minix/kernel/smp.c
Tomas Hruby 5b8b623765 SMP - lazy FPU
- when a process is migrated to a different CPU it may have an active
  FPU context in the processor registers. We must save it and migrate
  it together with the process.
2010-09-15 14:11:25 +00:00

181 lines
4.1 KiB
C

#include <assert.h>
#include "smp.h"
#include "interrupt.h"
unsigned ncpus;
unsigned ht_per_core;
unsigned bsp_cpu_id;
PUBLIC struct cpu cpus[CONFIG_MAX_CPUS];
/* info passed to another cpu along with a sched ipi */
struct sched_ipi_data {
volatile u32_t flags;
volatile u32_t data;
};
PRIVATE struct sched_ipi_data sched_ipi_data[CONFIG_MAX_CPUS];
#define SCHED_IPI_STOP_PROC 1
#define SCHED_IPI_VM_INHIBIT 2
#define SCHED_IPI_SAVE_CTX 4
static volatile unsigned ap_cpus_booted;
SPINLOCK_DEFINE(big_kernel_lock)
SPINLOCK_DEFINE(boot_lock)
PUBLIC void wait_for_APs_to_finish_booting(void)
{
unsigned n = 0;
int i;
/* check how many cpus are actually alive */
for (i = 0 ; i < ncpus ; i++) {
if (cpu_test_flag(i, CPU_IS_READY))
n++;
}
if (n != ncpus)
printf("WARNING only %d out of %d cpus booted\n", n, ncpus);
/* we must let the other CPUs to run in kernel mode first */
BKL_UNLOCK();
while (ap_cpus_booted != (n - 1))
arch_pause();
/* now we have to take the lock again as we continu execution */
BKL_LOCK();
}
PUBLIC void ap_boot_finished(unsigned cpu)
{
ap_cpus_booted++;
}
PUBLIC void smp_ipi_halt_handler(void)
{
ipi_ack();
stop_local_timer();
arch_smp_halt_cpu();
}
PUBLIC void smp_schedule(unsigned cpu)
{
/*
* check if the cpu is processing some other ipi already. If yes, no
* need to wake it up
*/
if ((volatile unsigned)sched_ipi_data[cpu].flags != 0)
return;
arch_send_smp_schedule_ipi(cpu);
}
/*
* tell another cpu about a task to do and return only after the cpu acks that
* the task is finished. Also wait before it finishes task sent by another cpu
* to the same one.
*/
PRIVATE void smp_schedule_sync(struct proc * p, unsigned task)
{
unsigned cpu = p->p_cpu;
/*
* if some other cpu made a request to the same cpu, wait until it is
* done before proceeding
*/
if ((volatile unsigned)sched_ipi_data[cpu].flags != 0) {
BKL_UNLOCK();
while ((volatile unsigned)sched_ipi_data[cpu].flags != 0);
BKL_LOCK();
}
sched_ipi_data[cpu].flags |= task;
sched_ipi_data[cpu].data = (u32_t) p;
arch_send_smp_schedule_ipi(cpu);
/* wait until the destination cpu finishes its job */
BKL_UNLOCK();
while ((volatile unsigned)sched_ipi_data[cpu].flags != 0);
BKL_LOCK();
}
PUBLIC void smp_schedule_stop_proc(struct proc * p)
{
if (proc_is_runnable(p))
smp_schedule_sync(p, SCHED_IPI_STOP_PROC);
else
RTS_SET(p, RTS_PROC_STOP);
assert(RTS_ISSET(p, RTS_PROC_STOP));
}
PUBLIC void smp_schedule_vminhibit(struct proc * p)
{
if (proc_is_runnable(p))
smp_schedule_sync(p, SCHED_IPI_VM_INHIBIT);
else
RTS_SET(p, RTS_VMINHIBIT);
assert(RTS_ISSET(p, RTS_VMINHIBIT));
}
PUBLIC void smp_schedule_stop_proc_save_ctx(struct proc * p)
{
/*
* stop the processes and force the complete context of the process to
* be saved (i.e. including FPU state and such)
*/
smp_schedule_sync(p, SCHED_IPI_STOP_PROC | SCHED_IPI_SAVE_CTX);
assert(RTS_ISSET(p, RTS_PROC_STOP));
}
PUBLIC void smp_schedule_migrate_proc(struct proc * p, unsigned dest_cpu)
{
/*
* stop the processes and force the complete context of the process to
* be saved (i.e. including FPU state and such)
*/
smp_schedule_sync(p, SCHED_IPI_STOP_PROC | SCHED_IPI_SAVE_CTX);
assert(RTS_ISSET(p, RTS_PROC_STOP));
/* assign the new cpu and let the process run again */
p->p_cpu = dest_cpu;
RTS_UNSET(p, RTS_PROC_STOP);
}
PUBLIC void smp_ipi_sched_handler(void)
{
struct proc * curr;
unsigned mycpu = cpuid;
unsigned flgs;
ipi_ack();
curr = get_cpu_var(mycpu, proc_ptr);
flgs = sched_ipi_data[mycpu].flags;
if (flgs) {
struct proc * p;
p = (struct proc *)sched_ipi_data[mycpu].data;
if (flgs & SCHED_IPI_STOP_PROC) {
RTS_SET(p, RTS_PROC_STOP);
}
if (flgs & SCHED_IPI_SAVE_CTX) {
/* all context have been save already, FPU remains */
if (proc_used_fpu(p) &&
get_cpulocal_var(fpu_owner) == p) {
disable_fpu_exception();
save_local_fpu(p);
/* we re preparing to migrate somewhere else */
release_fpu(p);
}
}
if (flgs & SCHED_IPI_VM_INHIBIT) {
RTS_SET(p, RTS_VMINHIBIT);
}
}
else if (curr->p_endpoint != IDLE) {
RTS_SET(curr, RTS_PREEMPTED);
}
sched_ipi_data[cpuid].flags = 0;
}