我正在为Munin创建一个插件,以监视命名进程的统计信息。信息来源之一是/proc/[pid]/io。但是我很难找出rchar/ wchar和read_bytes/ 之间的区别written_bytes。
/proc/[pid]/io
rchar
wchar
read_bytes
written_bytes
它们不一样,因为它们提供不同的值。它们代表什么?
尽管proc联机帮助页令人遗憾地落后(大多数与cookie- cutter用户空间开发无关的联机帮助页/文档也是如此),但幸运的是,这些资料已在Linux内核源代码下的完全记录了下来Documentation/filesystems/proc.txt。以下是相关的位:
Documentation/filesystems/proc.txt
rchar ----- I/O counter: chars read The number of bytes which this task has caused to be read from storage. This is simply the sum of bytes which this process passed to read() and pread(). It includes things like tty IO and it is unaffected by whether or not actual physical disk IO was required (the read might have been satisfied from pagecache) wchar ----- I/O counter: chars written The number of bytes which this task has caused, or shall cause to be written to disk. Similar caveats apply here as with rchar. read_bytes ---------- I/O counter: bytes read Attempt to count the number of bytes which this process really did cause to be fetched from the storage layer. Done at the submit_bio() level, so it is accurate for block-backed filesystems. <please add status regarding NFS and CIFS at a later time> write_bytes ----------- I/O counter: bytes written Attempt to count the number of bytes which this process caused to be sent to the storage layer. This is done at page-dirtying time.