ring-buffer: Redefine the unimplemented RINGBUF_TYPE_TIME_STAMP

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RINGBUF_TYPE_TIME_STAMP is defined but not used, and from what I can
gather was reserved for something like an absolute timestamp feature
for the ring buffer, if not a complete replacement of the current
time_delta scheme.

This code redefines RINGBUF_TYPE_TIME_STAMP to implement absolute time
stamps.  Another way to look at it is that it essentially forces
extended time_deltas for all events.

The motivation for doing this is to enable time_deltas that aren't
dependent on previous events in the ring buffer, making it feasible to
use the ring_buffer_event timetamps in a more random-access way, for
purposes other than serial event printing.

To set/reset this mode, use tracing_set_timestamp_abs() from the
previous interface patch.

Link: http://lkml.kernel.org/r/477b362dba1ce7fab9889a1a8e885a62c472f041.1516069914.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

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This commit is contained in:

Tom Zanussi 2018-01-15 20:51:40 -06:00 • committed by Steven Rostedt (VMware)

parent 00b4145298

commit dc4e2801d4

2 changed files with 83 additions and 33 deletions

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12

include/linux/ring_buffer.h

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104

kernel/trace/ring_buffer.c

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