88c99cfbc8
be allocated as arrays indexed by the cpu id. Previously the only reliable way to know the max cpu id was through MAXCPU. mp_ncpus isn't useful here because cpu ids may be sparsely mapped, although x86 and alpha do not do this. Also, call cpu_mp_probe much earlier so the max cpu id is known before the VM starts up. This is intended to help support per cpu queues for the new allocator, but may be useful elsewhere. Reviewed by: jake Approved by: jake
319 lines
8.0 KiB
C
319 lines
8.0 KiB
C
/*
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* Copyright (c) 2001
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* John Baldwin <jhb@FreeBSD.org>. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BALDWIN AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL JOHN BALDWIN OR THE VOICES IN HIS HEAD
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* This module holds the global variables and machine independent functions
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* used for the kernel SMP support.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/ktr.h>
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#include <sys/proc.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/pcpu.h>
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#include <sys/smp.h>
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#include <sys/sysctl.h>
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volatile u_int stopped_cpus;
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volatile u_int started_cpus;
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void (*cpustop_restartfunc) __P((void));
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int mp_ncpus;
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volatile int smp_started;
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u_int all_cpus;
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u_int mp_maxid;
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SYSCTL_NODE(_kern, OID_AUTO, smp, CTLFLAG_RD, NULL, "Kernel SMP");
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int smp_active = 0; /* are the APs allowed to run? */
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SYSCTL_INT(_kern_smp, OID_AUTO, active, CTLFLAG_RW, &smp_active, 0, "");
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int smp_cpus = 1; /* how many cpu's running */
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SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD, &smp_cpus, 0, "");
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/* Enable forwarding of a signal to a process running on a different CPU */
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static int forward_signal_enabled = 1;
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SYSCTL_INT(_kern_smp, OID_AUTO, forward_signal_enabled, CTLFLAG_RW,
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&forward_signal_enabled, 0, "");
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/* Enable forwarding of roundrobin to all other cpus */
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static int forward_roundrobin_enabled = 1;
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SYSCTL_INT(_kern_smp, OID_AUTO, forward_roundrobin_enabled, CTLFLAG_RW,
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&forward_roundrobin_enabled, 0, "");
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/* Variables needed for SMP rendezvous. */
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static void (*smp_rv_setup_func)(void *arg);
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static void (*smp_rv_action_func)(void *arg);
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static void (*smp_rv_teardown_func)(void *arg);
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static void *smp_rv_func_arg;
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static volatile int smp_rv_waiters[2];
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static struct mtx smp_rv_mtx;
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static int mp_probe_status;
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/*
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* Initialize MI SMP variables.
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*/
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static void
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mp_probe(void *dummy)
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{
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mp_probe_status = cpu_mp_probe();
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}
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SYSINIT(cpu_mp_probe, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_probe, NULL);
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/*
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* Call the MD SMP initialization code.
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*/
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static void
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mp_start(void *dummy)
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{
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/* Probe for MP hardware. */
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if (mp_probe_status == 0)
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return;
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mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
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cpu_mp_start();
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printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n",
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mp_ncpus);
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cpu_mp_announce();
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}
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SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_SECOND, mp_start, NULL)
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void
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forward_signal(struct thread *td)
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{
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int id;
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/*
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* signotify() has already set PS_ASTPENDING on this process so all
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* we need to do is poke it if it is currently executing so that it
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* executes ast().
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*/
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mtx_assert(&sched_lock, MA_OWNED);
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KASSERT(td->td_proc->p_stat == SRUN, ("forward_signal: process is not SRUN"));
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CTR1(KTR_SMP, "forward_signal(%p)", td->td_proc);
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if (!smp_started || cold || panicstr)
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return;
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if (!forward_signal_enabled)
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return;
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/* No need to IPI ourself. */
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if (td == curthread)
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return;
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id = td->td_kse->ke_oncpu;
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if (id == NOCPU)
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return;
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ipi_selected(1 << id, IPI_AST);
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}
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void
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forward_roundrobin(void)
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{
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struct pcpu *pc;
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struct thread *td;
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u_int id, map;
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mtx_assert(&sched_lock, MA_OWNED);
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CTR0(KTR_SMP, "forward_roundrobin()");
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if (!smp_started || cold || panicstr)
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return;
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if (!forward_roundrobin_enabled)
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return;
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map = 0;
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SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
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td = pc->pc_curthread;
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id = pc->pc_cpumask;
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if (id != PCPU_GET(cpumask) && (id & stopped_cpus) == 0 &&
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td != pc->pc_idlethread) {
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td->td_kse->ke_flags |= KEF_NEEDRESCHED;
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map |= id;
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}
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}
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ipi_selected(map, IPI_AST);
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}
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/*
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* When called the executing CPU will send an IPI to all other CPUs
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* requesting that they halt execution.
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*
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* Usually (but not necessarily) called with 'other_cpus' as its arg.
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*
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* - Signals all CPUs in map to stop.
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* - Waits for each to stop.
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*
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* Returns:
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* -1: error
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* 0: NA
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* 1: ok
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*
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* XXX FIXME: this is not MP-safe, needs a lock to prevent multiple CPUs
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* from executing at same time.
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*/
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int
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stop_cpus(u_int map)
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{
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int i;
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if (!smp_started)
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return 0;
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CTR1(KTR_SMP, "stop_cpus(%x)", map);
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/* send the stop IPI to all CPUs in map */
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ipi_selected(map, IPI_STOP);
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i = 0;
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while ((atomic_load_acq_int(&stopped_cpus) & map) != map) {
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/* spin */
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i++;
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#ifdef DIAGNOSTIC
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if (i == 100000) {
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printf("timeout stopping cpus\n");
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break;
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}
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#endif
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}
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return 1;
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}
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/*
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* Called by a CPU to restart stopped CPUs.
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*
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* Usually (but not necessarily) called with 'stopped_cpus' as its arg.
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*
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* - Signals all CPUs in map to restart.
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* - Waits for each to restart.
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*
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* Returns:
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* -1: error
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* 0: NA
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* 1: ok
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*/
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int
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restart_cpus(u_int map)
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{
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if (!smp_started)
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return 0;
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CTR1(KTR_SMP, "restart_cpus(%x)", map);
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/* signal other cpus to restart */
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atomic_store_rel_int(&started_cpus, map);
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/* wait for each to clear its bit */
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while ((atomic_load_acq_int(&stopped_cpus) & map) != 0)
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; /* nothing */
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return 1;
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}
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/*
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* All-CPU rendezvous. CPUs are signalled, all execute the setup function
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* (if specified), rendezvous, execute the action function (if specified),
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* rendezvous again, execute the teardown function (if specified), and then
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* resume.
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*
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* Note that the supplied external functions _must_ be reentrant and aware
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* that they are running in parallel and in an unknown lock context.
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*/
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void
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smp_rendezvous_action(void)
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{
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/* setup function */
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if (smp_rv_setup_func != NULL)
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smp_rv_setup_func(smp_rv_func_arg);
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/* spin on entry rendezvous */
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atomic_add_int(&smp_rv_waiters[0], 1);
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while (atomic_load_acq_int(&smp_rv_waiters[0]) < mp_ncpus)
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; /* nothing */
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/* action function */
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if (smp_rv_action_func != NULL)
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smp_rv_action_func(smp_rv_func_arg);
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/* spin on exit rendezvous */
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atomic_add_int(&smp_rv_waiters[1], 1);
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while (atomic_load_acq_int(&smp_rv_waiters[1]) < mp_ncpus)
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; /* nothing */
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/* teardown function */
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if (smp_rv_teardown_func != NULL)
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smp_rv_teardown_func(smp_rv_func_arg);
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}
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void
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smp_rendezvous(void (* setup_func)(void *),
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void (* action_func)(void *),
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void (* teardown_func)(void *),
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void *arg)
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{
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if (!smp_started) {
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if (setup_func != NULL)
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setup_func(arg);
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if (action_func != NULL)
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action_func(arg);
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if (teardown_func != NULL)
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teardown_func(arg);
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return;
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}
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/* obtain rendezvous lock */
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mtx_lock_spin(&smp_rv_mtx);
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/* set static function pointers */
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smp_rv_setup_func = setup_func;
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smp_rv_action_func = action_func;
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smp_rv_teardown_func = teardown_func;
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smp_rv_func_arg = arg;
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smp_rv_waiters[0] = 0;
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smp_rv_waiters[1] = 0;
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/* signal other processors, which will enter the IPI with interrupts off */
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ipi_all_but_self(IPI_RENDEZVOUS);
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/* call executor function */
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smp_rendezvous_action();
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/* release lock */
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mtx_unlock_spin(&smp_rv_mtx);
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}
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