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author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-06-24 06:23:28 +0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-06-24 06:23:28 +0800 |
commit | 81f9c4e4177d31ced6f52a89bb70e93bfb77ca03 (patch) | |
tree | 2c9130e553e1321e5533a5c04a55442964390bdb /Documentation | |
parent | 5e2204832b20ef9db859dd6a2e955ac3e33eef27 (diff) | |
parent | ed7d40bc67b8353c677b38c6cdddcdc310c0f452 (diff) |
Merge tag 'trace-v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
"This contains a few fixes and a clean up.
- a bad merge caused an "endif" to go in the wrong place in
scripts/Makefile.build
- softirq tracing fix for tracing that corrupts lockdep and causes a
false splat
- histogram documentation typo fixes
- fix a bad memory reference when passing in no filter to the filter
code
- simplify code by using the swap macro instead of open coding the
swap"
* tag 'trace-v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix SKIP_STACK_VALIDATION=1 build due to bad merge with -mrecord-mcount
tracing: Fix some errors in histogram documentation
tracing: Use swap macro in update_max_tr
softirq: Reorder trace_softirqs_on to prevent lockdep splat
tracing: Check for no filter when processing event filters
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/trace/histogram.txt | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/Documentation/trace/histogram.txt b/Documentation/trace/histogram.txt index e73bcf9cb5f3..7ffea6aa22e3 100644 --- a/Documentation/trace/histogram.txt +++ b/Documentation/trace/histogram.txt @@ -1729,35 +1729,35 @@ 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 @@ -1766,7 +1766,7 @@ 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 ---------------------- @@ -1807,10 +1807,11 @@ 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 @@ -1960,7 +1961,7 @@ 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"' >> \ |