perf script: If type not given fields apply to all event types
Allow: perf script -f <fields> to be equivalent to: perf script -f trace:<fields> -f sw:<fields> -f hw:<fields> i.e., the specified fields apply to all event types if the type string is not given. The field (-f) arguments are processed in the order received. A later usage can reset a prior request. e.g., -f trace: -f comm,tid,time,sym The first -f suppresses trace events (field list is ""), but then the second invocation sets the fields to comm,tid,time,sym. In this case a warning is given to the user: "Overriding previous field request for all events." Alternativey, consider the order: -f comm,tid,time,sym -f trace: The first -f sets the fields for all events and the second -f suppresses trace events. The user is given a warning message about the override, and the result of the above is that only S/W and H/W events are displayed with the given fields. For the 'wildcard' option if a user selected field is invalid for an event type, a message is displayed to the user that the option is ignored for that type. For example: perf script -f comm,tid,trace 2>&1 | less 'trace' not valid for hardware events. Ignoring. 'trace' not valid for software events. Ignoring. Alternatively, if the type is given an invalid field is specified it is an error. For example: perf script -v -f sw:comm,tid,trace 2>&1 | less 'trace' not valid for software events. At this point usage is displayed, and perf-script exits. Finally, a user may not set fields to none for all event types. i.e., -f "" is not allowed. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org LPU-Reference: <1300377801-27246-1-git-send-email-daahern@cisco.com> Signed-off-by: NDavid Ahern <daahern@cisco.com> Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
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