Does a scheduler trace show anything about why that drop happens? Do
something like this to trace the scheduler:
assuming debugfs is mounted under /debug and CONFIG_SCHED_TRACER=y:
echo 1 > /debug/tracing/tracing_cpumask
echo sched_switch > /debug/tracing/available_tracers
cat /debug/tracing/trace_pipe > trace.txt
( regarding tracing_cpumask: trace only 1 CPU to make sure volanomark is
not disturbed too much by many-CPUs tracing. )
Ingo
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