How to analyze WIRED Pages?

[watermelonyu]

我們有一Alpha Server，其Memory為6GB，但由vmstat關察到wired pages 佔用空間近1.29 GB，vmstat -P如下:





WIRED Pages Break Down:



vm wired pages = 11399

ubc wired pages = 56018

meta data pages = 7861

malloc pages = 86267

contig pages = 392

user ptepages = 7068

kernel ptepages = 223

free ptepages = 9

==================

Total = 169237





Q1. wired pages 為何?

Q2. 該如何分析造成wired pages使用memory量多的原因?

[watermelonyu]

Hi Henry,



> Q1. wired pages 為何?

Total number of pages that are currently in use and cannot be used for paging.

==> This is a non-page memory that released until one program is terminated normally!



> Q2. 該如何分析造成wired pages使用memory量多的原因?

Wired memory is not directly attributable to a user process unless you examine it on a per-page basis.

The best we have is vmstat -M, which breaks wired memory down by size and by usage.



I mean it needs to collect the vmstat -M output from before and after one problem process running.



From the attached information,

WIRED Pages Break Down:



vm wired pages = 11399

ubc wired pages = 56018

meta data pages = 7861

malloc pages = 86267

contig pages = 392

user ptepages = 7068

kernel ptepages = 223

free ptepages = 9

==================

Total = 169237



You could run the "vmstat -M" for comparision both results on "vm wired pages" and "meta data pages". The other wired pages will refer to the RSS of ps comamnd from "ps -eo pid,rssize,vsize,command".



But the RSS (real memory usage) is just for refercne, in fact, because wired memory might be shared

pages, there may be more than one "process" responsible for having wired it.



Best regards,

Richard.