Re: Why is BPF_PERF_OUTPUT max_entries set to total processor count?

Yonghong Song

PERF_EVENT_OUTPUT map is to hold per cpu ring buffers created by
That is why its typical size is the number of cpus on the host.

On Sun, Feb 16, 2020 at 1:52 AM Hayden Livingston
<halivingston@...> wrote:

I'm very confused why BCC creates a map of number of processors for
the perf_events output map.

I can imagine it being 1 since all it does is act as a kernel-user
mode intermediary and it is true that the code cannot be preempted.

Or if it can be preempted then I can imagine that since there can't be
more than processor count it is the max depth one has to worry about.

Is my thinking flawed? Or maybe there is a completely different reason?

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