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Feature #9054

open

a swap.7 man page would be useful

Added by Robert Mustacchi over 4 years ago. Updated 4 months ago.

Status:
New
Priority:
Normal
Assignee:
Category:
manpage - manual pages
Start date:
2018-02-06
Due date:
% Done:

100%

Estimated time:
Difficulty:
Medium
Tags:
Gerrit CR:

Description

There is a lot of confusion around "swap" for illumos. A man page would provide a single point for users to get the info they need.

---
A user-facing version of this text from the paper would be a good start:

    A second commonly mapped VM object is known as anonymous memory. This term is used because,
    unlike file mappings, the names of the backing objects are unknown to the client. Anonymous memory
    mappings are backed by swap space; each physical page in the mapping is randomly assigned a name from
    the system’s pool of available swap space at the time the page first comes into existence. The system uses
    anonymous memory for several purposes: for private copies of data created during copy-on-write faults,
    for process data and stack segments, and as a storage resource for the tmpfs file system [Snyder1990].

(from "Virtual Swap Space in SunOS").

As a user, the stuff I'm interested in are:

  • what exactly is the resource (i.e., memory not backed by the filesystem)
  • when is it allocated (which I think are MAP_ANON and/or MAP_PRIVATE mappings, including the heap and some of the stack)
  • how can I observe how much a process or zone is using
  • how can I observe a zone's cap
Actions #1

Updated by Ryan Zezeski 4 months ago

I was recently going to refer someone to this man page when I realized it's still only in illumos-joyent. Just thought I'd add a note here so that others know we can pull in Jerry's work. If I get some free cycles soon I'll do it, I just can't at this very moment so I'm writing this comment.

https://github.com/joyent/illumos-joyent/commit/b5921b68e3c3270372dc07d568b4024543b4f957

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