Question

我试图理解＆＃34; Referenced＆＃34;在一个进程的smaps文件中。根据内核文档：

＆＃34;引用的＆＃34;表示当前标记为引用的内存量或。访问＆＃34;

我理解＆＃34;访问＆＃34;的含义，但它的含义是什么＆＃34;引用＆＃34;？如果它是所有被访问的内存，那么我希望它是＆＃34; RSS＆＃34; +＆＃34;交换＆＃34;，但在下面的示例中，它不是那样的。

示例：

7f13e7577000-7f13e75c1000 rw-p 00000000 00:00 0                          [heap]
Size:                296 kB
Rss:                 156 kB
Pss:                 156 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         4 kB
Private_Dirty:       152 kB
Referenced:          128 kB
Anonymous:           156 kB
AnonHugePages:         0 kB
Swap:                 56 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB
Locked:                0 kB

Answer 1

从定义内存页面的referenced标志位的Linux kernel source code

PG_referenced，PG_reclaim用于回收匿名，文件支持的pagecache的页面。

在page_check_references()中使用referenced标志位，其中进一步记录为，

/*
* All mapped pages start out with page table
* references from the instantiating fault, so we need
* to look twice if a mapped file page is used more
* than once.
*
* Mark it and spare it for another trip around the
* inactive list. Another page table reference will
* lead to its activation.
*
* Note: the mark is set for activated pages as well
* so that recently deactivated but used pages are
* quickly recovered.
*/

此外，mark_page_accessed()是从Linux内核中的各个位置调用的函数，它通过其生命周期的初始部分对页面的referenced标志位进行更新：
（即从新分配页面开始）

* Mark a page as having seen activity.
*
* inactive,unreferenced  ->  inactive,referenced
* inactive,referenced    ->  active,unreferenced
* active,unreferenced    ->  active,referenced
*
* When a newly allocated page is not yet visible, so safe for non-atomic ops,
* __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
*/

即。 referenced =不会很快回收的活动页面缓存。

＆＃34;引用＆＃34;的含义在过程中粉碎

1 个答案: