Expose libbpf_num_possible_cpus #331
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To fetch the number of "possible" (`/sys/devices/system/cpu/possible`) CPUs. This is needed in various PERCPU structures to compute the value size. More details in parca-dev/parca-agent#1696 (comment) Signed-off-by: Francisco Javier Honduvilla Coto <javierhonduco@gmail.com>
| func NumPossibleCPUs() (int, error) { | ||
| numCPUs, _ := C.libbpf_num_possible_cpus() | ||
| if numCPUs < 0 { | ||
| return 0, fmt.Errorf("failed to retrieve the number of CPUs") |
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Sorry for the late review.
Shouldn't this error have errno information? For example:
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Actually it wasn't late and I should have pinged you @geyslan before. I'm sorry! Feel free to fix this with Javier if needed and merge! Sorry again for the fast pace.
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I don't think we need to check for errno here, the only error path from the function is here, but let me know if you think that's not correct
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I don't think we need to check for errno here, the only error path from the function is here, but let me know if you think that's not correct
We standardized returns taking into account possible changes in libbpf. Perhaps currently libbpf does not have a clear set of errno in this function, but it may be different in the future. And above all, as cgo provides us errno in C calls is always good to make use of it.
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@javierhonduco thanks for your contribution. It was shipped in v0.4.9-libbpf-1.2.0. |
To fetch the number of "possible" (
/sys/devices/system/cpu/possible) CPUs.This is needed in various PERCPU structures to compute the value size. More details in parca-dev/parca-agent#1696 (comment)
Fixes: #195