map: Do not chec maxEntries for PerfEventArray map

[olsajiri]

When I use perf event map in MapReplacements for ebpf.CollectionOptions,
I'm getting error for maxEntries check.

The perf event map is created with maxEntries initialized to number
of cpus, so we can't check maxEntries before the map is created.

I'm not sure we can postpone the check, but we can surely skip it
for perf event map.

Signed-off-by: Jiri Olsa jolsa@kernel.org

[lmb]

Ah, good point! We already have a bit of special casing for PerfEventArray:

ebpf/map.go

Lines 381 to 387 in be4d571

	if spec.MaxEntries == 0 {
	n, err := internal.PossibleCPUs()
	if err != nil {
	return nil, fmt.Errorf("perf event array: %w", err)
	}
	spec.MaxEntries = uint32(n)
	}

What if you only skip the check if ms.Type == PerfEventArray && ms.MaxEntries == 0? That way it's in line with the other special case we have.

[olsajiri]

What if you only skip the check if ms.Type == PerfEventArray && ms.MaxEntries == 0? That way it's in line with the other special case we have.

sounds good, will change, thanks

[olsajiri]

@lmb any idea what's wrong with the CI? looks like I can't check results, thanks

[lmb]

Sometimes it gets stuck, I think due to the VM crashing. I've triggered a rerun.