b44d665368
Currently it accounts the contention using delta between timestamps in
lock:contention_begin and lock:contention_end tracepoints. But it means
the lock should see the both events during the monitoring period.
Actually there are 4 cases that happen with the monitoring:
monitoring period
/ \
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1: B------+-----------------------+--------E
2: B----+-------------E |
3: | B-----------+----E
4: | B-------------E |
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t0 t1
where B and E mean contention BEGIN and END, respectively. So it only
accounts the case 4 for now. It seems there's no way to handle the case
1. The case 2 might be handled if it saved the timestamp (t0), but it
lacks the information from the B notably the flags which shows the lock
types. Also it could be a nested lock which it currently ignores. So
I think we should ignore the case 2.
However we can handle the case 3 if we save the timestamp (t1) at the
end of the period. And then it can iterate the map entries in the
userspace and update the lock stat accordinly.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Reviwed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20240228053335.312776-1-namhyung@kernel.org
58 lines
1.0 KiB
C
58 lines
1.0 KiB
C
// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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/* Data structures shared between BPF and tools. */
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#ifndef UTIL_BPF_SKEL_LOCK_DATA_H
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#define UTIL_BPF_SKEL_LOCK_DATA_H
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struct tstamp_data {
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u64 timestamp;
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u64 lock;
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u32 flags;
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u32 stack_id;
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};
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struct contention_key {
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u32 stack_id;
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u32 pid;
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u64 lock_addr_or_cgroup;
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};
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#define TASK_COMM_LEN 16
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struct contention_task_data {
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char comm[TASK_COMM_LEN];
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};
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/* default buffer size */
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#define MAX_ENTRIES 16384
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/*
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* Upper bits of the flags in the contention_data are used to identify
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* some well-known locks which do not have symbols (non-global locks).
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*/
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#define LCD_F_MMAP_LOCK (1U << 31)
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#define LCD_F_SIGHAND_LOCK (1U << 30)
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#define LCB_F_MAX_FLAGS (1U << 7)
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struct contention_data {
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u64 total_time;
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u64 min_time;
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u64 max_time;
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u32 count;
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u32 flags;
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};
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enum lock_aggr_mode {
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LOCK_AGGR_ADDR = 0,
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LOCK_AGGR_TASK,
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LOCK_AGGR_CALLER,
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LOCK_AGGR_CGROUP,
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};
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enum lock_class_sym {
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LOCK_CLASS_NONE,
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LOCK_CLASS_RQLOCK,
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};
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#endif /* UTIL_BPF_SKEL_LOCK_DATA_H */
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