libbpf-tools/offcputime: Allow offcputime to run on old kernels #4334
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woodpenker
requested review from
drzaeus77,
goldshtn,
yonghong-song,
4ast,
brendangregg and
davemarchevsky
as code owners
| } | ||
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| SEC("kprobe/finish_task_switch") | ||
| int BPF_PROG(sched_switch_tp) { |
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Let's fallback to raw tracepoint instead. See #4217.
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Thanks for replay, but on my test env, the "raw_tp/sched_switch" won't work:
libbpf: sched_switch is not found in vmlinux BTF
entries_lock
failed to get syms
- (0)
51
entries_lock
failed to get syms
- (0)
4811
entries_lock
The comm is empty and PID is always 0, I think the prev is not correctly taken. Do you have any suggest?
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Let's fallback to raw tracepoint instead. See #4217.
I tried to make it work and succeed, but the call stacks still seem always belong to the tracepoint raw_tp/sched_switch.
Changed code:
SEC("raw_tp/sched_switch")
int BPF_PROG(sched_switch_tp) {
struct task_struct *prev = (struct task_struct *)((struct bpf_raw_tracepoint_args *)ctx)->args[1];
return handle_switch(ctx, prev);
}Output example:
entries_lock [250/15106]
- kworker/2:2 (2704182)
9
entries_lock
wait4
- bash (2708107)
13
entries_lock
- ksoftirqd/0 (10)
1
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Does #4217 work for you ?
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Does #4217 work for you ?
Everything works fine except the callstacks, so close this pr until I find the reason and solutions。
libbpf-tools/offcputime.c
Outdated
| if (probe_tp_btf("sched_switch")) { | ||
| bpf_program__set_autoload(obj->progs.sched_switch_tp, false); | ||
| } else { | ||
| bpf_program__set_autoload(obj->progs.sched_switch_btf, false); | ||
| } |
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We are following kernel code style guide, so drop the surrounding {}.
woodpenker
changed the title
Allow offcputime to run on old kernels according to #4231.
Test OK on Ubuntu with 5.4.0 kernel.