My gsoc task is to speed up calendar part of e-d-s. These days I have been using  evo calendar extensively. My aim was to identify the most serious bottlenecks by sysprof.

Here are the results of my 5 minute session. The tests were carried out on big calendars, which I received from Federico.

Sysprof analysis of evolution data server

Several things should be noticed:

  • Almost all system time is divided between Evo and Firefox
  • About 30% of system time was spent in Evolution, 15% in e-d-s.
  • I was using only file backend (e-d-s time was spent in e_cal_backend_file_start_query 14%)


  • Almost all e-d-s time was spent in e_cal_backend_start_query – 14%. This method is called by e-d-s clients (Evolution, clocks…) and does complete sweep  through the calendar. Clients want to get back calendar objects filtered by some expression (sexp).
  • For every calendar object, test against the expression is carried out (e_cal_backend_sexp_match_comp – 11%),  generating all recurrences.  Usually, the evaluation of expression leads to test, if event occurs in some time range (func_occur_in_time_range – 6%). The second very often used function seems to be  e_cal_backend_sexp_func_make_time – 3.9%. Both  these functions sooner or later call function icaltime_as_timet_with_zone, in which is spent 3.60% and 3.13% – summing up to about 6.7% of system time. In fact, these functions are usually called together, because the typical test is “occur-in-time-range? (make-time \”ISO_DATE_STR\”) (make-time \”ISO_DATE_STR\”)”. The expression  make-time “ISO_DATE_STR” leads to calling e_cal_backend_sexp_func_make_time, which converts date from iso string to time_t value. Expression occur-in-time-range leads to calling func_occur_in_time_range.
  • When constructing expression “occur-in-time-range? (make-time \”ISO_DATE_STR\”) (make-time \”ISO_DATE_STR\”)”, time_t value is converted to the string. Later, when evaluating expression, string is converted to time_t (by make-time).

Time spent in converting time formatsTime spent in converting time formats


  • In e-d-s we spent about 15% of system time, and almost 7% was spent in icaltime_as_timet_with_zone. The function is called to find out, if calendar event occurs in some time range.  There is a lot of time conversion from time_t to string and back.  The rest was spent by sweeping through the calendar objects and generating recurrences.