tcppktlat: Add histogram mode with per-PID grouping #5430
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ethercflow
requested review from
brendangregg,
chenhengqi,
ekyooo and
yonghong-song
as code owners
ekyooo
reviewed
Nov 28, 2025
libbpf-tools/tcppktlat_example.txt
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| Trace latency between TCP received pkt and picked up by userspace thread. | ||
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| USAGE: tcppktlat [--help] [-T] [-p PID] [-t TID] [-l LPORT] [-r RPORT] [-v] | ||
| USAGE: tcppktlat [--help] [-T] [-H] [-p PID] [-t TID] [-l LPORT] [-r RPORT] [-w] [-v] |
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The USAGE description in tcppktlat_example.txt is inconsistent with the actual implementation in tcppktlat. c
libbpf-tools/tcppktlat.c
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| env.histogram = true; | ||
| if (arg) { | ||
| errno = 0; | ||
| env.interval = strtoul(arg, NULL, 10); |
Collaborator
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The -H option allows specifying interval both as an optional argument and as a positional argument, which creates ambiguity.
| fprintf(stderr, "Invalid delay (in us): %s\n", arg); | ||
| argp_usage(state); | ||
| if (env.histogram) { | ||
| /* For histogram mode, positional args are interval and count */ |
Collaborator
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Positional argument behavior depends on -H, but this is unclear in the help message.
libbpf-tools/tcppktlat.bpf.c
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| hkey = pid; | ||
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| histp = bpf_map_lookup_or_try_init(&hists, &hkey, &zero); | ||
| if (histp) { |
Collaborator
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Explicit error handling would be preferable, similar to the else case. For example:
if (!histp)
goto cleanup;
Add -H option to display latency as histograms grouped by PID. Supports periodic printing with interval argument and works with existing filters like -p, -t, -l, -r. Signed-off-by: Wenbo Zhang <[email protected]>
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Author
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@ekyooo addressed, thx! |
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Add -H option to display latency as histograms grouped by PID. Supports periodic printing with interval argument and works with existing filters like -p, -t, -l, -r.