_nested+0xe
0xffffffffbb7cef9c load_balance+0x66c
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/20220912055314.744552-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Like the normal 'perf lock contention' output, it'd print the number of
lost entries for BPF if exists or -v option is passed.
Currently it uses BROKEN_CONTENDED stat for the lost count (due to full
stack maps).
$ sudo perf lock con -a -b --map-nr-entries 128 sleep 5
...
=== output for debug===
bad: 43, total: 14903
bad rate: 0.29 %
histogram of events caused bad sequence
acquire: 0
acquired: 0
contended: 43
release: 0
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Blake Jones <blakejones@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220802191004.347740-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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The --map-nr-entries option is to control number of max entries in the
perf lock contention BPF maps.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Blake Jones <blakejones@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220802191004.347740-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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The lock_contention struct is to carry related fields together and to
minimize the change when we add new config options.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Blake Jones <blakejones@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220802191004.347740-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Add -a/--all-cpus and -C/--cpu options for cpu filtering. Also -p/--pid
and --tid options are added for task filtering. The short -t option is
taken for --threads already. Tracking the command line workload is
possible as well.
$ sudo perf lock contention -a -b sleep 1
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Blake Jones <blakejones@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Stephane Eranian <eranian@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220729200756.666106-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Add -b/--use-bpf option to use BPF to collect lock contention stats.
For simplicity it now runs system-wide and requires C-c to stop.
Upcoming changes will add the usual filtering.
$ sudo perf lock con -b
^C
contended total wait max wait avg wait type caller
42 192.67 us 13.64 us 4.59 us spinlock queue_work_on+0x20
23 85.54 us 10.28 us 3.72 us spinlock worker_thread+0x14a
6 13.92 us 6.51 us 2.32 us mutex kernfs_iop_permission+0x30
3 11.59 us 10.04 us 3.86 us mutex kernfs_dop_revalidate+0x3c
1 7.52 us 7.52 us 7.52 us spinlock kthread+0x115
1 7.24 us 7.24 us 7.24 us rwlock:W sys_epoll_wait+0x148
2 7.08 us 3.99 us 3.54 us spinlock delayed_work_timer_fn+0x1b
1 6.41 us 6.41 us 6.41 us spinlock idle_balance+0xa06
2 2.50 us 1.83 us 1.25 us mutex kernfs_iop_lookup+0x2f
1 1.71 us 1.71 us 1.71 us mutex kernfs_iop_getattr+0x2c
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Blake Jones <blakejones@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
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: Stephane Eranian <eranian@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220729200756.666106-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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