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tracing: Add cpu field for hist triggers

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A common key to use in a histogram is the cpuid - add a new cpu
'synthetic' field named 'cpu' for that purpose.

Link: http://lkml.kernel.org/r/89537645bfc957e0d76e2cacf5f0ada88691a6cc.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>
This commit is contained in:
Tom Zanussi
2018-01-15 20:52:03 -06:00
committed by Steven Rostedt (VMware)
parent ec5ce09875
commit 8b7622bf94
2 changed files with 42 additions and 1 deletions
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15
Documentation/trace/histogram.txt
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@@ -172,6 +172,21 @@
The examples below provide a more concrete illustration of the
concepts and typical usage patterns discussed above.
'special' event fields
------------------------
There are a number of 'special event fields' available for use as
keys or values in a hist trigger. These look like and behave as if
they were actual event fields, but aren't really part of the event's
field definition or format file. They are however available for any
event, and can be used anywhere an actual event field could be.
They are:
common_timestamp u64 - timestamp (from ring buffer) associated
with the event, in nanoseconds. May be
modified by .usecs to have timestamps
interpreted as microseconds.
cpu int - the cpu on which the event occurred.
6.2 'hist' trigger examples
---------------------------