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Add full support support for dynamic allocation and freeing of epoch's.

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Make sure to reclaim epoch structures when they are freed to support
dynamic allocation and freeing of epoch structures.

While at it, move the 64 supported epoch control structures to the
static memory domain. This overall simplifies the management and
debugging of system epoch's.

Reviewed by:		kib, markj
Differential Revision:	https://reviews.freebsd.org/D25960
MFC after:		1 week
Sponsored by:		Mellanox Technologies
This commit is contained in:
Hans Petter Selasky 2020-08-07 15:32:42 +00:00
parent a9839c4aee
commit 826c079373
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=364019
1 changed files with 58 additions and 13 deletions
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71
sys/kern/subr_epoch.c
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@ -58,8 +58,6 @@ __FBSDID("$FreeBSD$");
#include <ck_epoch.h>
static MALLOC_DEFINE(M_EPOCH, "epoch", "epoch based reclamation");
#ifdef __amd64__
#define EPOCH_ALIGN CACHE_LINE_SIZE*2
#else
@ -79,7 +77,7 @@ typedef struct epoch_record {
struct epoch {
struct ck_epoch e_epoch __aligned(EPOCH_ALIGN);
epoch_record_t e_pcpu_record;
int e_idx;
int e_in_use;
int e_flags;
struct sx e_drain_sx;
struct mtx e_drain_mtx;
@ -128,19 +126,23 @@ TAILQ_HEAD (threadlist, thread);
CK_STACK_CONTAINER(struct ck_epoch_entry, stack_entry,
ck_epoch_entry_container)
epoch_t allepochs[MAX_EPOCHS];
static struct epoch epoch_array[MAX_EPOCHS];
DPCPU_DEFINE(struct grouptask, epoch_cb_task);
DPCPU_DEFINE(int, epoch_cb_count);
static __read_mostly int inited;
static __read_mostly int epoch_count;
__read_mostly epoch_t global_epoch;
__read_mostly epoch_t global_epoch_preempt;
static void epoch_call_task(void *context __unused);
static uma_zone_t pcpu_zone_record;
static struct sx epoch_sx;
#define EPOCH_LOCK() sx_xlock(&epoch_sx)
#define EPOCH_UNLOCK() sx_xunlock(&epoch_sx)
#ifdef EPOCH_TRACE
struct stackentry {
RB_ENTRY(stackentry) se_node;
@ -281,6 +283,7 @@ epoch_init(void *arg __unused)
#ifdef EPOCH_TRACE
SLIST_INIT(&thread0.td_epochs);
#endif
sx_init(&epoch_sx, "epoch-sx");
inited = 1;
global_epoch = epoch_alloc("Global", 0);
global_epoch_preempt = epoch_alloc("Global preemptible", EPOCH_PREEMPT);
@ -326,19 +329,48 @@ epoch_t
epoch_alloc(const char *name, int flags)
{
epoch_t epoch;
int i;
MPASS(name != NULL);
if (__predict_false(!inited))
panic("%s called too early in boot", __func__);
epoch = malloc(sizeof(struct epoch), M_EPOCH, M_ZERO | M_WAITOK);
EPOCH_LOCK();
/*
* Find a free index in the epoch array. If no free index is
* found, try to use the index after the last one.
*/
for (i = 0;; i++) {
/*
* If too many epochs are currently allocated,
* return NULL.
*/
if (i == MAX_EPOCHS) {
epoch = NULL;
goto done;
}
if (epoch_array[i].e_in_use == 0)
break;
}
epoch = epoch_array + i;
ck_epoch_init(&epoch->e_epoch);
epoch_ctor(epoch);
MPASS(epoch_count < MAX_EPOCHS - 2);
epoch->e_flags = flags;
epoch->e_idx = epoch_count;
epoch->e_name = name;
sx_init(&epoch->e_drain_sx, "epoch-drain-sx");
mtx_init(&epoch->e_drain_mtx, "epoch-drain-mtx", NULL, MTX_DEF);
allepochs[epoch_count++] = epoch;
/*
* Set e_in_use last, because when this field is set the
* epoch_call_task() function will start scanning this epoch
* structure.
*/
atomic_store_rel_int(&epoch->e_in_use, 1);
done:
EPOCH_UNLOCK();
return (epoch);
}
@ -346,13 +378,24 @@ void
epoch_free(epoch_t epoch)
{
EPOCH_LOCK();
MPASS(epoch->e_in_use != 0);
epoch_drain_callbacks(epoch);
allepochs[epoch->e_idx] = NULL;
atomic_store_rel_int(&epoch->e_in_use, 0);
/*
* Make sure the epoch_call_task() function see e_in_use equal
* to zero, by calling epoch_wait() on the global_epoch:
*/
epoch_wait(global_epoch);
uma_zfree_pcpu(pcpu_zone_record, epoch->e_pcpu_record);
mtx_destroy(&epoch->e_drain_mtx);
sx_destroy(&epoch->e_drain_sx);
free(epoch, M_EPOCH);
memset(epoch, 0, sizeof(*epoch));
EPOCH_UNLOCK();
}
static epoch_record_t
@ -705,8 +748,10 @@ epoch_call_task(void *arg __unused)
ck_stack_init(&cb_stack);
critical_enter();
epoch_enter(global_epoch);
for (total = i = 0; i < epoch_count; i++) {
if (__predict_false((epoch = allepochs[i]) == NULL))
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;