Re: CPU Concurrency Issues
On Tue, Aug 20, 2019 at 12:05 PM Arnaldo Carvalho de Melo
You did not miss anything. Currently, there are no counters to count those
drops due to nmi or due to bpf program already running on that cpu.
There is effort by Daniel Xu to expose nhit/nmisses counters
from k/uprobe trace infra. Even kprobe is not a miss, bpf program may not
fire due to the above reasons.
debugfs has k/uprobe_profile to count nhit/nmisses from k/uprobe trace infra.
We could add a counter into trace_event_call->event to count hit/miss. The hit
can also be counted by bpf program itself. The "miss" should be rare, and
most bpf programs e.g. in bcc are designed to tolerate occasional probe miss,
which should not affect much on the final aggregation results.
How strongly do you feel such a bpf prog hit/miss counter for tracing programs