anchor.diff:                 (when (member event (sw-events-of event-set) :key #'event-name)
                    (push (list (find-event event) total mutator gc)
                          sw-event-results))))
  -          (note :real-time real-nsec-total
  -                (- real-nsec-total real-nsec-gc) real-nsec-gc)
  -          (note :user-time user-nsec-total
  -                (- user-nsec-total user-nsec-gc) user-nsec-gc)
  -          (note :system-time system-nsec-total
  -                (- system-nsec-total system-nsec-gc) system-nsec-gc)
  +          (let ((real-nsec-mutator (- real-nsec-total real-nsec-gc))
  +                (user-nsec-mutator (- user-nsec-total user-nsec-gc)))
  +            (note :real-time real-nsec-total real-nsec-mutator real-nsec-gc)
  +            (note :user-time user-nsec-total user-nsec-mutator user-nsec-gc)
  +            (flet ((% (user real)
  +                     (cond ((zerop real) -1)
  +                           ((>= user real) 100)
  +                           (t (* 100 (/ user real))))))
  +              (note :cpu-usage
  +                    (% user-nsec-total real-nsec-total)
  +                    (% user-nsec-mutator real-nsec-mutator)
  +                    (% user-nsec-gc real-nsec-gc))))
  +          (note :system-time
  +                (* 1000 system-usec-total)
  +                (* 1000 (- system-usec-total system-usec-gc))
  +                (* 1000 system-usec-gc))
  +          (note :page-reclaims
  +                page-reclaims-total
  +                (- page-reclaims-total page-reclaims-gc)
  +                page-reclaims-gc)
  +          (note :page-faults
  +                page-faults-total
  +                (- page-faults-total page-faults-gc)
  +                page-faults-gc)
  +          (note :vcsw vcsw-total (- vcsw-total vcsw-gc) vcsw-gc)
  +          (note :ivcsw ivcsw-total (- ivcsw-total ivcsw-gc) ivcsw-gc)
             (note :gc-count gc-count -1 -1))
           (funcall consumer (nconc hw-event-results sw-event-results)))
         ;; Return FUNCTION's return values.
  
positive.code: (define-event :real-time "Real time")
  (define-event :user-time "User time")
  
  ;;;; GC runs
  
  (define-event :gc-count "GC count")
  
  ;;;; Measuring System Info
  
  (defcstruct timeval
    (sec :long)
  
negative.code:           (setq user-nsec-total (- (papi-get-virt-nsec) user-nsec-total))
            (papi-accum handle mutator-values)))
        (papi-stop handle (null-pointer))
        (multiple-value-bind (stime reclaims faults vcsw ivcsw)
            (get-resource-usage)
          (setq system-usec-total (- stime system-usec-total))
          (setq page-reclaims-total (- reclaims page-reclaims-total))
          (setq page-faults-total (- faults page-faults-total))
          (setq vcsw-total (- vcsw vcsw-total))
          (setq ivcsw-total (- ivcsw ivcsw-total)))
        ;; Aggregate measurements.
        (let ((hw-event-results
               (loop for event in (events-of event-set) and i from 0 collect
  