源码分析: Memzone¶

概述¶

memzone的示意图如下：

初始化¶

在EAL初始化过程中，先调用rte_eal_memory_init()进行了大页内存初始化，紧接着调用rte_eal_memzone_init()进行了memzone的初始化。

rte_eal_memzone_init (librte_eal/common/eal_common_memzone.c)

memseg = rte_eal_get_physmem_layout();

rte_rwlock_write_lock(&mcfg->mlock);
mcfg->memzone_cnt = 0;
memset(mcfg->memzone, 0, sizeof(mcfg->memzone));
rte_rwlock_write_unlock(&mcfg->mlock);

return rte_eal_malloc_heap_init();

在rte_eal_malloc_heap_init中，把各个memory segment挂到malloc heap链表中，以供之后使用。详见 malloc heap初始化

内存分配¶

核心函数是memzone_reserve_aligned_thread_unsafe(librte_eal/common/eal_common_memzone.c)。

内存分配通过malloc_heap_alloc完成，见内存分配。之后构造memzone结构体并返回。

void *mz_addr = malloc_heap_alloc(&mcfg->malloc_heaps[socket], NULL,
            requested_len, flags, align, bound);
const struct malloc_elem *elem = malloc_elem_from_data(mz_addr);
struct rte_memzone *mz = get_next_free_memzone();
mcfg->memzone_cnt++;
snprintf(mz->name, sizeof(mz->name), "%s", name);
mz->phys_addr = rte_malloc_virt2phy(mz_addr);
mz->addr = mz_addr;
mz->len = (requested_len == 0 ? elem->size : requested_len);
mz->hugepage_sz = elem->ms->hugepage_sz;
mz->socket_id = elem->ms->socket_id;
mz->flags = 0;
mz->memseg_id = elem->ms - rte_eal_get_configuration()->mem_config->memseg;

return mz;

内存释放¶

rte_memzone_free(librte_eal/common/eal_common_memzone.c).

先求得memzone对应的idx，然后把该memzone结构体清0，最后释放堆内存。

idx = ((uintptr_t)mz - (uintptr_t)mcfg->memzone);
idx = idx / sizeof(struct rte_memzone);
addr = mcfg->memzone[idx].addr;

memset(&mcfg->memzone[idx], 0, sizeof(mcfg->memzone[idx]));
mcfg->memzone_cnt--;
rte_free(addr);

参考¶

memzone API