Subject: Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

From: Alexei Starovoitov <[email-masked]>
Date: Wed, 21 Oct 2015 20:09:19 -0700

On 10/21/15 6:56 PM, Wangnan (F) wrote:
>> One alternative solution I can image is to attach a BPF program
>> at sampling like kprobe, and return 0 if we don't want sampling
>> take action. Thought?
>
> Do you think attaching BPF programs to sampling is an acceptable idea?

If you mean to extend 'filter' concept to sampling events?
So instead of soft_disable of non-local events, you'll attach bpf
program to sampling events and use map lookup to decide whether
to filter out or not such sampling event?
What pt_regs would be in such case?