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1022 lines
26 KiB
C
1022 lines
26 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2018, Matthew Macy <mmacy@freebsd.org>
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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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/counter.h>
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#include <sys/epoch.h>
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#include <sys/gtaskqueue.h>
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#include <sys/kernel.h>
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#include <sys/limits.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/pcpu.h>
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#include <sys/proc.h>
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#include <sys/sched.h>
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#include <sys/sx.h>
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#include <sys/smp.h>
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#include <sys/sysctl.h>
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#include <sys/turnstile.h>
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#ifdef EPOCH_TRACE
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#include <machine/stdarg.h>
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#include <sys/stack.h>
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#include <sys/tree.h>
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#endif
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#include <vm/vm.h>
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#include <vm/vm_extern.h>
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#include <vm/vm_kern.h>
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#include <vm/uma.h>
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#include <ck_epoch.h>
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#ifdef __amd64__
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#define EPOCH_ALIGN CACHE_LINE_SIZE*2
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#else
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#define EPOCH_ALIGN CACHE_LINE_SIZE
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#endif
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TAILQ_HEAD (epoch_tdlist, epoch_tracker);
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typedef struct epoch_record {
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ck_epoch_record_t er_record;
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struct epoch_context er_drain_ctx;
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struct epoch *er_parent;
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volatile struct epoch_tdlist er_tdlist;
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volatile uint32_t er_gen;
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uint32_t er_cpuid;
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#ifdef INVARIANTS
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/* Used to verify record ownership for non-preemptible epochs. */
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struct thread *er_td;
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#endif
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} __aligned(EPOCH_ALIGN) *epoch_record_t;
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struct epoch {
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struct ck_epoch e_epoch __aligned(EPOCH_ALIGN);
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epoch_record_t e_pcpu_record;
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int e_in_use;
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int e_flags;
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struct sx e_drain_sx;
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struct mtx e_drain_mtx;
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volatile int e_drain_count;
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const char *e_name;
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};
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/* arbitrary --- needs benchmarking */
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#define MAX_ADAPTIVE_SPIN 100
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#define MAX_EPOCHS 64
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CTASSERT(sizeof(ck_epoch_entry_t) == sizeof(struct epoch_context));
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SYSCTL_NODE(_kern, OID_AUTO, epoch, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
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"epoch information");
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SYSCTL_NODE(_kern_epoch, OID_AUTO, stats, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
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"epoch stats");
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/* Stats. */
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static counter_u64_t block_count;
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SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, nblocked, CTLFLAG_RW,
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&block_count, "# of times a thread was in an epoch when epoch_wait was called");
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static counter_u64_t migrate_count;
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SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, migrations, CTLFLAG_RW,
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&migrate_count, "# of times thread was migrated to another CPU in epoch_wait");
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static counter_u64_t turnstile_count;
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SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, ncontended, CTLFLAG_RW,
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&turnstile_count, "# of times a thread was blocked on a lock in an epoch during an epoch_wait");
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static counter_u64_t switch_count;
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SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, switches, CTLFLAG_RW,
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&switch_count, "# of times a thread voluntarily context switched in epoch_wait");
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static counter_u64_t epoch_call_count;
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SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, epoch_calls, CTLFLAG_RW,
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&epoch_call_count, "# of times a callback was deferred");
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static counter_u64_t epoch_call_task_count;
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SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, epoch_call_tasks, CTLFLAG_RW,
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&epoch_call_task_count, "# of times a callback task was run");
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TAILQ_HEAD (threadlist, thread);
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CK_STACK_CONTAINER(struct ck_epoch_entry, stack_entry,
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ck_epoch_entry_container)
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static struct epoch epoch_array[MAX_EPOCHS];
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DPCPU_DEFINE(struct grouptask, epoch_cb_task);
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DPCPU_DEFINE(int, epoch_cb_count);
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static __read_mostly int inited;
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__read_mostly epoch_t global_epoch;
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__read_mostly epoch_t global_epoch_preempt;
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static void epoch_call_task(void *context __unused);
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static uma_zone_t pcpu_zone_record;
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static struct sx epoch_sx;
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#define EPOCH_LOCK() sx_xlock(&epoch_sx)
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#define EPOCH_UNLOCK() sx_xunlock(&epoch_sx)
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static epoch_record_t
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epoch_currecord(epoch_t epoch)
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{
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return (zpcpu_get(epoch->e_pcpu_record));
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}
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#ifdef EPOCH_TRACE
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struct stackentry {
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RB_ENTRY(stackentry) se_node;
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struct stack se_stack;
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};
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static int
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stackentry_compare(struct stackentry *a, struct stackentry *b)
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{
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if (a->se_stack.depth > b->se_stack.depth)
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return (1);
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if (a->se_stack.depth < b->se_stack.depth)
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return (-1);
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for (int i = 0; i < a->se_stack.depth; i++) {
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if (a->se_stack.pcs[i] > b->se_stack.pcs[i])
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return (1);
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if (a->se_stack.pcs[i] < b->se_stack.pcs[i])
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return (-1);
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}
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return (0);
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}
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RB_HEAD(stacktree, stackentry) epoch_stacks = RB_INITIALIZER(&epoch_stacks);
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RB_GENERATE_STATIC(stacktree, stackentry, se_node, stackentry_compare);
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static struct mtx epoch_stacks_lock;
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MTX_SYSINIT(epochstacks, &epoch_stacks_lock, "epoch_stacks", MTX_DEF);
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static bool epoch_trace_stack_print = true;
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SYSCTL_BOOL(_kern_epoch, OID_AUTO, trace_stack_print, CTLFLAG_RWTUN,
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&epoch_trace_stack_print, 0, "Print stack traces on epoch reports");
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static void epoch_trace_report(const char *fmt, ...) __printflike(1, 2);
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static inline void
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epoch_trace_report(const char *fmt, ...)
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{
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va_list ap;
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struct stackentry se, *new;
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stack_save(&se.se_stack);
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/* Tree is never reduced - go lockless. */
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if (RB_FIND(stacktree, &epoch_stacks, &se) != NULL)
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return;
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new = malloc(sizeof(*new), M_STACK, M_NOWAIT);
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if (new != NULL) {
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bcopy(&se.se_stack, &new->se_stack, sizeof(struct stack));
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mtx_lock(&epoch_stacks_lock);
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new = RB_INSERT(stacktree, &epoch_stacks, new);
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mtx_unlock(&epoch_stacks_lock);
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if (new != NULL)
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free(new, M_STACK);
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}
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va_start(ap, fmt);
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(void)vprintf(fmt, ap);
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va_end(ap);
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if (epoch_trace_stack_print)
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stack_print_ddb(&se.se_stack);
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}
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static inline void
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epoch_trace_enter(struct thread *td, epoch_t epoch, epoch_tracker_t et,
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const char *file, int line)
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{
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epoch_tracker_t iet;
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SLIST_FOREACH(iet, &td->td_epochs, et_tlink) {
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if (iet->et_epoch != epoch)
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continue;
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epoch_trace_report("Recursively entering epoch %s "
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"at %s:%d, previously entered at %s:%d\n",
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epoch->e_name, file, line,
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iet->et_file, iet->et_line);
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}
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et->et_epoch = epoch;
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et->et_file = file;
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et->et_line = line;
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et->et_flags = 0;
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SLIST_INSERT_HEAD(&td->td_epochs, et, et_tlink);
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}
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static inline void
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epoch_trace_exit(struct thread *td, epoch_t epoch, epoch_tracker_t et,
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const char *file, int line)
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{
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if (SLIST_FIRST(&td->td_epochs) != et) {
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epoch_trace_report("Exiting epoch %s in a not nested order "
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"at %s:%d. Most recently entered %s at %s:%d\n",
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epoch->e_name,
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file, line,
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SLIST_FIRST(&td->td_epochs)->et_epoch->e_name,
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SLIST_FIRST(&td->td_epochs)->et_file,
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SLIST_FIRST(&td->td_epochs)->et_line);
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/* This will panic if et is not anywhere on td_epochs. */
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SLIST_REMOVE(&td->td_epochs, et, epoch_tracker, et_tlink);
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} else
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SLIST_REMOVE_HEAD(&td->td_epochs, et_tlink);
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if (et->et_flags & ET_REPORT_EXIT)
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printf("Td %p exiting epoch %s at %s:%d\n", td, epoch->e_name,
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file, line);
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}
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/* Used by assertions that check thread state before going to sleep. */
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void
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epoch_trace_list(struct thread *td)
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{
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epoch_tracker_t iet;
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SLIST_FOREACH(iet, &td->td_epochs, et_tlink)
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printf("Epoch %s entered at %s:%d\n", iet->et_epoch->e_name,
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iet->et_file, iet->et_line);
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}
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void
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epoch_where_report(epoch_t epoch)
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{
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epoch_record_t er;
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struct epoch_tracker *tdwait;
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MPASS(epoch != NULL);
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MPASS((epoch->e_flags & EPOCH_PREEMPT) != 0);
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MPASS(!THREAD_CAN_SLEEP());
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critical_enter();
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er = epoch_currecord(epoch);
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TAILQ_FOREACH(tdwait, &er->er_tdlist, et_link)
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if (tdwait->et_td == curthread)
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break;
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critical_exit();
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if (tdwait != NULL) {
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tdwait->et_flags |= ET_REPORT_EXIT;
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printf("Td %p entered epoch %s at %s:%d\n", curthread,
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epoch->e_name, tdwait->et_file, tdwait->et_line);
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}
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}
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#endif /* EPOCH_TRACE */
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static void
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epoch_init(void *arg __unused)
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{
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int cpu;
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block_count = counter_u64_alloc(M_WAITOK);
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migrate_count = counter_u64_alloc(M_WAITOK);
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turnstile_count = counter_u64_alloc(M_WAITOK);
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switch_count = counter_u64_alloc(M_WAITOK);
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epoch_call_count = counter_u64_alloc(M_WAITOK);
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epoch_call_task_count = counter_u64_alloc(M_WAITOK);
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pcpu_zone_record = uma_zcreate("epoch_record pcpu",
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sizeof(struct epoch_record), NULL, NULL, NULL, NULL,
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UMA_ALIGN_PTR, UMA_ZONE_PCPU);
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CPU_FOREACH(cpu) {
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GROUPTASK_INIT(DPCPU_ID_PTR(cpu, epoch_cb_task), 0,
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epoch_call_task, NULL);
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taskqgroup_attach_cpu(qgroup_softirq,
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DPCPU_ID_PTR(cpu, epoch_cb_task), NULL, cpu, NULL, NULL,
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"epoch call task");
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}
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#ifdef EPOCH_TRACE
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SLIST_INIT(&thread0.td_epochs);
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#endif
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sx_init(&epoch_sx, "epoch-sx");
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inited = 1;
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global_epoch = epoch_alloc("Global", 0);
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global_epoch_preempt = epoch_alloc("Global preemptible", EPOCH_PREEMPT);
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}
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SYSINIT(epoch, SI_SUB_EPOCH, SI_ORDER_FIRST, epoch_init, NULL);
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#if !defined(EARLY_AP_STARTUP)
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static void
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epoch_init_smp(void *dummy __unused)
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{
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inited = 2;
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}
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SYSINIT(epoch_smp, SI_SUB_SMP + 1, SI_ORDER_FIRST, epoch_init_smp, NULL);
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#endif
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static void
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epoch_ctor(epoch_t epoch)
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{
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epoch_record_t er;
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int cpu;
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epoch->e_pcpu_record = uma_zalloc_pcpu(pcpu_zone_record, M_WAITOK);
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CPU_FOREACH(cpu) {
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er = zpcpu_get_cpu(epoch->e_pcpu_record, cpu);
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bzero(er, sizeof(*er));
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ck_epoch_register(&epoch->e_epoch, &er->er_record, NULL);
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TAILQ_INIT((struct threadlist *)(uintptr_t)&er->er_tdlist);
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er->er_cpuid = cpu;
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er->er_parent = epoch;
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}
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}
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static void
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epoch_adjust_prio(struct thread *td, u_char prio)
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{
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thread_lock(td);
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sched_prio(td, prio);
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thread_unlock(td);
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}
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epoch_t
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epoch_alloc(const char *name, int flags)
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{
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epoch_t epoch;
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int i;
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MPASS(name != NULL);
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if (__predict_false(!inited))
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panic("%s called too early in boot", __func__);
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EPOCH_LOCK();
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/*
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* Find a free index in the epoch array. If no free index is
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* found, try to use the index after the last one.
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*/
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for (i = 0;; i++) {
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/*
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* If too many epochs are currently allocated,
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* return NULL.
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*/
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if (i == MAX_EPOCHS) {
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epoch = NULL;
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goto done;
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}
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if (epoch_array[i].e_in_use == 0)
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break;
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}
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epoch = epoch_array + i;
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ck_epoch_init(&epoch->e_epoch);
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epoch_ctor(epoch);
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epoch->e_flags = flags;
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epoch->e_name = name;
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sx_init(&epoch->e_drain_sx, "epoch-drain-sx");
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mtx_init(&epoch->e_drain_mtx, "epoch-drain-mtx", NULL, MTX_DEF);
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/*
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* Set e_in_use last, because when this field is set the
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* epoch_call_task() function will start scanning this epoch
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* structure.
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*/
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atomic_store_rel_int(&epoch->e_in_use, 1);
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done:
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EPOCH_UNLOCK();
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return (epoch);
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}
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void
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epoch_free(epoch_t epoch)
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{
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#ifdef INVARIANTS
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int cpu;
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#endif
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EPOCH_LOCK();
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MPASS(epoch->e_in_use != 0);
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epoch_drain_callbacks(epoch);
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atomic_store_rel_int(&epoch->e_in_use, 0);
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/*
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* Make sure the epoch_call_task() function see e_in_use equal
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* to zero, by calling epoch_wait() on the global_epoch:
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*/
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epoch_wait(global_epoch);
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#ifdef INVARIANTS
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CPU_FOREACH(cpu) {
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epoch_record_t er;
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er = zpcpu_get_cpu(epoch->e_pcpu_record, cpu);
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/*
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* Sanity check: none of the records should be in use anymore.
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* We drained callbacks above and freeing the pcpu records is
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* imminent.
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*/
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MPASS(er->er_td == NULL);
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MPASS(TAILQ_EMPTY(&er->er_tdlist));
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}
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#endif
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uma_zfree_pcpu(pcpu_zone_record, epoch->e_pcpu_record);
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mtx_destroy(&epoch->e_drain_mtx);
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sx_destroy(&epoch->e_drain_sx);
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memset(epoch, 0, sizeof(*epoch));
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EPOCH_UNLOCK();
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}
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#define INIT_CHECK(epoch) \
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do { \
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if (__predict_false((epoch) == NULL)) \
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return; \
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} while (0)
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|
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void
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_epoch_enter_preempt(epoch_t epoch, epoch_tracker_t et EPOCH_FILE_LINE)
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{
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struct epoch_record *er;
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struct thread *td;
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MPASS(cold || epoch != NULL);
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td = curthread;
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MPASS((vm_offset_t)et >= td->td_kstack &&
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(vm_offset_t)et + sizeof(struct epoch_tracker) <=
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td->td_kstack + td->td_kstack_pages * PAGE_SIZE);
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INIT_CHECK(epoch);
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MPASS(epoch->e_flags & EPOCH_PREEMPT);
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#ifdef EPOCH_TRACE
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epoch_trace_enter(td, epoch, et, file, line);
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#endif
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et->et_td = td;
|
|
THREAD_NO_SLEEPING();
|
|
critical_enter();
|
|
sched_pin();
|
|
et->et_old_priority = td->td_priority;
|
|
er = epoch_currecord(epoch);
|
|
/* Record-level tracking is reserved for non-preemptible epochs. */
|
|
MPASS(er->er_td == NULL);
|
|
TAILQ_INSERT_TAIL(&er->er_tdlist, et, et_link);
|
|
ck_epoch_begin(&er->er_record, &et->et_section);
|
|
critical_exit();
|
|
}
|
|
|
|
void
|
|
epoch_enter(epoch_t epoch)
|
|
{
|
|
epoch_record_t er;
|
|
|
|
MPASS(cold || epoch != NULL);
|
|
INIT_CHECK(epoch);
|
|
critical_enter();
|
|
er = epoch_currecord(epoch);
|
|
#ifdef INVARIANTS
|
|
if (er->er_record.active == 0) {
|
|
MPASS(er->er_td == NULL);
|
|
er->er_td = curthread;
|
|
} else {
|
|
/* We've recursed, just make sure our accounting isn't wrong. */
|
|
MPASS(er->er_td == curthread);
|
|
}
|
|
#endif
|
|
ck_epoch_begin(&er->er_record, NULL);
|
|
}
|
|
|
|
void
|
|
_epoch_exit_preempt(epoch_t epoch, epoch_tracker_t et EPOCH_FILE_LINE)
|
|
{
|
|
struct epoch_record *er;
|
|
struct thread *td;
|
|
|
|
INIT_CHECK(epoch);
|
|
td = curthread;
|
|
critical_enter();
|
|
sched_unpin();
|
|
THREAD_SLEEPING_OK();
|
|
er = epoch_currecord(epoch);
|
|
MPASS(epoch->e_flags & EPOCH_PREEMPT);
|
|
MPASS(et != NULL);
|
|
MPASS(et->et_td == td);
|
|
#ifdef INVARIANTS
|
|
et->et_td = (void*)0xDEADBEEF;
|
|
/* Record-level tracking is reserved for non-preemptible epochs. */
|
|
MPASS(er->er_td == NULL);
|
|
#endif
|
|
ck_epoch_end(&er->er_record, &et->et_section);
|
|
TAILQ_REMOVE(&er->er_tdlist, et, et_link);
|
|
er->er_gen++;
|
|
if (__predict_false(et->et_old_priority != td->td_priority))
|
|
epoch_adjust_prio(td, et->et_old_priority);
|
|
critical_exit();
|
|
#ifdef EPOCH_TRACE
|
|
epoch_trace_exit(td, epoch, et, file, line);
|
|
#endif
|
|
}
|
|
|
|
void
|
|
epoch_exit(epoch_t epoch)
|
|
{
|
|
epoch_record_t er;
|
|
|
|
INIT_CHECK(epoch);
|
|
er = epoch_currecord(epoch);
|
|
ck_epoch_end(&er->er_record, NULL);
|
|
#ifdef INVARIANTS
|
|
MPASS(er->er_td == curthread);
|
|
if (er->er_record.active == 0)
|
|
er->er_td = NULL;
|
|
#endif
|
|
critical_exit();
|
|
}
|
|
|
|
/*
|
|
* epoch_block_handler_preempt() is a callback from the CK code when another
|
|
* thread is currently in an epoch section.
|
|
*/
|
|
static void
|
|
epoch_block_handler_preempt(struct ck_epoch *global __unused,
|
|
ck_epoch_record_t *cr, void *arg __unused)
|
|
{
|
|
epoch_record_t record;
|
|
struct thread *td, *owner, *curwaittd;
|
|
struct epoch_tracker *tdwait;
|
|
struct turnstile *ts;
|
|
struct lock_object *lock;
|
|
int spincount, gen;
|
|
int locksheld __unused;
|
|
|
|
record = __containerof(cr, struct epoch_record, er_record);
|
|
td = curthread;
|
|
locksheld = td->td_locks;
|
|
spincount = 0;
|
|
counter_u64_add(block_count, 1);
|
|
/*
|
|
* We lost a race and there's no longer any threads
|
|
* on the CPU in an epoch section.
|
|
*/
|
|
if (TAILQ_EMPTY(&record->er_tdlist))
|
|
return;
|
|
|
|
if (record->er_cpuid != curcpu) {
|
|
/*
|
|
* If the head of the list is running, we can wait for it
|
|
* to remove itself from the list and thus save us the
|
|
* overhead of a migration
|
|
*/
|
|
gen = record->er_gen;
|
|
thread_unlock(td);
|
|
/*
|
|
* We can't actually check if the waiting thread is running
|
|
* so we simply poll for it to exit before giving up and
|
|
* migrating.
|
|
*/
|
|
do {
|
|
cpu_spinwait();
|
|
} while (!TAILQ_EMPTY(&record->er_tdlist) &&
|
|
gen == record->er_gen &&
|
|
spincount++ < MAX_ADAPTIVE_SPIN);
|
|
thread_lock(td);
|
|
/*
|
|
* If the generation has changed we can poll again
|
|
* otherwise we need to migrate.
|
|
*/
|
|
if (gen != record->er_gen)
|
|
return;
|
|
/*
|
|
* Being on the same CPU as that of the record on which
|
|
* we need to wait allows us access to the thread
|
|
* list associated with that CPU. We can then examine the
|
|
* oldest thread in the queue and wait on its turnstile
|
|
* until it resumes and so on until a grace period
|
|
* elapses.
|
|
*
|
|
*/
|
|
counter_u64_add(migrate_count, 1);
|
|
sched_bind(td, record->er_cpuid);
|
|
/*
|
|
* At this point we need to return to the ck code
|
|
* to scan to see if a grace period has elapsed.
|
|
* We can't move on to check the thread list, because
|
|
* in the meantime new threads may have arrived that
|
|
* in fact belong to a different epoch.
|
|
*/
|
|
return;
|
|
}
|
|
/*
|
|
* Try to find a thread in an epoch section on this CPU
|
|
* waiting on a turnstile. Otherwise find the lowest
|
|
* priority thread (highest prio value) and drop our priority
|
|
* to match to allow it to run.
|
|
*/
|
|
TAILQ_FOREACH(tdwait, &record->er_tdlist, et_link) {
|
|
/*
|
|
* Propagate our priority to any other waiters to prevent us
|
|
* from starving them. They will have their original priority
|
|
* restore on exit from epoch_wait().
|
|
*/
|
|
curwaittd = tdwait->et_td;
|
|
if (!TD_IS_INHIBITED(curwaittd) && curwaittd->td_priority > td->td_priority) {
|
|
critical_enter();
|
|
thread_unlock(td);
|
|
thread_lock(curwaittd);
|
|
sched_prio(curwaittd, td->td_priority);
|
|
thread_unlock(curwaittd);
|
|
thread_lock(td);
|
|
critical_exit();
|
|
}
|
|
if (TD_IS_INHIBITED(curwaittd) && TD_ON_LOCK(curwaittd) &&
|
|
((ts = curwaittd->td_blocked) != NULL)) {
|
|
/*
|
|
* We unlock td to allow turnstile_wait to reacquire
|
|
* the thread lock. Before unlocking it we enter a
|
|
* critical section to prevent preemption after we
|
|
* reenable interrupts by dropping the thread lock in
|
|
* order to prevent curwaittd from getting to run.
|
|
*/
|
|
critical_enter();
|
|
thread_unlock(td);
|
|
|
|
if (turnstile_lock(ts, &lock, &owner)) {
|
|
if (ts == curwaittd->td_blocked) {
|
|
MPASS(TD_IS_INHIBITED(curwaittd) &&
|
|
TD_ON_LOCK(curwaittd));
|
|
critical_exit();
|
|
turnstile_wait(ts, owner,
|
|
curwaittd->td_tsqueue);
|
|
counter_u64_add(turnstile_count, 1);
|
|
thread_lock(td);
|
|
return;
|
|
}
|
|
turnstile_unlock(ts, lock);
|
|
}
|
|
thread_lock(td);
|
|
critical_exit();
|
|
KASSERT(td->td_locks == locksheld,
|
|
("%d extra locks held", td->td_locks - locksheld));
|
|
}
|
|
}
|
|
/*
|
|
* We didn't find any threads actually blocked on a lock
|
|
* so we have nothing to do except context switch away.
|
|
*/
|
|
counter_u64_add(switch_count, 1);
|
|
mi_switch(SW_VOL | SWT_RELINQUISH);
|
|
/*
|
|
* It is important the thread lock is dropped while yielding
|
|
* to allow other threads to acquire the lock pointed to by
|
|
* TDQ_LOCKPTR(td). Currently mi_switch() will unlock the
|
|
* thread lock before returning. Else a deadlock like
|
|
* situation might happen.
|
|
*/
|
|
thread_lock(td);
|
|
}
|
|
|
|
void
|
|
epoch_wait_preempt(epoch_t epoch)
|
|
{
|
|
struct thread *td;
|
|
int was_bound;
|
|
int old_cpu;
|
|
int old_pinned;
|
|
u_char old_prio;
|
|
int locks __unused;
|
|
|
|
MPASS(cold || epoch != NULL);
|
|
INIT_CHECK(epoch);
|
|
td = curthread;
|
|
#ifdef INVARIANTS
|
|
locks = curthread->td_locks;
|
|
MPASS(epoch->e_flags & EPOCH_PREEMPT);
|
|
if ((epoch->e_flags & EPOCH_LOCKED) == 0)
|
|
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
|
|
"epoch_wait() can be long running");
|
|
KASSERT(!in_epoch(epoch), ("epoch_wait_preempt() called in the middle "
|
|
"of an epoch section of the same epoch"));
|
|
#endif
|
|
DROP_GIANT();
|
|
thread_lock(td);
|
|
|
|
old_cpu = PCPU_GET(cpuid);
|
|
old_pinned = td->td_pinned;
|
|
old_prio = td->td_priority;
|
|
was_bound = sched_is_bound(td);
|
|
sched_unbind(td);
|
|
td->td_pinned = 0;
|
|
sched_bind(td, old_cpu);
|
|
|
|
ck_epoch_synchronize_wait(&epoch->e_epoch, epoch_block_handler_preempt,
|
|
NULL);
|
|
|
|
/* restore CPU binding, if any */
|
|
if (was_bound != 0) {
|
|
sched_bind(td, old_cpu);
|
|
} else {
|
|
/* get thread back to initial CPU, if any */
|
|
if (old_pinned != 0)
|
|
sched_bind(td, old_cpu);
|
|
sched_unbind(td);
|
|
}
|
|
/* restore pinned after bind */
|
|
td->td_pinned = old_pinned;
|
|
|
|
/* restore thread priority */
|
|
sched_prio(td, old_prio);
|
|
thread_unlock(td);
|
|
PICKUP_GIANT();
|
|
KASSERT(td->td_locks == locks,
|
|
("%d residual locks held", td->td_locks - locks));
|
|
}
|
|
|
|
static void
|
|
epoch_block_handler(struct ck_epoch *g __unused, ck_epoch_record_t *c __unused,
|
|
void *arg __unused)
|
|
{
|
|
cpu_spinwait();
|
|
}
|
|
|
|
void
|
|
epoch_wait(epoch_t epoch)
|
|
{
|
|
|
|
MPASS(cold || epoch != NULL);
|
|
INIT_CHECK(epoch);
|
|
MPASS(epoch->e_flags == 0);
|
|
critical_enter();
|
|
ck_epoch_synchronize_wait(&epoch->e_epoch, epoch_block_handler, NULL);
|
|
critical_exit();
|
|
}
|
|
|
|
void
|
|
epoch_call(epoch_t epoch, epoch_callback_t callback, epoch_context_t ctx)
|
|
{
|
|
epoch_record_t er;
|
|
ck_epoch_entry_t *cb;
|
|
|
|
cb = (void *)ctx;
|
|
|
|
MPASS(callback);
|
|
/* too early in boot to have epoch set up */
|
|
if (__predict_false(epoch == NULL))
|
|
goto boottime;
|
|
#if !defined(EARLY_AP_STARTUP)
|
|
if (__predict_false(inited < 2))
|
|
goto boottime;
|
|
#endif
|
|
|
|
critical_enter();
|
|
*DPCPU_PTR(epoch_cb_count) += 1;
|
|
er = epoch_currecord(epoch);
|
|
ck_epoch_call(&er->er_record, cb, (ck_epoch_cb_t *)callback);
|
|
critical_exit();
|
|
return;
|
|
boottime:
|
|
callback(ctx);
|
|
}
|
|
|
|
static void
|
|
epoch_call_task(void *arg __unused)
|
|
{
|
|
ck_stack_entry_t *cursor, *head, *next;
|
|
ck_epoch_record_t *record;
|
|
epoch_record_t er;
|
|
epoch_t epoch;
|
|
ck_stack_t cb_stack;
|
|
int i, npending, total;
|
|
|
|
ck_stack_init(&cb_stack);
|
|
critical_enter();
|
|
epoch_enter(global_epoch);
|
|
for (total = i = 0; i != MAX_EPOCHS; i++) {
|
|
epoch = epoch_array + i;
|
|
if (__predict_false(
|
|
atomic_load_acq_int(&epoch->e_in_use) == 0))
|
|
continue;
|
|
er = epoch_currecord(epoch);
|
|
record = &er->er_record;
|
|
if ((npending = record->n_pending) == 0)
|
|
continue;
|
|
ck_epoch_poll_deferred(record, &cb_stack);
|
|
total += npending - record->n_pending;
|
|
}
|
|
epoch_exit(global_epoch);
|
|
*DPCPU_PTR(epoch_cb_count) -= total;
|
|
critical_exit();
|
|
|
|
counter_u64_add(epoch_call_count, total);
|
|
counter_u64_add(epoch_call_task_count, 1);
|
|
|
|
head = ck_stack_batch_pop_npsc(&cb_stack);
|
|
for (cursor = head; cursor != NULL; cursor = next) {
|
|
struct ck_epoch_entry *entry =
|
|
ck_epoch_entry_container(cursor);
|
|
|
|
next = CK_STACK_NEXT(cursor);
|
|
entry->function(entry);
|
|
}
|
|
}
|
|
|
|
static int
|
|
in_epoch_verbose_preempt(epoch_t epoch, int dump_onfail)
|
|
{
|
|
epoch_record_t er;
|
|
struct epoch_tracker *tdwait;
|
|
struct thread *td;
|
|
|
|
MPASS(epoch != NULL);
|
|
MPASS((epoch->e_flags & EPOCH_PREEMPT) != 0);
|
|
td = curthread;
|
|
if (THREAD_CAN_SLEEP())
|
|
return (0);
|
|
critical_enter();
|
|
er = epoch_currecord(epoch);
|
|
TAILQ_FOREACH(tdwait, &er->er_tdlist, et_link)
|
|
if (tdwait->et_td == td) {
|
|
critical_exit();
|
|
return (1);
|
|
}
|
|
#ifdef INVARIANTS
|
|
if (dump_onfail) {
|
|
MPASS(td->td_pinned);
|
|
printf("cpu: %d id: %d\n", curcpu, td->td_tid);
|
|
TAILQ_FOREACH(tdwait, &er->er_tdlist, et_link)
|
|
printf("td_tid: %d ", tdwait->et_td->td_tid);
|
|
printf("\n");
|
|
}
|
|
#endif
|
|
critical_exit();
|
|
return (0);
|
|
}
|
|
|
|
#ifdef INVARIANTS
|
|
static void
|
|
epoch_assert_nocpu(epoch_t epoch, struct thread *td)
|
|
{
|
|
epoch_record_t er;
|
|
int cpu;
|
|
bool crit;
|
|
|
|
crit = td->td_critnest > 0;
|
|
|
|
/* Check for a critical section mishap. */
|
|
CPU_FOREACH(cpu) {
|
|
er = zpcpu_get_cpu(epoch->e_pcpu_record, cpu);
|
|
KASSERT(er->er_td != td,
|
|
("%s critical section in epoch '%s', from cpu %d",
|
|
(crit ? "exited" : "re-entered"), epoch->e_name, cpu));
|
|
}
|
|
}
|
|
#else
|
|
#define epoch_assert_nocpu(e, td) do {} while (0)
|
|
#endif
|
|
|
|
int
|
|
in_epoch_verbose(epoch_t epoch, int dump_onfail)
|
|
{
|
|
epoch_record_t er;
|
|
struct thread *td;
|
|
|
|
if (__predict_false((epoch) == NULL))
|
|
return (0);
|
|
if ((epoch->e_flags & EPOCH_PREEMPT) != 0)
|
|
return (in_epoch_verbose_preempt(epoch, dump_onfail));
|
|
|
|
/*
|
|
* The thread being in a critical section is a necessary
|
|
* condition to be correctly inside a non-preemptible epoch,
|
|
* so it's definitely not in this epoch.
|
|
*/
|
|
td = curthread;
|
|
if (td->td_critnest == 0) {
|
|
epoch_assert_nocpu(epoch, td);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* The current cpu is in a critical section, so the epoch record will be
|
|
* stable for the rest of this function. Knowing that the record is not
|
|
* active is sufficient for knowing whether we're in this epoch or not,
|
|
* since it's a pcpu record.
|
|
*/
|
|
er = epoch_currecord(epoch);
|
|
if (er->er_record.active == 0) {
|
|
epoch_assert_nocpu(epoch, td);
|
|
return (0);
|
|
}
|
|
|
|
MPASS(er->er_td == td);
|
|
return (1);
|
|
}
|
|
|
|
int
|
|
in_epoch(epoch_t epoch)
|
|
{
|
|
return (in_epoch_verbose(epoch, 0));
|
|
}
|
|
|
|
static void
|
|
epoch_drain_cb(struct epoch_context *ctx)
|
|
{
|
|
struct epoch *epoch =
|
|
__containerof(ctx, struct epoch_record, er_drain_ctx)->er_parent;
|
|
|
|
if (atomic_fetchadd_int(&epoch->e_drain_count, -1) == 1) {
|
|
mtx_lock(&epoch->e_drain_mtx);
|
|
wakeup(epoch);
|
|
mtx_unlock(&epoch->e_drain_mtx);
|
|
}
|
|
}
|
|
|
|
void
|
|
epoch_drain_callbacks(epoch_t epoch)
|
|
{
|
|
epoch_record_t er;
|
|
struct thread *td;
|
|
int was_bound;
|
|
int old_pinned;
|
|
int old_cpu;
|
|
int cpu;
|
|
|
|
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
|
|
"epoch_drain_callbacks() may sleep!");
|
|
|
|
/* too early in boot to have epoch set up */
|
|
if (__predict_false(epoch == NULL))
|
|
return;
|
|
#if !defined(EARLY_AP_STARTUP)
|
|
if (__predict_false(inited < 2))
|
|
return;
|
|
#endif
|
|
DROP_GIANT();
|
|
|
|
sx_xlock(&epoch->e_drain_sx);
|
|
mtx_lock(&epoch->e_drain_mtx);
|
|
|
|
td = curthread;
|
|
thread_lock(td);
|
|
old_cpu = PCPU_GET(cpuid);
|
|
old_pinned = td->td_pinned;
|
|
was_bound = sched_is_bound(td);
|
|
sched_unbind(td);
|
|
td->td_pinned = 0;
|
|
|
|
CPU_FOREACH(cpu)
|
|
epoch->e_drain_count++;
|
|
CPU_FOREACH(cpu) {
|
|
er = zpcpu_get_cpu(epoch->e_pcpu_record, cpu);
|
|
sched_bind(td, cpu);
|
|
epoch_call(epoch, &epoch_drain_cb, &er->er_drain_ctx);
|
|
}
|
|
|
|
/* restore CPU binding, if any */
|
|
if (was_bound != 0) {
|
|
sched_bind(td, old_cpu);
|
|
} else {
|
|
/* get thread back to initial CPU, if any */
|
|
if (old_pinned != 0)
|
|
sched_bind(td, old_cpu);
|
|
sched_unbind(td);
|
|
}
|
|
/* restore pinned after bind */
|
|
td->td_pinned = old_pinned;
|
|
|
|
thread_unlock(td);
|
|
|
|
while (epoch->e_drain_count != 0)
|
|
msleep(epoch, &epoch->e_drain_mtx, PZERO, "EDRAIN", 0);
|
|
|
|
mtx_unlock(&epoch->e_drain_mtx);
|
|
sx_xunlock(&epoch->e_drain_sx);
|
|
|
|
PICKUP_GIANT();
|
|
}
|