diff options
Diffstat (limited to 'erts/emulator/beam/erl_flxctr.c')
| -rw-r--r-- | erts/emulator/beam/erl_flxctr.c | 370 |
1 files changed, 370 insertions, 0 deletions
diff --git a/erts/emulator/beam/erl_flxctr.c b/erts/emulator/beam/erl_flxctr.c new file mode 100644 index 0000000000..35f4a21508 --- /dev/null +++ b/erts/emulator/beam/erl_flxctr.c @@ -0,0 +1,370 @@ +/* + * %CopyrightBegin% + * + * Copyright Ericsson AB 2019. All Rights Reserved. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * %CopyrightEnd% + */ + +/* + * Author: Kjell Winblad + */ + +#include "erl_flxctr.h" + +static int reader_groups_array_size = 0; +#define ERTS_FLXCTR_DECENTRALIZED_NO_SLOTS (reader_groups_array_size) + +static int erts_flxctr_read_ctx_bin_dtor(Binary *context_bin); +static int erts_flxctr_wait_dtor(Binary *context_bin); + +typedef struct { + ErtsThrPrgrLaterOp later_op; + Process* process; + ErtsFlxCtrDecentralizedCtrArray* array; + ErtsFlxCtrDecentralizedCtrArray* next_array; + ErtsAlcType_t alloc_type; + int nr_of_counters; + Sint result[ERTS_FLXCTR_ATOMICS_PER_CACHE_LINE]; +} DecentralizedReadSnapshotInfo; + +typedef enum { + ERTS_FLXCTR_SNAPSHOT_NOT_ONGOING = 0, + ERTS_FLXCTR_SNAPSHOT_ONGOING = 1, + ERTS_FLXCTR_SNAPSHOT_ONGOING_TP_THREAD_DO_FREE = 2 +} erts_flxctr_snapshot_status; + +static void +thr_prg_wake_up_and_count(void* bin_p) +{ + Binary* bin = bin_p; + DecentralizedReadSnapshotInfo* info = ERTS_MAGIC_BIN_DATA(bin); + Process* p = info->process; + ErtsFlxCtrDecentralizedCtrArray* array = info->array; + ErtsFlxCtrDecentralizedCtrArray* next = info->next_array; + int i, sched; + /* Reset result array */ + for (i = 0; i < info->nr_of_counters; i++) { + info->result[i] = 0; + } + /* Read result from snapshot */ + for (sched = 0; sched < ERTS_FLXCTR_DECENTRALIZED_NO_SLOTS; sched++) { + for (i = 0; i < info->nr_of_counters; i++) { + info->result[i] = info->result[i] + + erts_atomic_read_nob(&array->array[sched].counters[i]); + } + } + /* Update the next decentralized counter array */ + for (i = 0; i < info->nr_of_counters; i++) { + erts_atomic_add_nob(&next->array[0].counters[i], info->result[i]); + } + /* Announce that the snapshot is done */ + { + Sint expected = ERTS_FLXCTR_SNAPSHOT_ONGOING; + if (expected != erts_atomic_cmpxchg_mb(&next->snapshot_status, + ERTS_FLXCTR_SNAPSHOT_NOT_ONGOING, + expected)) { + /* The CAS failed which means that this thread need to free the next array. */ + erts_free(info->alloc_type, next->block_start); + } + } + /* Resume the process that requested the snapshot */ + erts_proc_lock(p, ERTS_PROC_LOCK_STATUS); + if (!ERTS_PROC_IS_EXITING(p)) { + erts_resume(p, ERTS_PROC_LOCK_STATUS); + } + /* Free the memory that is no longer needed */ + erts_free(info->alloc_type, array->block_start); + erts_proc_unlock(p, ERTS_PROC_LOCK_STATUS); + erts_proc_dec_refc(p); + erts_bin_release(bin); +} + +typedef struct { + ErtsThrPrgrLaterOp later_op; + Process* process; +} ErtsFlxCtrWakeUpLaterInfo; + +static void +thr_prg_wake_up_later(void* bin_p) +{ + Binary* bin = bin_p; + ErtsFlxCtrWakeUpLaterInfo* info = ERTS_MAGIC_BIN_DATA(bin); + Process* p = info->process; + /* Resume the requesting process */ + erts_proc_lock(p, ERTS_PROC_LOCK_STATUS); + if (!ERTS_PROC_IS_EXITING(p)) { + erts_resume(p, ERTS_PROC_LOCK_STATUS); + } + erts_proc_unlock(p, ERTS_PROC_LOCK_STATUS); + /* Free data */ + erts_proc_dec_refc(p); + erts_bin_release(bin); +} + +static +int erts_flxctr_read_ctx_bin_dtor(Binary *context_bin) { + (void)context_bin; + return 1; +} + +static +int erts_flxctr_wait_dtor(Binary *context_bin) { + (void)context_bin; + return 1; +} + +static void suspend_until_thr_prg(Process* p) +{ + Binary* state_bin; + ErtsFlxCtrWakeUpLaterInfo* info; + state_bin = erts_create_magic_binary(sizeof(ErtsFlxCtrWakeUpLaterInfo), + erts_flxctr_wait_dtor); + info = ERTS_MAGIC_BIN_DATA(state_bin); + info->process = p; + erts_refc_inctest(&state_bin->intern.refc, 1); + erts_suspend(p, ERTS_PROC_LOCK_MAIN, NULL); + erts_proc_inc_refc(p); + ERTS_VBUMP_ALL_REDS(p); + erts_schedule_thr_prgr_later_op(thr_prg_wake_up_later, state_bin, &info->later_op); +} + + +static ErtsFlxCtrDecentralizedCtrArray* +create_decentralized_ctr_array(ErtsAlcType_t alloc_type, Uint nr_of_counters) { + /* Allocate an ErtsFlxCtrDecentralizedCtrArray and make sure that + the array field is located at the start of a cache line */ + char* bytes = + erts_alloc(alloc_type, + sizeof(ErtsFlxCtrDecentralizedCtrArray) + + (sizeof(ErtsFlxCtrDecentralizedCtrArrayElem) * + ERTS_FLXCTR_DECENTRALIZED_NO_SLOTS) + + ERTS_CACHE_LINE_SIZE); + void* block_start = bytes; + int bytes_to_next_cacheline_border; + ErtsFlxCtrDecentralizedCtrArray* array; + int i, sched; + bytes = &bytes[offsetof(ErtsFlxCtrDecentralizedCtrArray, array)]; + bytes_to_next_cacheline_border = + ERTS_CACHE_LINE_SIZE - (((Uint)bytes) % ERTS_CACHE_LINE_SIZE); + array = (ErtsFlxCtrDecentralizedCtrArray*) + (&bytes[bytes_to_next_cacheline_border - + (int)offsetof(ErtsFlxCtrDecentralizedCtrArray, array)]); + ASSERT(((Uint)array->array) % ERTS_CACHE_LINE_SIZE == 0); + ASSERT(((Uint)array - (Uint)block_start) <= ERTS_CACHE_LINE_SIZE); + /* Initialize fields */ + erts_atomic_init_nob(&array->snapshot_status, ERTS_FLXCTR_SNAPSHOT_ONGOING); + for (sched = 0; sched < ERTS_FLXCTR_DECENTRALIZED_NO_SLOTS; sched++) { + for (i = 0; i < nr_of_counters; i++) { + erts_atomic_init_nob(&array->array[sched].counters[i], 0); + } + } + array->block_start = block_start; + return array; +} + +void erts_flxctr_setup(int decentralized_counter_groups) +{ + reader_groups_array_size = decentralized_counter_groups+1; +} + +void erts_flxctr_init(ErtsFlxCtr* c, + int is_decentralized, + Uint nr_of_counters, + ErtsAlcType_t alloc_type) +{ + ASSERT(nr_of_counters <= ERTS_FLXCTR_ATOMICS_PER_CACHE_LINE); + c->is_decentralized = is_decentralized; + c->nr_of_counters = nr_of_counters; + if (c->is_decentralized) { + ErtsFlxCtrDecentralizedCtrArray* array = + create_decentralized_ctr_array(alloc_type, nr_of_counters); + erts_atomic_set_nob(&array->snapshot_status, + ERTS_FLXCTR_SNAPSHOT_NOT_ONGOING); + erts_atomic_init_nob(&c->u.counters_ptr, (Sint)array); + ASSERT(((Uint)array->array) % ERTS_CACHE_LINE_SIZE == 0); + } else { + int i; + for (i = 0; i < nr_of_counters; i++) { + erts_atomic_init_nob(&c->u.counters[i], 0); + } + } +} + +void erts_flxctr_destroy(ErtsFlxCtr* c, ErtsAlcType_t type) +{ + if (c->is_decentralized) { + if (erts_flxctr_is_snapshot_ongoing(c)) { + ErtsFlxCtrDecentralizedCtrArray* array = + ERTS_FLXCTR_GET_CTR_ARRAY_PTR(c); + /* Try to delegate the resposibilty of freeing to + thr_prg_wake_up_and_count */ + Sint expected = ERTS_FLXCTR_SNAPSHOT_ONGOING; + if (expected != + erts_atomic_cmpxchg_mb(&array->snapshot_status, + ERTS_FLXCTR_SNAPSHOT_ONGOING_TP_THREAD_DO_FREE, + expected)) { + /* The delegation was unsuccessful which means that no + snapshot is ongoing anymore and the freeing needs + to be done here */ + ERTS_ASSERT(!erts_flxctr_is_snapshot_ongoing(c)); + erts_free(type, array->block_start); + } + } else { + erts_free(type, ERTS_FLXCTR_GET_CTR_ARRAY_PTR(c)->block_start); + } + } +} + +ErtsFlxCtrSnapshotResult +erts_flxctr_snapshot(ErtsFlxCtr* c, + ErtsAlcType_t alloc_type, + Process* p) +{ + if (c->is_decentralized) { + ErtsFlxCtrDecentralizedCtrArray* array = ERTS_FLXCTR_GET_CTR_ARRAY_PTR(c); + if (erts_flxctr_is_snapshot_ongoing(c)) { + /* Let the caller try again later */ + ErtsFlxCtrSnapshotResult res = + {.type = ERTS_FLXCTR_TRY_AGAIN_AFTER_TRAP}; + suspend_until_thr_prg(p); + return res; + } else { + Eterm* hp; + Binary* state_bin; + Eterm state_mref; + DecentralizedReadSnapshotInfo* info; + ErtsFlxCtrDecentralizedCtrArray* new_array = + create_decentralized_ctr_array(alloc_type, c->nr_of_counters); + int success = + ((Sint)array) == erts_atomic_cmpxchg_mb(&c->u.counters_ptr, + (Sint)new_array, + (Sint)array); + if (!success) { + /* Let the caller try again later */ + ErtsFlxCtrSnapshotResult res = + {.type = ERTS_FLXCTR_TRY_AGAIN_AFTER_TRAP}; + suspend_until_thr_prg(p); + erts_free(alloc_type, new_array->block_start); + return res; + } + /* Create binary with info about the operation that can be + sent to the caller and to a thread progress function */ + state_bin = + erts_create_magic_binary(sizeof(DecentralizedReadSnapshotInfo), + erts_flxctr_read_ctx_bin_dtor); + hp = HAlloc(p, ERTS_MAGIC_REF_THING_SIZE); + state_mref = erts_mk_magic_ref(&hp, &MSO(p), state_bin); + info = ERTS_MAGIC_BIN_DATA(state_bin); + info->alloc_type = alloc_type; + info->array = array; + info->next_array = new_array; + info->process = p; + info->nr_of_counters = c->nr_of_counters; + erts_proc_inc_refc(p); + erts_refc_inctest(&state_bin->intern.refc, 2); + erts_suspend(p, ERTS_PROC_LOCK_MAIN, NULL); + ERTS_VBUMP_ALL_REDS(p); + erts_schedule_thr_prgr_later_op(thr_prg_wake_up_and_count, + state_bin, + &info->later_op); + { + ErtsFlxCtrSnapshotResult res = { + .type = ERTS_FLXCTR_GET_RESULT_AFTER_TRAP, + .trap_resume_state = state_mref}; + return res; + } + } + } else { + ErtsFlxCtrSnapshotResult res; + int i; + res.type = ERTS_FLXCTR_DONE; + for (i = 0; i < c->nr_of_counters; i++){ + res.result[i] = erts_flxctr_read_centralized(c, i); + } + return res; + } +} + + +Sint erts_flxctr_get_snapshot_result_after_trap(Eterm result_holder, + Uint counter_nr) +{ + Binary* bin = erts_magic_ref2bin(result_holder); + DecentralizedReadSnapshotInfo* data = ERTS_MAGIC_BIN_DATA(bin);; + return data->result[counter_nr]; +} + +int erts_flxctr_is_snapshot_result(Eterm term) +{ + if (is_internal_magic_ref(term)) { + Binary* bin = erts_magic_ref2bin(term); + return ERTS_MAGIC_BIN_DESTRUCTOR(bin) == erts_flxctr_read_ctx_bin_dtor; + } else return 0; +} + +Sint erts_flxctr_read_approx(ErtsFlxCtr* c, + Uint counter_nr) +{ + if (c->is_decentralized) { + ErtsFlxCtrDecentralizedCtrArray* counter = ERTS_FLXCTR_GET_CTR_ARRAY_PTR(c); + Sint sum = 0; + int sched; + for (sched = 0; sched < ERTS_FLXCTR_DECENTRALIZED_NO_SLOTS; sched++) { + sum = sum + erts_atomic_read_nob(&counter->array[sched].counters[counter_nr]); + } + return sum; + } else { + return erts_flxctr_read_centralized(c, counter_nr); + } +} + +int erts_flxctr_is_snapshot_ongoing(ErtsFlxCtr* c) +{ + return c->is_decentralized && + (ERTS_FLXCTR_SNAPSHOT_NOT_ONGOING != + erts_atomic_read_acqb(&ERTS_FLXCTR_GET_CTR_ARRAY_PTR(c)->snapshot_status)); +} + +int erts_flxctr_suspend_until_thr_prg_if_snapshot_ongoing(ErtsFlxCtr* c, Process* p) +{ + if (erts_flxctr_is_snapshot_ongoing(c)) { + suspend_until_thr_prg(p); + return 1; + } else { + return 0; + } +} + +void erts_flxctr_reset(ErtsFlxCtr* c, + Uint counter_nr) +{ + if (c->is_decentralized) { + int sched; + ErtsFlxCtrDecentralizedCtrArray* counter = + ERTS_FLXCTR_GET_CTR_ARRAY_PTR(c); + for (sched = 0; sched < ERTS_FLXCTR_DECENTRALIZED_NO_SLOTS; sched++) { + erts_atomic_set_nob(&counter->array[sched].counters[counter_nr], 0); + } + } else { + erts_atomic_set_nob(&c->u.counters[counter_nr], 0); + } +} + + +void erts_flxctr_set_slot(int group) { + ErtsSchedulerData *esdp = erts_get_scheduler_data(); + esdp->flxctr_slot_no = group; +} |