freebsd-dev/sys/kern/subr_smp.c
John Birrell 833b4a131a Allow a rendezvous with just a specified CPU too.
Make the API work in the non-smp case too so that a kernel module
can work the same regardless of whether or not it is loaded on a SMP
kernel or not.
2008-05-23 04:05:26 +00:00

640 lines
16 KiB
C

/*-
* Copyright (c) 2001
* John Baldwin <jhb@FreeBSD.org>. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BALDWIN AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL JOHN BALDWIN OR THE VOICES IN HIS HEAD
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This module holds the global variables and machine independent functions
* used for the kernel SMP support.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/proc.h>
#include <sys/bus.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/pcpu.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <machine/cpu.h>
#include <machine/smp.h>
#include "opt_sched.h"
#ifdef SMP
volatile cpumask_t stopped_cpus;
volatile cpumask_t started_cpus;
cpumask_t idle_cpus_mask;
cpumask_t hlt_cpus_mask;
cpumask_t logical_cpus_mask;
void (*cpustop_restartfunc)(void);
#endif
/* This is used in modules that need to work in both SMP and UP. */
cpumask_t all_cpus;
int mp_ncpus;
/* export this for libkvm consumers. */
int mp_maxcpus = MAXCPU;
volatile int smp_started;
u_int mp_maxid;
SYSCTL_NODE(_kern, OID_AUTO, smp, CTLFLAG_RD, NULL, "Kernel SMP");
SYSCTL_INT(_kern_smp, OID_AUTO, maxid, CTLFLAG_RD, &mp_maxid, 0,
"Max CPU ID.");
SYSCTL_INT(_kern_smp, OID_AUTO, maxcpus, CTLFLAG_RD, &mp_maxcpus, 0,
"Max number of CPUs that the system was compiled for.");
int smp_active = 0; /* are the APs allowed to run? */
SYSCTL_INT(_kern_smp, OID_AUTO, active, CTLFLAG_RW, &smp_active, 0,
"Number of Auxillary Processors (APs) that were successfully started");
int smp_disabled = 0; /* has smp been disabled? */
SYSCTL_INT(_kern_smp, OID_AUTO, disabled, CTLFLAG_RDTUN, &smp_disabled, 0,
"SMP has been disabled from the loader");
TUNABLE_INT("kern.smp.disabled", &smp_disabled);
int smp_cpus = 1; /* how many cpu's running */
SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD, &smp_cpus, 0,
"Number of CPUs online");
int smp_topology = 0; /* Which topology we're using. */
SYSCTL_INT(_kern_smp, OID_AUTO, topology, CTLFLAG_RD, &smp_topology, 0,
"Topology override setting; 0 is default provided by hardware.");
TUNABLE_INT("kern.smp.topology", &smp_topology);
#ifdef SMP
/* Enable forwarding of a signal to a process running on a different CPU */
static int forward_signal_enabled = 1;
SYSCTL_INT(_kern_smp, OID_AUTO, forward_signal_enabled, CTLFLAG_RW,
&forward_signal_enabled, 0,
"Forwarding of a signal to a process on a different CPU");
/* Enable forwarding of roundrobin to all other cpus */
static int forward_roundrobin_enabled = 1;
SYSCTL_INT(_kern_smp, OID_AUTO, forward_roundrobin_enabled, CTLFLAG_RW,
&forward_roundrobin_enabled, 0,
"Forwarding of roundrobin to all other CPUs");
/* Variables needed for SMP rendezvous. */
static volatile cpumask_t smp_rv_cpumask;
static void (*volatile smp_rv_setup_func)(void *arg);
static void (*volatile smp_rv_action_func)(void *arg);
static void (*volatile smp_rv_teardown_func)(void *arg);
static void * volatile smp_rv_func_arg;
static volatile int smp_rv_waiters[3];
/*
* Shared mutex to restrict busywaits between smp_rendezvous() and
* smp(_targeted)_tlb_shootdown(). A deadlock occurs if both of these
* functions trigger at once and cause multiple CPUs to busywait with
* interrupts disabled.
*/
struct mtx smp_ipi_mtx;
/*
* Let the MD SMP code initialize mp_maxid very early if it can.
*/
static void
mp_setmaxid(void *dummy)
{
cpu_mp_setmaxid();
}
SYSINIT(cpu_mp_setmaxid, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setmaxid, NULL);
/*
* Call the MD SMP initialization code.
*/
static void
mp_start(void *dummy)
{
/* Probe for MP hardware. */
if (smp_disabled != 0 || cpu_mp_probe() == 0) {
mp_ncpus = 1;
all_cpus = PCPU_GET(cpumask);
return;
}
mtx_init(&smp_ipi_mtx, "smp rendezvous", NULL, MTX_SPIN);
cpu_mp_start();
printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n",
mp_ncpus);
cpu_mp_announce();
}
SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_THIRD, mp_start, NULL);
void
forward_signal(struct thread *td)
{
int id;
/*
* signotify() has already set TDF_ASTPENDING and TDF_NEEDSIGCHECK on
* this thread, so all we need to do is poke it if it is currently
* executing so that it executes ast().
*/
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT(TD_IS_RUNNING(td),
("forward_signal: thread is not TDS_RUNNING"));
CTR1(KTR_SMP, "forward_signal(%p)", td->td_proc);
if (!smp_started || cold || panicstr)
return;
if (!forward_signal_enabled)
return;
/* No need to IPI ourself. */
if (td == curthread)
return;
id = td->td_oncpu;
if (id == NOCPU)
return;
ipi_selected(1 << id, IPI_AST);
}
void
forward_roundrobin(void)
{
struct pcpu *pc;
struct thread *td;
cpumask_t id, map, me;
CTR0(KTR_SMP, "forward_roundrobin()");
if (!smp_started || cold || panicstr)
return;
if (!forward_roundrobin_enabled)
return;
map = 0;
me = PCPU_GET(cpumask);
SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
td = pc->pc_curthread;
id = pc->pc_cpumask;
if (id != me && (id & stopped_cpus) == 0 &&
!TD_IS_IDLETHREAD(td)) {
td->td_flags |= TDF_NEEDRESCHED;
map |= id;
}
}
ipi_selected(map, IPI_AST);
}
/*
* When called the executing CPU will send an IPI to all other CPUs
* requesting that they halt execution.
*
* Usually (but not necessarily) called with 'other_cpus' as its arg.
*
* - Signals all CPUs in map to stop.
* - Waits for each to stop.
*
* Returns:
* -1: error
* 0: NA
* 1: ok
*
* XXX FIXME: this is not MP-safe, needs a lock to prevent multiple CPUs
* from executing at same time.
*/
int
stop_cpus(cpumask_t map)
{
int i;
if (!smp_started)
return 0;
CTR1(KTR_SMP, "stop_cpus(%x)", map);
/* send the stop IPI to all CPUs in map */
ipi_selected(map, IPI_STOP);
i = 0;
while ((stopped_cpus & map) != map) {
/* spin */
cpu_spinwait();
i++;
#ifdef DIAGNOSTIC
if (i == 100000) {
printf("timeout stopping cpus\n");
break;
}
#endif
}
return 1;
}
/*
* Called by a CPU to restart stopped CPUs.
*
* Usually (but not necessarily) called with 'stopped_cpus' as its arg.
*
* - Signals all CPUs in map to restart.
* - Waits for each to restart.
*
* Returns:
* -1: error
* 0: NA
* 1: ok
*/
int
restart_cpus(cpumask_t map)
{
if (!smp_started)
return 0;
CTR1(KTR_SMP, "restart_cpus(%x)", map);
/* signal other cpus to restart */
atomic_store_rel_int(&started_cpus, map);
/* wait for each to clear its bit */
while ((stopped_cpus & map) != 0)
cpu_spinwait();
return 1;
}
/*
* All-CPU rendezvous. CPUs are signalled, all execute the setup function
* (if specified), rendezvous, execute the action function (if specified),
* rendezvous again, execute the teardown function (if specified), and then
* resume.
*
* Note that the supplied external functions _must_ be reentrant and aware
* that they are running in parallel and in an unknown lock context.
*/
void
smp_rendezvous_action(void)
{
cpumask_t map = smp_rv_cpumask;
int i, ncpus = 0;
void* local_func_arg = smp_rv_func_arg;
void (*local_setup_func)(void*) = smp_rv_setup_func;
void (*local_action_func)(void*) = smp_rv_action_func;
void (*local_teardown_func)(void*) = smp_rv_teardown_func;
for (i = 0; i < MAXCPU; i++)
if (((1 << i) & map) != 0 && pcpu_find(i) != NULL)
ncpus++;
/* Ensure we have up-to-date values. */
atomic_add_acq_int(&smp_rv_waiters[0], 1);
while (smp_rv_waiters[0] < ncpus)
cpu_spinwait();
/* setup function */
if (local_setup_func != smp_no_rendevous_barrier) {
if (smp_rv_setup_func != NULL)
smp_rv_setup_func(smp_rv_func_arg);
/* spin on entry rendezvous */
atomic_add_int(&smp_rv_waiters[1], 1);
while (smp_rv_waiters[1] < ncpus)
cpu_spinwait();
}
/* action function */
if (local_action_func != NULL)
local_action_func(local_func_arg);
/* spin on exit rendezvous */
atomic_add_int(&smp_rv_waiters[2], 1);
if (local_teardown_func == smp_no_rendevous_barrier)
return;
while (smp_rv_waiters[2] < ncpus)
cpu_spinwait();
/* teardown function */
if (local_teardown_func != NULL)
local_teardown_func(local_func_arg);
}
void
smp_rendezvous_cpus(cpumask_t map,
void (* setup_func)(void *),
void (* action_func)(void *),
void (* teardown_func)(void *),
void *arg)
{
int i, ncpus = 0;
if (!smp_started) {
if (setup_func != NULL)
setup_func(arg);
if (action_func != NULL)
action_func(arg);
if (teardown_func != NULL)
teardown_func(arg);
return;
}
for (i = 0; i < MAXCPU; i++)
if (((1 << i) & map) != 0 && pcpu_find(i) != NULL)
ncpus++;
/* obtain rendezvous lock */
mtx_lock_spin(&smp_ipi_mtx);
/* set static function pointers */
smp_rv_cpumask = map;
smp_rv_setup_func = setup_func;
smp_rv_action_func = action_func;
smp_rv_teardown_func = teardown_func;
smp_rv_func_arg = arg;
smp_rv_waiters[1] = 0;
smp_rv_waiters[2] = 0;
atomic_store_rel_int(&smp_rv_waiters[0], 0);
/* signal other processors, which will enter the IPI with interrupts off */
ipi_selected(map & ~(1 << curcpu), IPI_RENDEZVOUS);
/* Check if the current CPU is in the map */
if ((map & (1 << curcpu)) != 0)
smp_rendezvous_action();
if (teardown_func == smp_no_rendevous_barrier)
while (atomic_load_acq_int(&smp_rv_waiters[2]) < ncpus)
cpu_spinwait();
/* release lock */
mtx_unlock_spin(&smp_ipi_mtx);
}
void
smp_rendezvous(void (* setup_func)(void *),
void (* action_func)(void *),
void (* teardown_func)(void *),
void *arg)
{
smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, arg);
}
static struct cpu_group group[MAXCPU];
struct cpu_group *
smp_topo(void)
{
struct cpu_group *top;
/*
* Check for a fake topology request for debugging purposes.
*/
switch (smp_topology) {
case 1:
/* Dual core with no sharing. */
top = smp_topo_1level(CG_SHARE_NONE, 2, 0);
break;
case 2:
/* No topology, all cpus are equal. */
top = smp_topo_none();
break;
case 3:
/* Dual core with shared L2. */
top = smp_topo_1level(CG_SHARE_L2, 2, 0);
break;
case 4:
/* quad core, shared l3 among each package, private l2. */
top = smp_topo_1level(CG_SHARE_L3, 4, 0);
break;
case 5:
/* quad core, 2 dualcore parts on each package share l2. */
top = smp_topo_2level(CG_SHARE_NONE, 2, CG_SHARE_L2, 2, 0);
break;
case 6:
/* Single-core 2xHTT */
top = smp_topo_1level(CG_SHARE_L1, 2, CG_FLAG_HTT);
break;
case 7:
/* quad core with a shared l3, 8 threads sharing L2. */
top = smp_topo_2level(CG_SHARE_L3, 4, CG_SHARE_L2, 8,
CG_FLAG_THREAD);
break;
default:
/* Default, ask the system what it wants. */
top = cpu_topo();
break;
}
/*
* Verify the returned topology.
*/
if (top->cg_count != mp_ncpus)
panic("Built bad topology at %p. CPU count %d != %d",
top, top->cg_count, mp_ncpus);
if (top->cg_mask != all_cpus)
panic("Built bad topology at %p. CPU mask 0x%X != 0x%X",
top, top->cg_mask, all_cpus);
return (top);
}
struct cpu_group *
smp_topo_none(void)
{
struct cpu_group *top;
top = &group[0];
top->cg_parent = NULL;
top->cg_child = NULL;
top->cg_mask = (1 << mp_ncpus) - 1;
top->cg_count = mp_ncpus;
top->cg_children = 0;
top->cg_level = CG_SHARE_NONE;
top->cg_flags = 0;
return (top);
}
static int
smp_topo_addleaf(struct cpu_group *parent, struct cpu_group *child, int share,
int count, int flags, int start)
{
cpumask_t mask;
int i;
for (mask = 0, i = 0; i < count; i++, start++)
mask |= (1 << start);
child->cg_parent = parent;
child->cg_child = NULL;
child->cg_children = 0;
child->cg_level = share;
child->cg_count = count;
child->cg_flags = flags;
child->cg_mask = mask;
parent->cg_children++;
for (; parent != NULL; parent = parent->cg_parent) {
if ((parent->cg_mask & child->cg_mask) != 0)
panic("Duplicate children in %p. mask 0x%X child 0x%X",
parent, parent->cg_mask, child->cg_mask);
parent->cg_mask |= child->cg_mask;
parent->cg_count += child->cg_count;
}
return (start);
}
struct cpu_group *
smp_topo_1level(int share, int count, int flags)
{
struct cpu_group *child;
struct cpu_group *top;
int packages;
int cpu;
int i;
cpu = 0;
top = &group[0];
packages = mp_ncpus / count;
top->cg_child = child = &group[1];
top->cg_level = CG_SHARE_NONE;
for (i = 0; i < packages; i++, child++)
cpu = smp_topo_addleaf(top, child, share, count, flags, cpu);
return (top);
}
struct cpu_group *
smp_topo_2level(int l2share, int l2count, int l1share, int l1count,
int l1flags)
{
struct cpu_group *top;
struct cpu_group *l1g;
struct cpu_group *l2g;
int cpu;
int i;
int j;
cpu = 0;
top = &group[0];
l2g = &group[1];
top->cg_child = l2g;
top->cg_level = CG_SHARE_NONE;
top->cg_children = mp_ncpus / (l2count * l1count);
l1g = l2g + top->cg_children;
for (i = 0; i < top->cg_children; i++, l2g++) {
l2g->cg_parent = top;
l2g->cg_child = l1g;
l2g->cg_level = l2share;
for (j = 0; j < l2count; j++, l1g++)
cpu = smp_topo_addleaf(l2g, l1g, l1share, l1count,
l1flags, cpu);
}
return (top);
}
struct cpu_group *
smp_topo_find(struct cpu_group *top, int cpu)
{
struct cpu_group *cg;
cpumask_t mask;
int children;
int i;
mask = (1 << cpu);
cg = top;
for (;;) {
if ((cg->cg_mask & mask) == 0)
return (NULL);
if (cg->cg_children == 0)
return (cg);
children = cg->cg_children;
for (i = 0, cg = cg->cg_child; i < children; cg++, i++)
if ((cg->cg_mask & mask) != 0)
break;
}
return (NULL);
}
#else /* !SMP */
void
smp_rendezvous_cpus(cpumask_t map,
void (*setup_func)(void *),
void (*action_func)(void *),
void (*teardown_func)(void *),
void *arg)
{
if (setup_func != NULL)
setup_func(arg);
if (action_func != NULL)
action_func(arg);
if (teardown_func != NULL)
teardown_func(arg);
}
void
smp_rendezvous(void (*setup_func)(void *),
void (*action_func)(void *),
void (*teardown_func)(void *),
void *arg)
{
if (setup_func != NULL)
setup_func(arg);
if (action_func != NULL)
action_func(arg);
if (teardown_func != NULL)
teardown_func(arg);
}
/*
* Provide dummy SMP support for UP kernels. Modules that need to use SMP
* APIs will still work using this dummy support.
*/
static void
mp_setvariables_for_up(void *dummy)
{
mp_ncpus = 1;
mp_maxid = PCPU_GET(cpuid);
all_cpus = PCPU_GET(cpumask);
KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero"));
}
SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST,
mp_setvariables_for_up, NULL);
#endif /* SMP */
void
smp_no_rendevous_barrier(void *dummy)
{
#ifdef SMP
KASSERT((!smp_started),("smp_no_rendevous called and smp is started"));
#endif
}