https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97834
--- Comment #6 from Martin Liška <marxin at gcc dot gnu.org> --- (In reply to Roland Illig from comment #0) > Since 2003-05-14, gcov_open calls setbuf (gcov_var.file, (char *)0), thereby > slowing down the instrumentation a lot. > Can you please explain what's slow? Is it dumping of gcda files that happen in an instrumented binary. Or loading of profiles which happens in the GCC compiler? Second note: doing strace on Linux on the instrumented binary I see: openat(AT_FDCWD, "/home/marxin/Programming/testcases/a.gcda", O_RDWR|O_CREAT, 0666) = 3 read(3, "adcge01B\260\311\243\321\0\0\0\241\2\0\0\0\2\0\0\0\2\0\0\0\0\0\0\1\3\0\0\0\353rp\6*|:\323\350\351]\333\0\0\241\1\2\0\0\0\2\0\0\0\0\0\0\0\0\0\257\1\2\0\0\0\1\0\0\0\0\0\0\0\0\0\0\0", 4096) = 84 read(3, "", 4012) = 0
