swap space - 代码结构

内核版本：3.6.6/3.2.9 （Hopefully, the swapper part has not changed a lot between the two versions.）

相关代码

mm/

swap.c

swapfile.c

swap_state.c

vmscan.c

代码行数

[root@localhost mm]# wc -l swap*
863 swap.c
2467 swapfile.c
401 swap_state.c
3491 vmscan.c

1. swap.c

/*
 * Perform any setup for the swap system
 */
void __init swap_setup(void)
{
    unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);

#ifdef CONFIG_SWAP
    bdi_init(swapper_space.backing_dev_info);
#endif

    /* Use a smaller cluster for small-memory machines */
    if (megs < 16)	【如果memory小于16M，page_cluster设置为2】
        page_cluster = 2;
    else
        page_cluster = 3;
    /*
     * Right now other parts of the system means that we
     * _really_ don't want to cluster much more
     */
}

2. swapfile.c

3. swap_state.c

struct address_space swapper_space = {
    .page_tree    = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
    .tree_lock    = __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock),
    .a_ops        = &swap_aops,
    .i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
    .backing_dev_info = &swap_backing_dev_info,
};

static const struct address_space_operations swap_aops = {
    .writepage    = swap_writepage,
    .set_page_dirty    = __set_page_dirty_nobuffers,
    .migratepage    = migrate_page,
};

struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
            struct vm_area_struct *vma, unsigned long addr)