On Thu, 14 Jun 2018 15:48:59 -0700 Joel Fernandes <joelaf@xxxxxxxxxx> wrote: > From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx> > > Fix typos, inconsistencies in using quotes, incorrect section number, > etc. in the trace histogram documentation. Looks good to me. Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Thanks! > > 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 > -- Masami Hiramatsu <mhiramat@xxxxxxxxxx> -- 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
