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6.6.2 Cachegrind output file format

The file format is fairly straightforward, basically giving the cost centre for every line, grouped by files and functions. Total counts (e.g. total cache accesses, total L1 misses) are calculated when traversing this structure rather than during execution, to save time; the cache simulation functions are called so often that even one or two extra adds can make a sizeable difference.

The file format:

file         ::= desc_line* cmd_line events_line 
                 data_line+ summary_line
desc_line    ::= "desc:" ws? non_nl_string
cmd_line     ::= "cmd:" ws? cmd
events_line  ::= "events:" ws? (event ws)+
data_line    ::= file_line | fn_line | count_line
file_line    ::= "fl=" filename
fn_line      ::= "fn=" fn_name
count_line   ::= line_num ws? (count ws)+
summary_line ::= "summary:" ws? (count ws)+
count        ::= num | "."

Where:

• ‘non_nl_string’ is any string not containing a newline.
• ‘cmd’ is a string holding the command line of the profiled program.
• ‘event’ is a string containing no whitespace.
• ‘filename’ and ‘fn_name’ are strings.
• ‘num’ and ‘line_num’ are decimal numbers.
• ‘ws’ is whitespace.

The contents of the ‘desc:’ lines are printed out at the top of the summary. This is a generic way of providing simulation specific information, e.g. for giving the cache configuration for cache simulation.

More than one line of info can be presented for each file/fn/line number. In such cases, the counts for the named events will be accumulated.

Counts can be ‘.’ to represent zero. This makes the files easier for humans to read.

The number of counts in each ‘line’ and the ‘summary_line’ should not exceed the number of events in the ‘event_line’. If the number in each ‘line’ is less, cg_annotate treats those missing as though they were a ‘.’ entry. This saves space.

A ‘file_line’ changes the current file name. A ‘fn_line’ changes the current function name. A ‘count_line’ contains counts that pertain to the current filename/fn_name. A ‘fn=’ ‘file_line’ and a ‘fn_line’ must appear before any ‘count_line’s to give the context of the first ‘count_line’s.

Each ‘file_line’ will normally be immediately followed by a ‘fn_line’. But it doesn't have to be.