Hi util-linux maintainers,
the following was reported to Debian, regarding the hardlink
utility. It appears to be an upstream issue. Maybe someone can look
at it. CC:ing наб who seems to have touched the relevant function
last.
Thanks,
Chris
* Marc Lehmann <[email protected]> [260708 07:23]:
Version: 2.41-5
Dear Maintainer,
while strace'ing to find out why hardlink is so slow, IO found it does this
sequence between every fstatat call:
gettid() = 36482
getpid() = 36482
tgkill(36482, 36482, 0) = 0
this seems to be a pretty weird thing to do in a tighht scanning
loop. Looking at the code, handle_interrupt is responsible:
/**
* handle_interrupt - Handle a signal
*/
static void handle_interrupt(void)
{
switch (last_signal) {
case SIGUSR1:
print_stats();
putchar('\n');
break;
default:
signal(last_signal, SIG_DFL);
raise(last_signal);
break;
}
last_signal = 0;
}
this is already a weird function to begin with, but crucially, it calls
signal(0,... and raise(0).
it seems to me the former is likely undefined behaviour and the latter is
just unnecessartily slow.
most likely, handle_interrupt simply should not be called after every fstatat,
or at all, without last_signal bering set beforehand.
