486a941418
a thread is an idle thread, just see if it has the IDLETD flag set. That flag will probably move to the pflags word as it's permenent and never chenges for the life of the system so it doesn't need locking.
390 lines
10 KiB
C
390 lines
10 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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/*
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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/cdefs.h>
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__FBSDID("$FreeBSD$");
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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/bus.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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#include <machine/smp.h>
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#include "opt_sched.h"
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#ifdef SMP
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volatile cpumask_t stopped_cpus;
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volatile cpumask_t started_cpus;
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cpumask_t idle_cpus_mask;
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cpumask_t hlt_cpus_mask;
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cpumask_t logical_cpus_mask;
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void (*cpustop_restartfunc)(void);
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#endif
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/* This is used in modules that need to work in both SMP and UP. */
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cpumask_t all_cpus;
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int mp_ncpus;
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/* export this for libkvm consumers. */
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int mp_maxcpus = MAXCPU;
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struct cpu_top *smp_topology;
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volatile int smp_started;
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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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SYSCTL_INT(_kern_smp, OID_AUTO, maxcpus, CTLFLAG_RD, &mp_maxcpus, 0,
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"Max number of CPUs that the system was compiled for.");
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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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"Number of Auxillary Processors (APs) that were successfully started");
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int smp_disabled = 0; /* has smp been disabled? */
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SYSCTL_INT(_kern_smp, OID_AUTO, disabled, CTLFLAG_RDTUN, &smp_disabled, 0,
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"SMP has been disabled from the loader");
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TUNABLE_INT("kern.smp.disabled", &smp_disabled);
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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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"Number of CPUs online");
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#ifdef SMP
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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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"Forwarding of a signal to a process on a different CPU");
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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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"Forwarding of roundrobin to all other CPUs");
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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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/*
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* Shared mutex to restrict busywaits between smp_rendezvous() and
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* smp(_targeted)_tlb_shootdown(). A deadlock occurs if both of these
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* functions trigger at once and cause multiple CPUs to busywait with
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* interrupts disabled.
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*/
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struct mtx smp_ipi_mtx;
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/*
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* Let the MD SMP code initialize mp_maxid very early if it can.
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*/
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static void
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mp_setmaxid(void *dummy)
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{
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cpu_mp_setmaxid();
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}
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SYSINIT(cpu_mp_setmaxid, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setmaxid, 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 (smp_disabled != 0 || cpu_mp_probe() == 0) {
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mp_ncpus = 1;
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all_cpus = PCPU_GET(cpumask);
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return;
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}
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mtx_init(&smp_ipi_mtx, "smp rendezvous", NULL, 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 TDF_ASTPENDING and TDF_NEEDSIGCHECK on
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* this thread, so all we need to do is poke it if it is currently
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* executing so that it executes ast().
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*/
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mtx_assert(&sched_lock, MA_OWNED);
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KASSERT(TD_IS_RUNNING(td),
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("forward_signal: thread is not TDS_RUNNING"));
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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_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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cpumask_t id, map, me;
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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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me = PCPU_GET(cpumask);
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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 != me && (id & stopped_cpus) == 0 &&
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!TD_IS_IDLETHREAD(td)) {
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td->td_flags |= TDF_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(cpumask_t 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(cpumask_t 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_ipi_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_ipi_mtx);
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}
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#else /* !SMP */
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/*
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* Provide dummy SMP support for UP kernels. Modules that need to use SMP
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* APIs will still work using this dummy support.
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*/
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static void
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mp_setvariables_for_up(void *dummy)
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{
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mp_ncpus = 1;
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mp_maxid = PCPU_GET(cpuid);
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all_cpus = PCPU_GET(cpumask);
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KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero"));
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}
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SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST,
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mp_setvariables_for_up, NULL)
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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 (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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}
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#endif /* SMP */
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