Hi Tom, On Mon, Jun 26, 2017 at 05:49:17PM -0500, Tom Zanussi wrote: > Add support for saving the value of a current event's event field by > assigning it to a variable that can be read by a subsequent event. > > The basic syntax for saving a variable is to simply prefix a unique > variable name not corresponding to any keyword along with an '=' sign > to any event field. > > Both keys and values can be saved and retrieved in this way: > > # echo 'hist:keys=next_pid:vals=ts0=common_timestamp ... > # echo 'hist:key=timer_pid=common_pid ...' > > 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:... > > Multiple variables can be assigned at the same time: > > # echo 'hist:keys=pid:vals=ts0=common_timestamp,b=field1,field2 ... > > Multiple (or single) variables can also be assigned at the same time > using separate assignments: > > # echo 'hist:keys=pid:vals=ts0=common_timestamp:b=field1:c=field2 ... It seems the variable definition can be hard to read if multiple variables with expression are used. I think it'd be better to make it clear what's the key and the values by separating the variable definition. For example, the above example can be written as # echo 'hist:key=pid:val=ts0:ts0=$common_timestamp:b=field1:...' I know this is not a good example since the 'ts0' is a simple reference to the timestamp but it can be more complex.. What do you think? Thanks, Namhyung > > Variables set as above can be used by being referenced from another > event, as described in a subsequent patch. > > Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
