> > proposes extensions to [2], which will make swap reservation and
> > locked memory resource controls easy to configure on a zone via
> > zonecfg(1m).
>
> I'm not sure if this is exactly the right place to bring this up,
> but
> there needs to be some clarity to the user community about the
> definition of swap. Due to the fact that it is not essential to the
> discussion of the particular ARC case, PSARC-EXT has not been Cc'd.
>
> The key places that the term "swap" is exposed to users currently is
> vmstat(1M) and swap(1M). A search through the relevant sysadmin
> guides and grepping through /usr/share/man turns up this somewhat
> unapproachable definition in "System Aministration Guide: Devices
> and
> File Systems":
>
>The Solaris OS uses the concept of virtual swap space, a
>layer between anonymous memory pages and the physical
>storage (or disk-backed swap space) that actually back these
>pages. A system's virtual swap space is equal to the sum of
>all its physical (disk-backed) swap space plus a portion of
>the currently available physical memory.
>
> The man pages for vmstat and swap are not especially clear as to
> whether they are talking about swap space (blocks in a swap device)
> or
> "virtual swap space", a term that I have only seen in the Devices
> and
> File Systems book. That, combined with the fact that "devices and
> file systems" is not the first place a person would expect to find
> this information, frequently leads to a misunderstanding of what the
> definition of "swap" is.
>
> As prstat is changed and resource controls are added to limit swap
> reservations, it would be extremely helpful to ensure that swap is
> clearly defined. This likely includes a definition in a man page
> (time for swapfs(7s)?) and references to that definition in relevant
> man pages.
I agree that "swap" is generally poorly defined and misunderstood.
Hopefully, a future "memory sets + swap sets" feature make the
components of swap easier to understand and manage.
It seems reasonable to file bugs to get the appropriate manpages
updated with better definitions:
vmstat(1m)
swap(1m)
prstat(1)
swap(1m) sort of defines this in the "-s" case, but it could be better.
vmstat(1m) is lacking, and of course prstat(1) will need to be updated
anyhow for this change.
We will also update the zones/rm/container admin guide with a swap
overview when we document zone.max-swap.
-Steve
>
> Mike
>
> --
> Mike Gerdts
> http://mgerdts.blogspot.com/
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