Static tracepoints can also be filtered. When an event matches a filter set, it is kept, otherwise it is discarded. Events without filters are always kept.

For example, to set a matching filter for the log_dbg event inserted in the preceding code, you could match either the a or b variables:

# echo "a == "Hello"" > 
/sys/kernel/debug/tracing/events/log_dbg/log_dbg/filter