+++ /dev/null
-/*
- * SPDX-License-Identifier: LGPL-2.1-or-later
- *
- * Copyright 2011 Lai Jiangshan <laijs@cn.fujitsu.com>
- *
- * mmap/reservation based memory management for Lock-Free RCU Hash Table
- */
-
-#include <unistd.h>
-#include <stdio.h>
-#include <errno.h>
-#include <stdlib.h>
-#include <sys/mman.h>
-#include "rculfhash-internal.h"
-
-#ifndef MAP_ANONYMOUS
-#define MAP_ANONYMOUS MAP_ANON
-#endif
-
-/*
- * The allocation scheme used by the mmap based RCU hash table is to make a
- * large unaccessible mapping to reserve memory without allocating it.
- * Then smaller chunks are allocated by overlapping read/write mappings which
- * do allocate memory. Deallocation is done by an overlapping unaccessible
- * mapping.
- *
- * This scheme was tested on Linux, macOS and Solaris. However, on Cygwin the
- * mmap wrapper is based on the Windows NtMapViewOfSection API which doesn't
- * support overlapping mappings.
- *
- * An alternative to the overlapping mappings is to use mprotect to change the
- * protection on chunks of the large mapping, read/write to allocate and none
- * to deallocate. This works perfecty on Cygwin and Solaris but on Linux a
- * call to madvise is also required to deallocate and it just doesn't work on
- * macOS.
- *
- * For this reason, we keep to original scheme on all platforms except Cygwin.
- */
-
-
-/* Reserve inaccessible memory space without allocating it */
-static
-void *memory_map(size_t length)
-{
- void *ret;
-
- ret = mmap(NULL, length, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
- if (ret == MAP_FAILED) {
- perror("mmap");
- abort();
- }
- return ret;
-}
-
-static
-void memory_unmap(void *ptr, size_t length)
-{
- if (munmap(ptr, length)) {
- perror("munmap");
- abort();
- }
-}
-
-#ifdef __CYGWIN__
-/* Set protection to read/write to allocate a memory chunk */
-static
-void memory_populate(void *ptr, size_t length)
-{
- if (mprotect(ptr, length, PROT_READ | PROT_WRITE)) {
- perror("mprotect");
- abort();
- }
-}
-
-/* Set protection to none to deallocate a memory chunk */
-static
-void memory_discard(void *ptr, size_t length)
-{
- if (mprotect(ptr, length, PROT_NONE)) {
- perror("mprotect");
- abort();
- }
-}
-
-#else /* __CYGWIN__ */
-
-static
-void memory_populate(void *ptr, size_t length)
-{
- if (mmap(ptr, length, PROT_READ | PROT_WRITE,
- MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
- -1, 0) != ptr) {
- perror("mmap");
- abort();
- }
-}
-
-/*
- * Discard garbage memory and avoid system save it when try to swap it out.
- * Make it still reserved, inaccessible.
- */
-static
-void memory_discard(void *ptr, size_t length)
-{
- if (mmap(ptr, length, PROT_NONE,
- MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
- -1, 0) != ptr) {
- perror("mmap");
- abort();
- }
-}
-#endif /* __CYGWIN__ */
-
-static
-void lttng_ust_lfht_alloc_bucket_table(struct lttng_ust_lfht *ht, unsigned long order)
-{
- if (order == 0) {
- if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) {
- /* small table */
- ht->tbl_mmap = calloc(ht->max_nr_buckets,
- sizeof(*ht->tbl_mmap));
- assert(ht->tbl_mmap);
- return;
- }
- /* large table */
- ht->tbl_mmap = memory_map(ht->max_nr_buckets
- * sizeof(*ht->tbl_mmap));
- memory_populate(ht->tbl_mmap,
- ht->min_nr_alloc_buckets * sizeof(*ht->tbl_mmap));
- } else if (order > ht->min_alloc_buckets_order) {
- /* large table */
- unsigned long len = 1UL << (order - 1);
-
- assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets);
- memory_populate(ht->tbl_mmap + len,
- len * sizeof(*ht->tbl_mmap));
- }
- /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
-}
-
-/*
- * lttng_ust_lfht_free_bucket_table() should be called with decreasing order.
- * When lttng_ust_lfht_free_bucket_table(0) is called, it means the whole
- * lfht is destroyed.
- */
-static
-void lttng_ust_lfht_free_bucket_table(struct lttng_ust_lfht *ht, unsigned long order)
-{
- if (order == 0) {
- if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) {
- /* small table */
- poison_free(ht->tbl_mmap);
- return;
- }
- /* large table */
- memory_unmap(ht->tbl_mmap,
- ht->max_nr_buckets * sizeof(*ht->tbl_mmap));
- } else if (order > ht->min_alloc_buckets_order) {
- /* large table */
- unsigned long len = 1UL << (order - 1);
-
- assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets);
- memory_discard(ht->tbl_mmap + len, len * sizeof(*ht->tbl_mmap));
- }
- /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
-}
-
-static
-struct lttng_ust_lfht_node *bucket_at(struct lttng_ust_lfht *ht, unsigned long index)
-{
- return &ht->tbl_mmap[index];
-}
-
-static
-struct lttng_ust_lfht *alloc_lttng_ust_lfht(unsigned long min_nr_alloc_buckets,
- unsigned long max_nr_buckets)
-{
- unsigned long page_bucket_size;
-
- page_bucket_size = getpagesize() / sizeof(struct lttng_ust_lfht_node);
- if (max_nr_buckets <= page_bucket_size) {
- /* small table */
- min_nr_alloc_buckets = max_nr_buckets;
- } else {
- /* large table */
- min_nr_alloc_buckets = max(min_nr_alloc_buckets,
- page_bucket_size);
- }
-
- return __default_alloc_lttng_ust_lfht(
- <tng_ust_lfht_mm_mmap, sizeof(struct lttng_ust_lfht),
- min_nr_alloc_buckets, max_nr_buckets);
-}
-
-const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_mmap = {
- .alloc_lttng_ust_lfht = alloc_lttng_ust_lfht,
- .alloc_bucket_table = lttng_ust_lfht_alloc_bucket_table,
- .free_bucket_table = lttng_ust_lfht_free_bucket_table,
- .bucket_at = bucket_at,
-};
projects / lttng-ust.git / blobdiff