<<< value.<<< $count stores the amount returned by $count to the associated value of the corresponding execname() in the reads array. Remember, these values are stored; they are not added to the associated values of each unique key, nor are they used to replace the current associated values. In a manner of speaking, think of it as having each unique key (execname()) having multiple associated values, accumulating with each probe handler run.Note
count returns the amount of data read by the returned execname() to the virtual file system.@extractor(variable/array index expression). extractor can be any of the following integer extractors:@count(reads[execname()]) will return how many values are stored in each unique key in array reads.
@sum(reads[execname()]) will return the total of all values stored in each unique key in array reads.
Example 3.22. Multiple Array Indexes
global reads
probe vfs.read
{
reads[execname(),pid()] <<< 1
}
probe timer.s(3)
{
foreach([var1,var2] in reads)
printf("%s (%d) : %d \n", var1, var2, @count(reads[var1,var2]))
}reads. Note how the
foreach statement uses the same number of variables (that is,
var1 and var2) contained in the first instance of the array
reads from the first probe.