count: substract overhead per call

* count.c (zero_ts): New variable.
(count_syscall): Calculate the spent time in the wts variable, then add
it to cc->time.
(call_summary_pers): Do not perform overhead correction.

diff --git a/count.c b/count.c
index 298cb6815e88bd5f69e231f5738b0abcaa5687f3..e66b85e530322535a6d2cfae99cc92be838e78d2 100644 (file)
--- a/count.c
+++ b/count.c
@@ -26,6 +26,8 @@ struct call_counts {
 static struct call_counts *countv[SUPPORTED_PERSONALITIES];
 #define counts (countv[current_personality])
 
+static const struct timespec zero_ts;
+
 static struct timespec overhead;
 
 void
@@ -42,16 +44,17 @@ count_syscall(struct tcb *tcp, const struct timespec *syscall_exiting_ts)
        if (syserror(tcp))
                cc->errors++;
 
+       struct timespec wts;
        if (count_wallclock) {
                /* wall clock time spent while in syscall */
-               struct timespec wts;
                ts_sub(&wts, syscall_exiting_ts, &tcp->etime);
-
-               ts_add(&cc->time, &cc->time, &wts);
+               ts_sub(&wts, &wts, &overhead);
        } else {
                /* system CPU time spent while in syscall */
-               ts_add(&cc->time, &cc->time, &tcp->dtime);
+               ts_sub(&wts, &tcp->dtime, &overhead);
        }
+
+       ts_add(&cc->time, &cc->time, ts_max(&wts, &zero_ts));
 }
 
 static int
@@ -133,10 +136,6 @@ call_summary_pers(FILE *outf)
                sorted_count[i] = i;
                if (counts == NULL || counts[i].calls == 0)
                        continue;
-               ts_mul(&dtv, &overhead, counts[i].calls);
-               ts_sub(&counts[i].time, &counts[i].time, &dtv);
-               if (counts[i].time.tv_sec < 0 || counts[i].time.tv_nsec < 0)
-                       counts[i].time.tv_sec = counts[i].time.tv_nsec = 0;
                call_cum += counts[i].calls;
                error_cum += counts[i].errors;
                ts_add(&tv_cum, &tv_cum, &counts[i].time);