/* Like smp_idle(), this will put the core in a state that it can only be woken
* up by an IPI. For now, this is a halt. Maybe an mwait in the future.
*
* This will return if an event was pending (could be the one you were waiting
* for) or if the halt failed for some reason, such as a concurrent RKM. If
* successful, this will not return at all, and the vcore will restart from the
* top next time it wakes. Any sort of IRQ will wake the core.
*
* Alternatively, I might make this so it never returns, if that's easier to
* work with (similar issues with yield). */
void vcore_idle(void)
{
uint32_t vcoreid = vcore_id();
/* Once we enable notifs, the calling context will be treated like a uthread
* (saved into the uth slot). We don't want to ever run it again, so we
* need to make sure there's no cur_uth. */
assert(!current_uthread);
/* This clears notif_pending (check, signal, check again pattern). */
if (handle_events(vcoreid))
return;
/* This enables notifs, but also checks notif pending. At this point, any
* new notifs will restart the vcore from the top. */
enable_notifs(vcoreid);
/* From now, til we get into the kernel, any notifs will permanently destroy
* this context and start the VC from the top.
*
* Once we're in the kernel, any messages (__notify, __preempt), will be
* RKMs. halt will need to check for those atomically. Checking for
* notif_pending in the kernel (sleep only if not set) is not enough, since
* not all reasons for the kernel to stay awak set notif_pending (e.g.,
* __preempts and __death).
*
* At this point, we're out of VC ctx, so anyone who sets notif_pending
* should also send an IPI / __notify */
sys_halt_core(0);
/* in case halt returns without actually restarting the VC ctx. */
disable_notifs(vcoreid);
}
int main(int argc, char** argv)
{
uint32_t vcoreid;
int nr_vcores;
if (argc < 2)
nr_vcores = max_vcores();
else
nr_vcores = atoi(argv[1]);
/* Inits a thread for us, though we won't use it. Just a hack to get into
* _M mode. Note this requests one vcore for us */
struct uthread dummy = {0};
uthread_2ls_init(&dummy, &ghetto_sched_ops);
uthread_mcp_init();
/* Reset the blockon to be the spinner... This is really shitty. Any
* blocking calls after we become an MCP and before this will fail. This is
* just mhello showing its warts due to trying to work outside uthread.c */
ros_syscall_blockon = __ros_syscall_spinon;
vcore_request(nr_vcores - 1); /* since we already have 1 */
while (1)
sys_halt_core(0);
return 0;
}
void ghetto_vcore_entry(void)
{
if (vcore_id() == 0)
run_current_uthread();
while (1)
sys_halt_core(0);
}
/* This will keep a core from spinning forever, but will also allow it to still
* schedule() and run _S processes. arg1 is the number of loops (0 for
* forever), and arg2 is how many usec to wait per loop. */
int main(int argc, char** argv)
{
unsigned long nr_loops = 1; /* default, 1 loop */
unsigned long timeout = 5000000; /* default, 5 sec */
int i = 0;
if (argc > 1)
nr_loops = strtol(argv[1], 0, 10);
if (argc > 2)
timeout = strtol(argv[2], 0, 10);
printf("Idling for %d usec for %d loops\n", timeout, nr_loops);
while (!nr_loops || i++ < nr_loops) {
sys_halt_core(timeout);
sys_yield(0);
}
return 0;
}