shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-06 10:58:48 +09:00
Code Issues Packages Projects Releases Wiki Activity

UPSTREAM: tracing/histogram: Document expression arithmetic and constants

Browse Source 
Histogram expressions now support division, and multiplication in
addition to the already supported subtraction and addition operators.

Numeric constants can also be used in a hist trigger expressions
or assigned to a variable and used by refernce in an expression.

Link: https://lkml.kernel.org/r/20211025200852.3002369-9-kaleshsingh@google.com

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
(cherry picked from commit 2d2f6d4b8c)

Bug: 146055070
Bug: 145972256
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Change-Id: Iaf9609e3b0373414280f6c8aae638c034797bbf2
This commit is contained in:
Kalesh Singh
2021-10-25 13:08:40 -07:00
parent d3214e5dc9
commit 9beacd375b
1 changed files with 14 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
Documentation/trace/histogram.rst
View File

@@ -1763,6 +1763,20 @@ using the same key and variable from yet another event::
# echo 'hist:key=pid:wakeupswitch_lat=$wakeup_lat+$switchtime_lat ...' >> event3/trigger
Expressions support the use of addition, subtraction, multiplication and
division operators (+-*/).
Note that division by zero always returns -1.
Numeric constants can also be used directly in an expression::
# echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/1000000 ...' >> event/trigger
or assigned to a variable and referenced in a subsequent expression::
# echo 'hist:keys=next_pid:us_per_sec=1000000 ...' >> event/trigger
# echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/$us_per_sec ...' >> event/trigger
2.2.2 Synthetic Events
----------------------