From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
Fix typos, inconsistencies in using quotes, incorrect section number,
etc. in the trace histogram documentation.
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
Documentation/trace/histogram.txt | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/Documentation/trace/histogram.txt b/Documentation/trace/histogram.txt
index 6e05510afc28..da955cd696f6 100644
--- a/Documentation/trace/histogram.txt
+++ b/Documentation/trace/histogram.txt
@@ -1730,35 +1730,35 @@ If a variable isn't a key variable or prefixed with 'vals=', the
associated event field will be saved in a variable but won't be summed
as a value:
- # echo 'hist:keys=next_pid:ts1=common_timestamp ... >> event/trigger
+ # echo 'hist:keys=next_pid:ts1=common_timestamp ...' >> event/trigger
Multiple variables can be assigned at the same time. The below would
result in both ts0 and b being created as variables, with both
common_timestamp and field1 additionally being summed as values:
- # echo 'hist:keys=pid:vals=$ts0,$b:ts0=common_timestamp,b=field1 ... >> \
+ # echo 'hist:keys=pid:vals=$ts0,$b:ts0=common_timestamp,b=field1 ...' >> \
event/trigger
Note that variable assignments can appear either preceding or
following their use. The command below behaves identically to the
command above:
- # echo 'hist:keys=pid:ts0=common_timestamp,b=field1:vals=$ts0,$b ... >> \
+ # echo 'hist:keys=pid:ts0=common_timestamp,b=field1:vals=$ts0,$b ...' >> \
event/trigger
Any number of variables not bound to a 'vals=' prefix can also be
assigned by simply separating them with colons. Below is the same
thing but without the values being summed in the histogram:
- # echo 'hist:keys=pid:ts0=common_timestamp:b=field1 ... >> event/trigger
+ # echo 'hist:keys=pid:ts0=common_timestamp:b=field1 ...' >> event/trigger
Variables set as above can be referenced and used in expressions on
another event.
For example, here's how a latency can be calculated:
- # echo 'hist:keys=pid,prio:ts0=common_timestamp ... >> event1/trigger
- # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp-$ts0 ... >> event2/trigger
+ # echo 'hist:keys=pid,prio:ts0=common_timestamp ...' >> event1/trigger
+ # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp-$ts0 ...' >> event2/trigger
In the first line above, the event's timetamp is saved into the
variable ts0. In the next line, ts0 is subtracted from the second
@@ -1767,7 +1767,7 @@ yet another variable, 'wakeup_lat'. The hist trigger below in turn
makes use of the wakeup_lat variable to compute a combined latency
using the same key and variable from yet another event:
- # echo 'hist:key=pid:wakeupswitch_lat=$wakeup_lat+$switchtime_lat ... >> event3/trigger
+ # echo 'hist:key=pid:wakeupswitch_lat=$wakeup_lat+$switchtime_lat ...' >> event3/trigger
2.2.2 Synthetic Events
----------------------
@@ -1808,10 +1808,11 @@ the command that defined it with a '!':
At this point, there isn't yet an actual 'wakeup_latency' event
instantiated in the event subsytem - for this to happen, a 'hist
trigger action' needs to be instantiated and bound to actual fields
-and variables defined on other events (see Section 6.3.3 below).
+and variables defined on other events (see Section 2.2.3 below on
+how that is done using hist trigger 'onmatch' action). Once that is
+done, the 'wakeup_latency' synthetic event instance is created.
-Once that is done, an event instance is created, and a histogram can
-be defined using it:
+A histogram can now be defined for the new synthetic event:
# echo 'hist:keys=pid,prio,lat.log2:sort=pid,lat' >> \
/sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger
@@ -1961,7 +1962,7 @@ hist trigger specification.
back to that pid, the timestamp difference is calculated. If the
resulting latency, stored in wakeup_lat, exceeds the current
maximum latency, the values specified in the save() fields are
- recoreded:
+ recorded:
# echo 'hist:keys=pid:ts0=common_timestamp.usecs \
if comm=="cyclictest"' >> \
--
2.18.0.rc1.242.g61856ae69a-goog
--
To unsubscribe from this list: send the line "unsubscribe linux-doc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
